diff --git a/README.md b/README.md
index e7f43f27..d66527d5 100644
--- a/README.md
+++ b/README.md
@@ -27,22 +27,22 @@ Here is a small example of possible operations:
 
 ```cpp
 // simple numeric operations
-static_assert(10q_km / 2 == 5q_km);
+static_assert(10_q_km / 2 == 5_q_km);
 
 // unit conversions
-static_assert(1q_h == 3600q_s);
-static_assert(1q_km + 1q_m == 1001q_m);
+static_assert(1_q_h == 3600_q_s);
+static_assert(1_q_km + 1_q_m == 1001_q_m);
 
 // dimension conversions
-static_assert(1q_km / 1q_s == 1000q_m_per_s);
-static_assert(2q_km_per_h * 2q_h == 4q_km);
-static_assert(2q_km / 2q_km_per_h == 1q_h);
+static_assert(1_q_km / 1_q_s == 1000_q_m_per_s);
+static_assert(2_q_km_per_h * 2_q_h == 4_q_km);
+static_assert(2_q_km / 2_q_km_per_h == 1_q_h);
 
-static_assert(2q_m * 3q_m == 6q_m2);
+static_assert(2_q_m * 3_q_m == 6_q_m2);
 
-static_assert(10q_km / 5q_km == 2);
+static_assert(10_q_km / 5_q_km == 2);
 
-static_assert(1000 / 1q_s == 1q_kHz);
+static_assert(1000 / 1_q_s == 1_q_kHz);
 ```
 
 _Try it on the [Compiler Explorer](https://godbolt.org/z/XPmjPz)._
@@ -68,7 +68,7 @@ constexpr Speed auto avg_speed(Length auto d, Time auto t)
 int main()
 {
   using namespace units::physical::si::literals;
-  Speed auto v1 = avg_speed(220q_km, 2q_h);
+  Speed auto v1 = avg_speed(220_q_km, 2_q_h);
   Speed auto v2 = avg_speed(si::length<international::mile>(140), si::time<si::hour>(2));
   Speed auto v3 = quantity_cast<si::metre_per_second>(v2);
   Speed auto v4 = quantity_cast<int>(v3);
diff --git a/conanfile.py b/conanfile.py
index 76b05e1c..c8c578b8 100644
--- a/conanfile.py
+++ b/conanfile.py
@@ -115,11 +115,9 @@ class UnitsConan(ConanFile):
         version = Version(self.settings.compiler.version)
         if compiler == "gcc":
             self.cpp_info.cxxflags = [
-                "-Wno-literal-suffix",
-                "-Wno-non-template-friend",
+                "-Wno-non-template-friend"
             ]
         elif compiler == "Visual Studio":
             self.cpp_info.cxxflags = [
-                "/utf-8",
-                "/wd4455"
+                "/utf-8"
             ]
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index f6f02a52..ccc83c47 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -19,6 +19,7 @@
   - Added support for `exp()` mathematical support
   - Dimensionless quantities redesigned to be of `quantity` type
   - `Scalar` concept renamed to `ScalableNumber`
+  - `q_*` UDL renamed to `_q_*`
 
 - **0.5.0 May 17, 2020**
   - Major refactoring and rewrite of the library
diff --git a/docs/faq.rst b/docs/faq.rst
index 848e09fd..d17f8da8 100644
--- a/docs/faq.rst
+++ b/docs/faq.rst
@@ -36,7 +36,7 @@ Why a dimensionless quantity is not just an fundamental arithmetic type?
 In the initial design of this library the resulting type of the division of
 two quantities was their common representation type::
 
-    static_assert(std::is_same_v<decltype(10q_km / 5q_km), std::int64_t>);
+    static_assert(std::is_same_v<decltype(10_q_km / 5_q_km), std::int64_t>);
 
 The reasoning behind it was to not provide a false impression of a strong `quantity` type
 for something that looks and feels like a regular number. Also all of the mathematic
@@ -67,8 +67,13 @@ Well, this is how [ISO-80000]_ defines it (British English spelling by default).
 User Defined Literals (UDLs)
 ----------------------------
 
-Why all UDLs are prefixed with ``q_`` instead of just using unit symbol?
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Why all UDLs are prefixed with ``_q_`` instead of just using unit symbol?
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+..note ..
+
+    Every ``_q_*`` UDL will be replaced by the ``q_*`` literal when/if **mp-units**
+    will become a part of the C++ Standard Library.
 
 Usage of only unit symbols in UDLs would be a preferred approach (less to type,
 easier to understand and maintain). However, while increasing the coverage for
@@ -77,26 +82,10 @@ built-in types or numeric extensions. A few of those are: ``F`` (farad),
 ``J`` (joule), ``W`` (watt), ``K`` (kelvin), ``d`` (day),
 ``l`` or ``L`` (litre), ``erg``, ``ergps``. For a while for those we used ``_``
 prefix to make the library work at all, but at some point we had to unify the
-naming and we came up with ``q_`` prefix which results in a creation of
+naming and we came up with ``_q_`` prefix which results in a creation of
 quantity of a provided unit.
 
 
-Why do we use UDLs reserved for the C++ standard (no ``_`` prefix)?
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-This library is meant to become a part of the C++ Standard Library at some point
-in the future. We decided to work with the target interface to get implementation
-and user experience. Only thanks to this we were able to detect multiple collisions
-with literals already existing in the language in our initial approach
-(`Why all UDLs are prefixed with q_ instead of just using unit symbol?
-<#why-unicode-quantity-symbols-are-used-by-default-instead-of-ascii-only-characters>`_).
-This approach has some side effects though. We had to disable some compiler warnings
-to make it work:
-
-- ``/wd4455`` on MSVC,
-- ``-Wno-literal-suffix`` on other compilers.
-
-
 Text formatting
 ---------------
 
diff --git a/docs/framework/conversions_and_casting.rst b/docs/framework/conversions_and_casting.rst
index 5e0eaeca..5ea37905 100644
--- a/docs/framework/conversions_and_casting.rst
+++ b/docs/framework/conversions_and_casting.rst
@@ -21,9 +21,9 @@ No Conversions
 No conversions (either implicit or explicit) are available across quantities of
 different dimensions::
 
-    si::length<si::metre> d1 = 1q_s;            // Compile-time error
-    si::length<si::metre> d2(1q_s);             // Compile-time error
-    auto d3 = quantity_cast<si::metre>(1q_s);   // Compile-time error
+    si::length<si::metre> d1 = 1_q_s;            // Compile-time error
+    si::length<si::metre> d2(1_q_s);             // Compile-time error
+    auto d3 = quantity_cast<si::metre>(1_q_s);   // Compile-time error
 
 
 Implicit
@@ -33,23 +33,23 @@ Implicit conversions are allowed only across quantities of the same dimension:
 
 - for integral types with ratios that guarantee no precision loss::
 
-    si::length<si::metre, int>        d1 = 1q_km + 1q_m;  // OK
-    si::length<si::millimetre, int>   d2 = 1q_km + 1q_m;  // OK
-    si::length<si::kilometre, int>    d3 = 1q_km + 1q_m;  // Compile-time error
-    si::length<si::kilometre, int>    d4(1q_km + 1q_m);   // Compile-time error
-    si::length<si::metre, int>        d5 = 1q_m + 1q_ft;  // Compile-time error
-    si::length<si::metre, int>        d6(1q_m + 1q_ft);   // Compile-time error
+    si::length<si::metre, int>        d1 = 1_q_km + 1_q_m;  // OK
+    si::length<si::millimetre, int>   d2 = 1_q_km + 1_q_m;  // OK
+    si::length<si::kilometre, int>    d3 = 1_q_km + 1_q_m;  // Compile-time error
+    si::length<si::kilometre, int>    d4(1_q_km + 1_q_m);   // Compile-time error
+    si::length<si::metre, int>        d5 = 1_q_m + 1_q_ft;  // Compile-time error
+    si::length<si::metre, int>        d6(1_q_m + 1_q_ft);   // Compile-time error
 
 - from an integral to a floating-point representation even in case of a truncating
   ratio::
 
-    si::length<si::kilometre, double> d7 = 1q_km + 1q_m;  // OK
-    si::length<si::metre, double>     d8 = 1q_m + 1q_ft;  // OK
+    si::length<si::kilometre, double> d7 = 1_q_km + 1_q_m;  // OK
+    si::length<si::metre, double>     d8 = 1_q_m + 1_q_ft;  // OK
 
 - when both sides use a floating-point representation::
 
-    si::length<si::metre, int>        d9 = 1.23q_m;       // Compile-time error
-    si::length<si::metre, double>    d10 = 1.23q_m;       // OK
+    si::length<si::metre, int>        d9 = 1.23_q_m;        // Compile-time error
+    si::length<si::metre, double>    d10 = 1.23_q_m;        // OK
 
 
 Explicit
@@ -92,7 +92,7 @@ once and leave the rest intact:
 `quantity_point_cast` takes anything that works for `quantity_point`
 or a specific target `quantity_point`::
 
-    std::cout << "Point: " << quantity_point_cast<decltype(quantity_point{0q_m})>(d) << '\n';
+    std::cout << "Point: " << quantity_point_cast<decltype(quantity_point{0_q_m})>(d) << '\n';
 
 .. seealso::
 
@@ -108,8 +108,8 @@ As noted in the :ref:`Dimensionless Quantities` chapter, :term:`quantity of dime
 is somehow special but still obey most of the rules defined for quantities. However, as they
 represent numbers it would be highly uncomfortable to every time type::
 
-    const auto d1 = 10q_km;
-    const auto d2 = 3q_km;
+    const auto d1 = 10_q_km;
+    const auto d2 = 3_q_km;
     if(d1 / d2 > dimensionless<one, 2>) {
       // ...
     }
@@ -123,8 +123,8 @@ This is why it was decided to allow the ``dimensionless<one>`` quantity of any
 representation type to be implicitly constructible from this representation type.
 With that the above examples can be rewritten as follows::
 
-    const auto d1 = 10q_km;
-    const auto d2 = 3q_km;
+    const auto d1 = 10_q_km;
+    const auto d2 = 3_q_km;
     if(d1 / d2 > 2) {
       // ...
     }
@@ -142,8 +142,8 @@ could be ambiguous. For example::
       return d1 / d2 + 1;
     }
 
-As long as we can reason about what such code means for ``foo(10q_km, 2q_km)`` it is not that obvious 
-at all in the case of ``foo(10q_cm, 2q_ft)``. To make such code to compile for every case we have to
+As long as we can reason about what such code means for ``foo(10_q_km, 2_q_km)`` it is not that obvious 
+at all in the case of ``foo(10_q_cm, 2_q_ft)``. To make such code to compile for every case we have to
 either change the type of the resulting unit to the one having ``ratio(1)`` (:term:`coherent derived unit`)::
 
     Dimensionless auto foo(Length auto d1, Length auto d2)
@@ -162,15 +162,15 @@ There is one more important point to note here. As the the dimensionless quantit
 a number, it is never implicitly converted back to the representation type. This means that the following
 code will not compile::
 
-    auto v = std::exp(10q_m / 5q_m);
+    auto v = std::exp(10_q_m / 5_q_m);
 
 To make it compile fine we have to either explicitly get the value stored in the quantity::
 
-    auto v = std::exp(quantity_cast<one>(10q_m / 5q_m).count());
+    auto v = std::exp(quantity_cast<one>(10_q_m / 5_q_m).count());
 
 or use a mathematical wrapper function from `units` namespace::
 
-    auto v = units::exp(10q_m / 5q_m);
+    auto v = units::exp(10_q_m / 5_q_m);
 
 .. important::
 
diff --git a/docs/framework/dimensions.rst b/docs/framework/dimensions.rst
index 6fae1125..34769eeb 100644
--- a/docs/framework/dimensions.rst
+++ b/docs/framework/dimensions.rst
@@ -17,8 +17,8 @@ each other and the result will always be a quantity of the same dimension:
 .. code-block::
     :emphasize-lines: 3-4
 
-    Length auto dist1 = 2q_m;
-    Length auto dist2 = 1q_m;
+    Length auto dist1 = 2_q_m;
+    Length auto dist2 = 1_q_m;
     Length auto res1 = dist1 + dist2;
     Length auto res2 = dist1 - dist2;
 
@@ -29,7 +29,7 @@ not change:
 .. code-block::
     :emphasize-lines: 2-4
 
-    Length auto dist = 2q_m;
+    Length auto dist = 2_q_m;
     Length auto res1 = dist * 2;   // 4 m
     Length auto res2 = 3 * res1;   // 12 m
     Length auto res3 = res2 / 2;   // 6 m
@@ -41,9 +41,9 @@ probably will always end up in a quantity of a yet another dimension:
 .. code-block::
     :emphasize-lines: 4-6
 
-    Length auto dist1 = 2q_m;
-    Length auto dist2 = 3q_m;
-    Time auto dur1 = 2q_s;
+    Length auto dist1 = 2_q_m;
+    Length auto dist2 = 3_q_m;
+    Time auto dur1 = 2_q_s;
     Area auto res1 = dist1 * dist2;     // 6 m²
     Speed auto res2 = dist1 / dur1;     // 1 m/s
     Frequency auto res3 = 10 / dur1;    // 5 Hz
@@ -55,9 +55,9 @@ dimension, than we will end up with just a scalable number type:
 .. code-block::
     :emphasize-lines: 4-5
 
-    Time auto dur1 = 10q_s;
-    Time auto dur2 = 2q_s;
-    Frequency auto fr1 = 5q_Hz;
+    Time auto dur1 = 10_q_s;
+    Time auto dur2 = 2_q_s;
+    Frequency auto fr1 = 5_q_Hz;
     ScalableNumber auto v1 = dur1 / dur2;    // 5
     ScalableNumber auto v2 = dur1 * fr1;     // 50
 
@@ -69,8 +69,8 @@ The result will always be a quantity point of the same dimension:
 .. code-block::
     :emphasize-lines: 3-5
 
-    Length auto dist1 = 2q_m;
-    Length auto dist2 = 1q_m;
+    Length auto dist1 = 2_q_m;
+    Length auto dist2 = 1_q_m;
     QuantityPoint auto res1 = quantity_point{dist1} + dist2;
     QuantityPoint auto res2 = dist1 + quantity_point{dist2};
     QuantityPoint auto res3 = quantity_point{dist1} - dist2;
@@ -82,8 +82,8 @@ The result will always be a quantity point of the same dimension:
     .. code-block::
         :emphasize-lines: 3
         
-        Length auto dist1 = 2q_m;
-        Length auto dist2 = 1q_m;
+        Length auto dist1 = 2_q_m;
+        Length auto dist2 = 1_q_m;
         auto res1 = dist1 - quantity_point{dist2};  // ERROR
 
 We can also subtract two quantity points.
@@ -92,8 +92,8 @@ The result is a relative quantity of the same dimension:
 .. code-block::
     :emphasize-lines: 3
 
-    Length auto dist1 = 2q_m;
-    Length auto dist2 = 1q_m;
+    Length auto dist1 = 2_q_m;
+    Length auto dist2 = 1_q_m;
     Length auto res1 = quantity_point{dist1} - quantity_point{dist2};
 
 That's it! You can't multiply nor divide quantity points with anything else.
diff --git a/docs/framework/quantities.rst b/docs/framework/quantities.rst
index ebb1b167..93c1907f 100644
--- a/docs/framework/quantities.rst
+++ b/docs/framework/quantities.rst
@@ -48,15 +48,15 @@ values the library provides :abbr:`UDL (User Defined Literal)` s for each
 be as simple as::
 
     using namespace units::physical::si::literals;
-    constexpr auto d1 = 123q_km;    // si::length<si::kilometre, std::int64_t>
-    constexpr auto d2 = 123.q_km;   // si::length<si::kilometre, long double>
+    constexpr auto d1 = 123_q_km;    // si::length<si::kilometre, std::int64_t>
+    constexpr auto d2 = 123._q_km;   // si::length<si::kilometre, long double>
 
-``123q_km`` should be read as a quantity of length in kilometers. Initially the
-library did not use the ``q_`` prefix for UDLs but it turned out that there are
+``123_q_km`` should be read as a quantity of length in kilometers. Initially the
+library did not use the ``_q_`` prefix for UDLs but it turned out that there are
 a few unit symbols that collide with literals already existing in C and C++
 language (i.e. ``F`` (farad), ``J`` (joule), ``W`` (watt), ``K`` (kelvin),
 ``d`` (day), ``l`` or ``L`` (litre), ``erg``, ``ergps``). This is why the
-``q_`` prefix was consistently applied to all the UDLs.
+``_q_`` prefix was consistently applied to all the UDLs.
 
 
 Dimension-specific Concepts
@@ -67,7 +67,7 @@ requires quantity of a concrete dimension than dimension-specific concepts can
 be used::
 
     using namespace units::physical::si::literals;
-    constexpr Length auto d = 123q_km;  // si::length<si::kilometre, std::int64_t>
+    constexpr Length auto d = 123_q_km;  // si::length<si::kilometre, std::int64_t>
 
 .. note::
 
@@ -83,8 +83,8 @@ quantities. The usage of such a function can look as follows::
 
     using namespace units::physical::si::literals;
     using namespace units::physical::international::literals;
-    constexpr Speed auto v1 = avg_speed(220q_km, 2q_h);
-    constexpr Speed auto v2 = avg_speed(140q_mi, 2q_h);
+    constexpr Speed auto v1 = avg_speed(220_q_km, 2_q_h);
+    constexpr Speed auto v2 = avg_speed(140_q_mi, 2_q_h);
 
 In this and all other physical units libraries such a function can be
 implemented as::
@@ -142,7 +142,7 @@ but often we would like to know a specific type too. We have two options here:
 
 - query the actual dimension, unit, and representation types::
 
-    constexpr Speed auto v = avg_speed(220q_km, 2q_h);
+    constexpr Speed auto v = avg_speed(220_q_km, 2_q_h);
     using quantity_type = decltype(v);
     using dimension_type = quantity_type::dimension;
     using unit_type = quantity_type::unit;
@@ -150,7 +150,7 @@ but often we would like to know a specific type too. We have two options here:
 
 - convert or cast to a desired quantity type::
 
-    constexpr Speed auto v1 = avg_speed(220.q_km, 2q_h);
+    constexpr Speed auto v1 = avg_speed(220._q_km, 2_q_h);
     constexpr si::speed<si::metre_per_second> v2 = v1;
     constexpr Speed auto v3 = quantity_cast<si::speed<si::metre_per_second>(v1);
 
@@ -166,8 +166,8 @@ Dimensionless Quantities
 Whenever we divide two quantities of the same dimension we end up with a
 :term:`dimensionless quantity` otherwise known as :term:`quantity of dimension one`::
 
-    static_assert(10q_km / 5q_km == 2);
-    static_assert(std::is_same_v<decltype(10q_km / 5q_km), quantity<dim_one, one, std::int64_t>>);
+    static_assert(10_q_km / 5_q_km == 2);
+    static_assert(std::is_same_v<decltype(10_q_km / 5_q_km), quantity<dim_one, one, std::int64_t>>);
 
 According to the official ISO definition `dim_one` is a dimension "for which all the
 exponents of the factors corresponding to the base quantities in its quantity dimension
@@ -196,7 +196,7 @@ There are two special units provided for usage with such a quantity:
 
 For example the following code::
 
-    std::cout << quantity_cast<percent>(50.q_m / 100.q_m) << '\n';
+    std::cout << quantity_cast<percent>(50._q_m / 100._q_m) << '\n';
 
 will print ``50 %`` to the console output.
 
diff --git a/docs/framework/quantity_points.rst b/docs/framework/quantity_points.rst
index 68219158..65f1878c 100644
--- a/docs/framework/quantity_points.rst
+++ b/docs/framework/quantity_points.rst
@@ -14,7 +14,7 @@ Quantity Point Construction
 To create the quantity point object from a `quantity` we just have to pass
 the value to the `quantity_point` class template explicit constructor::
 
-    quantity_point<si::dim_length, si::kilometre, double> d(123q_km);
+    quantity_point<si::dim_length, si::kilometre, double> d(123_q_km);
 
 .. note::
 
@@ -25,7 +25,7 @@ the value to the `quantity_point` class template explicit constructor::
     `copy initialization <https://en.cppreference.com/w/cpp/language/copy_initialization>`_
     **does not compile**::
 
-        quantity_point<si::dim_length, si::kilometre, double> d = 123q_km;  // ERROR
+        quantity_point<si::dim_length, si::kilometre, double> d = 123_q_km;  // ERROR
 
 
 Differences to quantity
diff --git a/docs/framework/text_output.rst b/docs/framework/text_output.rst
index 61d97798..2b7812d6 100644
--- a/docs/framework/text_output.rst
+++ b/docs/framework/text_output.rst
@@ -18,8 +18,8 @@ stream::
 
     using namespace units::physical::si::literals;
     using namespace units::physical::international::literals;
-    constexpr Speed auto v1 = avg_speed(220.q_km, 2q_h);
-    constexpr Speed auto v2 = avg_speed(140.q_mi, 2q_h);
+    constexpr Speed auto v1 = avg_speed(220._q_km, 2_q_h);
+    constexpr Speed auto v2 = avg_speed(140._q_mi, 2_q_h);
     std::cout << v1 << '\n';  // 110 km/h
     std::cout << v2 << '\n';  // 70 mi/h
 
@@ -41,9 +41,9 @@ Stream Output Formatting
 Only a basic formatting can be applied for output streams. It includes control
 over width, fill, and alignment::
 
-    os << "|" << std::setw(10) << 123q_m << "|";                       // |     123 m|
-    os << "|" << std::setw(10) << std::left << 123q_m << "|";          // |123 m     |
-    os << "|" << std::setw(10) << std::setfill('*') << 123q_m << "|";  // |*****123 m|
+    os << "|" << std::setw(10) << 123_q_m << "|";                       // |     123 m|
+    os << "|" << std::setw(10) << std::left << 123_q_m << "|";          // |123 m     |
+    os << "|" << std::setw(10) << std::setfill('*') << 123_q_m << "|";  // |*****123 m|
 
 
 fmt::format
@@ -91,9 +91,9 @@ In case it is left empty the default formatting of ``{:%Q %q}`` is applied. The
 default formatting is also applied to the output streams. This is why the following
 code lines produce the same output::
 
-    std::cout << "Distance: " << 123q_km << "\n";
-    fmt::print("Distance: {}\n", 123q_km);
-    fmt::print("Distance: {:%Q %q}\n", 123q_km);
+    std::cout << "Distance: " << 123_q_km << "\n";
+    fmt::print("Distance: {}\n", 123_q_km);
+    fmt::print("Distance: {:%Q %q}\n", 123_q_km);
 
 
 Quantity Value, Symbol, or Both?
@@ -102,9 +102,9 @@ Quantity Value, Symbol, or Both?
 The user can easily decide to either print a whole quantity (value and symbol) or
 only its parts. Also a different quantity formatting might be applied::
 
-    fmt::print("{:%Q}", 123q_km);    // 123
-    fmt::print("{:%q}", 123q_km);    // km
-    fmt::print("{:%Q%q}", 123q_km);  // 123km
+    fmt::print("{:%Q}", 123_q_km);    // 123
+    fmt::print("{:%q}", 123_q_km);    // km
+    fmt::print("{:%Q%q}", 123_q_km);  // 123km
 
 
 Controlling Width, Fill, and Alignment
@@ -114,14 +114,14 @@ To control width, fill, and alignment the C++ standard grammar tokens ``fill-and
 and ``width`` are being used and they treat a quantity value and symbol as a contiguous
 text::
 
-    fmt::print("|{:0}|", 123q_m);     // |123 m|
-    fmt::print("|{:10}|", 123q_m);    // |     123 m|
-    fmt::print("|{:<10}|", 123q_m);   // |123 m     |
-    fmt::print("|{:>10}|", 123q_m);   // |     123 m|
-    fmt::print("|{:^10}|", 123q_m);   // |  123 m   |
-    fmt::print("|{:*<10}|", 123q_m);  // |123 m*****|
-    fmt::print("|{:*>10}|", 123q_m);  // |*****123 m|
-    fmt::print("|{:*^10}|", 123q_m);  // |**123 m***|
+    fmt::print("|{:0}|", 123_q_m);     // |123 m|
+    fmt::print("|{:10}|", 123_q_m);    // |     123 m|
+    fmt::print("|{:<10}|", 123_q_m);   // |123 m     |
+    fmt::print("|{:>10}|", 123_q_m);   // |     123 m|
+    fmt::print("|{:^10}|", 123_q_m);   // |  123 m   |
+    fmt::print("|{:*<10}|", 123_q_m);  // |123 m*****|
+    fmt::print("|{:*>10}|", 123_q_m);  // |*****123 m|
+    fmt::print("|{:*^10}|", 123_q_m);  // |**123 m***|
 
 
 ASCII-only Quantity Symbols
@@ -133,12 +133,12 @@ this by default. From the engineering point of view sometimes Unicode text  migh
 not be a solution as terminals of many (especially embedded) devices are ASCII-only.
 In such a case the unit symbol can be forced to be printed using ASCII-only characters::
 
-    fmt::print("{}", 10q_R);                 // 10 Ω
-    fmt::print("{:%Q %Aq}", 10q_R);          // 10 ohm
-    fmt::print("{}", 125q_us);               // 125 µs
-    fmt::print("{:%Q %Aq}", 125q_us);        // 125 us
-    fmt::print("{}", 9.8q_m_per_s2);         // 9.8 m/s²
-    fmt::print("{:%Q %Aq}", 9.8q_m_per_s2);  // 9.8 m/s^2
+    fmt::print("{}", 10_q_R);                 // 10 Ω
+    fmt::print("{:%Q %Aq}", 10_q_R);          // 10 ohm
+    fmt::print("{}", 125_q_us);               // 125 µs
+    fmt::print("{:%Q %Aq}", 125_q_us);        // 125 us
+    fmt::print("{}", 9.8_q_m_per_s2);         // 9.8 m/s²
+    fmt::print("{:%Q %Aq}", 9.8_q_m_per_s2);  // 9.8 m/s^2
 
 
 Controlling on How the Quantity Value Is Being Printed
@@ -146,8 +146,8 @@ Controlling on How the Quantity Value Is Being Printed
 
 ``sign`` token allows us to specify on how the value's sign is being printed::
 
-    fmt::print("{0:%Q %q},{0:%+Q %q},{0:%-Q %q},{0:% Q %q}", 1q_m);   // 1 m,+1 m,1 m, 1 m
-    fmt::print("{0:%Q %q},{0:%+Q %q},{0:%-Q %q},{0:% Q %q}", -1q_m);  // -1 m,-1 m,-1 m,-1 m
+    fmt::print("{0:%Q %q},{0:%+Q %q},{0:%-Q %q},{0:% Q %q}", 1_q_m);   // 1 m,+1 m,1 m, 1 m
+    fmt::print("{0:%Q %q},{0:%+Q %q},{0:%-Q %q},{0:% Q %q}", -1_q_m);  // -1 m,-1 m,-1 m,-1 m
 
 where:
 
@@ -159,47 +159,47 @@ where:
 
 ``precision`` token is allowed only for floating-point representation types::
 
-    fmt::print("{:%.0Q %q}", 1.2345q_m);  // 1 m
-    fmt::print("{:%.1Q %q}", 1.2345q_m);  // 1.2 m
-    fmt::print("{:%.2Q %q}", 1.2345q_m);  // 1.23 m
+    fmt::print("{:%.0Q %q}", 1.2345_q_m);  // 1 m
+    fmt::print("{:%.1Q %q}", 1.2345_q_m);  // 1.2 m
+    fmt::print("{:%.2Q %q}", 1.2345_q_m);  // 1.23 m
 
 
 :token:`units-rep-type` specifies how a value of the representation type is being
 printed. For integral types::
 
-    fmt::print("{:%bQ %q}", 42q_m);    // 101010 m
-    fmt::print("{:%BQ %q}", 42q_m);    // 101010 m
-    fmt::print("{:%dQ %q}", 42q_m);    // 42 m
-    fmt::print("{:%oQ %q}", 42q_m);    // 52 m
-    fmt::print("{:%xQ %q}", 42q_m);    // 2a m
-    fmt::print("{:%XQ %q}", 42q_m);    // 2A m
+    fmt::print("{:%bQ %q}", 42_q_m);    // 101010 m
+    fmt::print("{:%BQ %q}", 42_q_m);    // 101010 m
+    fmt::print("{:%dQ %q}", 42_q_m);    // 42 m
+    fmt::print("{:%oQ %q}", 42_q_m);    // 52 m
+    fmt::print("{:%xQ %q}", 42_q_m);    // 2a m
+    fmt::print("{:%XQ %q}", 42_q_m);    // 2A m
 
 The above can be printed in an alternate version thanks to the ``#`` token::
 
-    fmt::print("{:%#bQ %q}", 42q_m);   // 0b101010 m
-    fmt::print("{:%#BQ %q}", 42q_m);   // 0B101010 m
-    fmt::print("{:%#oQ %q}", 42q_m);   // 052 m
-    fmt::print("{:%#xQ %q}", 42q_m);   // 0x2a m
-    fmt::print("{:%#XQ %q}", 42q_m);   // 0X2A m
+    fmt::print("{:%#bQ %q}", 42_q_m);   // 0b101010 m
+    fmt::print("{:%#BQ %q}", 42_q_m);   // 0B101010 m
+    fmt::print("{:%#oQ %q}", 42_q_m);   // 052 m
+    fmt::print("{:%#xQ %q}", 42_q_m);   // 0x2a m
+    fmt::print("{:%#XQ %q}", 42_q_m);   // 0X2A m
 
 For floating-point values the :token:`units-rep-type` token works as follows::
 
-    fmt::print("{:%aQ %q}",   1.2345678q_m);      // 0x9.e065152d8eae841p-3 m
-    fmt::print("{:%.3aQ %q}", 1.2345678q_m);      // 0x9.e06p-3 m
-    fmt::print("{:%AQ %q}",   1.2345678q_m);      // 0X9.E065152D8EAE841P-3 m
-    fmt::print("{:%.3AQ %q}", 1.2345678q_m);      // 0X9.E06P-3 m
-    fmt::print("{:%eQ %q}",   1.2345678q_m);      // 1.234568e+00 m
-    fmt::print("{:%.3eQ %q}", 1.2345678q_m);      // 1.235e+00 m
-    fmt::print("{:%EQ %q}",   1.2345678q_m);      // 1.234568E+00 m
-    fmt::print("{:%.3EQ %q}", 1.2345678q_m);      // 1.235E+00 m
-    fmt::print("{:%gQ %q}",   1.2345678q_m);      // 1.23457 m
-    fmt::print("{:%gQ %q}",   1.2345678e8q_m);    // 1.23457e+08 m
-    fmt::print("{:%.3gQ %q}", 1.2345678q_m);      // 1.23 m
-    fmt::print("{:%.3gQ %q}", 1.2345678e8q_m);    // 1.23e+08 m
-    fmt::print("{:%GQ %q}",   1.2345678q_m);      // 1.23457 m
-    fmt::print("{:%GQ %q}",   1.2345678e8q_m);    // 1.23457E+08 m
-    fmt::print("{:%.3GQ %q}", 1.2345678q_m);      // 1.23 m
-    fmt::print("{:%.3GQ %q}", 1.2345678e8q_m);    // 1.23E+08 m
+    fmt::print("{:%aQ %q}",   1.2345678_q_m);      // 0x9.e065152d8eae841p-3 m
+    fmt::print("{:%.3aQ %q}", 1.2345678_q_m);      // 0x9.e06p-3 m
+    fmt::print("{:%AQ %q}",   1.2345678_q_m);      // 0X9.E065152D8EAE841P-3 m
+    fmt::print("{:%.3AQ %q}", 1.2345678_q_m);      // 0X9.E06P-3 m
+    fmt::print("{:%eQ %q}",   1.2345678_q_m);      // 1.234568e+00 m
+    fmt::print("{:%.3eQ %q}", 1.2345678_q_m);      // 1.235e+00 m
+    fmt::print("{:%EQ %q}",   1.2345678_q_m);      // 1.234568E+00 m
+    fmt::print("{:%.3EQ %q}", 1.2345678_q_m);      // 1.235E+00 m
+    fmt::print("{:%gQ %q}",   1.2345678_q_m);      // 1.23457 m
+    fmt::print("{:%gQ %q}",   1.2345678e8_q_m);    // 1.23457e+08 m
+    fmt::print("{:%.3gQ %q}", 1.2345678_q_m);      // 1.23 m
+    fmt::print("{:%.3gQ %q}", 1.2345678e8_q_m);    // 1.23e+08 m
+    fmt::print("{:%GQ %q}",   1.2345678_q_m);      // 1.23457 m
+    fmt::print("{:%GQ %q}",   1.2345678e8_q_m);    // 1.23457E+08 m
+    fmt::print("{:%.3GQ %q}", 1.2345678_q_m);      // 1.23 m
+    fmt::print("{:%.3GQ %q}", 1.2345678e8_q_m);    // 1.23E+08 m
 
 
 Special Signs
@@ -208,7 +208,7 @@ Special Signs
 Beside adding any list of regular characters as a separator between the value and the
 symbol, it is possible to type a few special signs there too::
 
-    fmt::print("{:%Q_%q}", 123q_km);    // 123_km
-    fmt::print("{:%Q%t%q}", 123q_km);   // 123\tkm  <tab>
-    fmt::print("{:%Q%n%q}", 123q_km);   // 123\nkm  <new line>
-    fmt::print("{:%Q%% %q}", 123q_km);  // 123% km
+    fmt::print("{:%Q_%q}", 123_q_km);    // 123_km
+    fmt::print("{:%Q%t%q}", 123_q_km);   // 123\tkm  <tab>
+    fmt::print("{:%Q%n%q}", 123_q_km);   // 123\nkm  <new line>
+    fmt::print("{:%Q%% %q}", 123_q_km);  // 123% km
diff --git a/docs/framework/units.rst b/docs/framework/units.rst
index be36e46b..52c9479e 100644
--- a/docs/framework/units.rst
+++ b/docs/framework/units.rst
@@ -381,7 +381,7 @@ unknown/undefined unit type like in the below example::
 
     using namespace units::physical::si::literals;
 
-    Length auto l = 100q_km_per_h * 10q_s;
+    Length auto l = 100_q_km_per_h * 10_q_s;
 
 The type of ``l`` above will be
 :expr:`si::length<scaled_unit<ratio(1, 36, 1), si::metre>, long double>`. This is caused
diff --git a/docs/quick_start.rst b/docs/quick_start.rst
index b30688e4..28c3b738 100644
--- a/docs/quick_start.rst
+++ b/docs/quick_start.rst
@@ -4,22 +4,22 @@ Quick Start
 Here is a small example of possible operations::
 
     // simple numeric operations
-    static_assert(10q_km / 2 == 5q_km);
+    static_assert(10_q_km / 2 == 5_q_km);
 
     // unit conversions
-    static_assert(1q_h == 3600q_s);
-    static_assert(1q_km + 1q_m == 1001q_m);
+    static_assert(1_q_h == 3600_q_s);
+    static_assert(1_q_km + 1_q_m == 1001_q_m);
 
     // dimension conversions
-    static_assert(1q_km / 1q_s == 1000q_m_per_s);
-    static_assert(2q_km_per_h * 2q_h == 4q_km);
-    static_assert(2q_km / 2q_km_per_h == 1q_h);
+    static_assert(1_q_km / 1_q_s == 1000_q_m_per_s);
+    static_assert(2_q_km_per_h * 2_q_h == 4_q_km);
+    static_assert(2_q_km / 2_q_km_per_h == 1_q_h);
 
-    static_assert(2q_m * 3q_m == 6q_m2);
+    static_assert(2_q_m * 3_q_m == 6_q_m2);
 
-    static_assert(10q_km / 5q_km == 2);
+    static_assert(10_q_km / 5_q_km == 2);
 
-    static_assert(1000 / 1q_s == 1q_kHz);
+    static_assert(1000 / 1_q_s == 1_q_kHz);
 
 .. admonition:: Try it on Compiler Explorer
 
@@ -46,7 +46,7 @@ of basic library features::
     int main()
     {
       using namespace units::physical::si::literals;
-      Speed auto v1 = avg_speed(220q_km, 2q_h);
+      Speed auto v1 = avg_speed(220_q_km, 2_q_h);
       Speed auto v2 = avg_speed(si::length<international::mile>(140), si::time<si::hour>(2));
       Speed auto v3 = quantity_cast<si::metre_per_second>(v2);
       Speed auto v4 = quantity_cast<int>(v3);
diff --git a/docs/use_cases/custom_representation_types.rst b/docs/use_cases/custom_representation_types.rst
index f650a0f3..dce853fe 100644
--- a/docs/use_cases/custom_representation_types.rst
+++ b/docs/use_cases/custom_representation_types.rst
@@ -90,7 +90,7 @@ representation types we have to obey similar rules::
 This also applies when we want to create a quantity with a custom representation type
 from a regular quantity value::
 
-    Length auto d = 123q_m;
+    Length auto d = 123_q_m;
     si::length<si::metre, impl> d1(d);                      // OK
     si::length<si::metre, expl> d2(d);                      // Compile-time error
     si::length<si::metre, expl> d3(quantity_cast<expl>(d)); // OK
diff --git a/docs/use_cases/extensions.rst b/docs/use_cases/extensions.rst
index 2df24018..b36e11a0 100644
--- a/docs/use_cases/extensions.rst
+++ b/docs/use_cases/extensions.rst
@@ -130,7 +130,7 @@ coherent unit::
 
 With the above we can now check what is the production rate::
 
-    DeskRate auto rate = quantity_cast<desk_per_hour>(3._d / 20q_min);
+    DeskRate auto rate = quantity_cast<desk_per_hour>(3._d / 20_q_min);
     std::cout << "Desk rate: " << rate << '\n';  // prints 'Desk rate: 9 desk/h'
 
 and how much wood is being consumed over a unit of time::
diff --git a/docs/use_cases/linear_algebra.rst b/docs/use_cases/linear_algebra.rst
index 804bf8b5..0a138f02 100644
--- a/docs/use_cases/linear_algebra.rst
+++ b/docs/use_cases/linear_algebra.rst
@@ -27,28 +27,28 @@ The official :term:`quantity` definition states:
 
 So the most common use case would be to create a vector or matrix of quantities::
 
-    fs_vector<si::length<si::metre>, 3> v = { 1q_m, 2q_m, 3q_m };
-    fs_vector<si::length<si::metre>, 3> u = { 3q_m, 2q_m, 1q_m };
-    fs_vector<si::length<si::kilometre>, 3> t = { 3q_km, 2q_km, 1q_km };
+    fs_vector<si::length<si::metre>, 3> v = { 1_q_m, 2_q_m, 3_q_m };
+    fs_vector<si::length<si::metre>, 3> u = { 3_q_m, 2_q_m, 1_q_m };
+    fs_vector<si::length<si::kilometre>, 3> t = { 3_q_km, 2_q_km, 1_q_km };
 
 Having such definitions we can perform full dimensional analysis operations for the operations
 allowed by the Linear Algebra rules. For example::
 
-    std::cout << "v + u    = " << v + u << "\n";
-    std::cout << "v + t    = " << v + t << "\n";
-    std::cout << "t[m]     = " << vector<si::length<si::metre>>(t) << "\n";
-    std::cout << "v * u    = " << v * u << "\n";
-    std::cout << "2q_m * v = " << 2q_m * v << "\n";
+    std::cout << "v + u     = " << v + u << "\n";
+    std::cout << "v + t     = " << v + t << "\n";
+    std::cout << "t[m]      = " << vector<si::length<si::metre>>(t) << "\n";
+    std::cout << "v * u     = " << v * u << "\n";
+    std::cout << "2_q_m * v = " << 2_q_m * v << "\n";
 
 The above code works as expected and produces the following output:
 
 .. code-block:: text
 
-    v + u    = |       4 m       4 m       4 m |
-    v + t    = |    3001 m    2002 m    1003 m |
-    t[m]     = |    3000 m    2000 m    1000 m |
-    v * u    = 10 m²
-    2q_m * v = |     2 m²     4 m²     6 m² |
+    v + u     = |       4 m       4 m       4 m |
+    v + t     = |    3001 m    2002 m    1003 m |
+    t[m]      = |    3000 m    2000 m    1000 m |
+    v * u     = 10 m²
+    2_q_m * v = |     2 m²     4 m²     6 m² |
 
 
 Quantities of Linear Algebra Types
@@ -74,14 +74,14 @@ output:
 
 .. code-block:: text
 
-    v + u    = |         4         4         4 | m
-    v + t    = |      3001      2002      1003 | m
-    t[m]     = |      3000      2000      1000 | m
-    v * u    = 10 m²
-    2q_m * v = |         2         4         6 | m²
+    v + u     = |         4         4         4 | m
+    v + t     = |      3001      2002      1003 | m
+    t[m]      = |      3000      2000      1000 | m
+    v * u     = 10 m²
+    2_q_m * v = |         2         4         6 | m²
 
 
 .. seealso::
 
     For more examples of Linear Algebra definition and operations please refer to
-    the :ref:`linear_algebra` example.
\ No newline at end of file
+    the :ref:`linear_algebra` example.
diff --git a/docs/use_cases/unknown_dimensions.rst b/docs/use_cases/unknown_dimensions.rst
index c71ea45b..58764028 100644
--- a/docs/use_cases/unknown_dimensions.rst
+++ b/docs/use_cases/unknown_dimensions.rst
@@ -26,7 +26,7 @@ will determine its type. The same applies to the resulting unit. For example:
 
     using namespace units::physical::si;
 
-    constexpr auto result = 144q_km / 2q_h;
+    constexpr auto result = 144_q_km / 2_q_h;
     static_assert(is_same_v<decltype(result)::dimension, dim_speed>);
     static_assert(is_same_v<decltype(result)::unit, kilometre_per_hour>);
 
@@ -44,7 +44,7 @@ we forget to include a header file with the resulting dimension definition:
 
     using namespace units::physical::si;
 
-    constexpr auto result = 144q_km / 2q_h;
+    constexpr auto result = 144_q_km / 2_q_h;
     static_assert(is_same_v<decltype(result)::dimension,
                             unknown_dimension<exponent<dim_length, 1>, exponent<dim_time, -1>>>);
     static_assert(is_same_v<decltype(result)::unit,
@@ -96,10 +96,10 @@ in your program. A typical example here are temporary results of a long calculat
     {
       Speed auto s1 = avg_speed(d, t);
 
-      auto temp1 = s1 * 200q_km;  // intermediate unknown dimension
+      auto temp1 = s1 * 200_q_km;      // intermediate unknown dimension
 
-      Speed auto s2 = temp1 / 50q_km; // back to known dimensions again
-      Length auto d2 = s2 * 4q_h;
+      Speed auto s2 = temp1 / 50_q_km; // back to known dimensions again
+      Length auto d2 = s2 * 4_q_h;
 
       // ...
     }
diff --git a/example/alternative_namespaces/box_example.cpp b/example/alternative_namespaces/box_example.cpp
index d22c9bc6..bdfb4038 100644
--- a/example/alternative_namespaces/box_example.cpp
+++ b/example/alternative_namespaces/box_example.cpp
@@ -56,11 +56,11 @@ using namespace units::physical::si::literals;
 
 int main()
 {
-  auto box = Box{1000.0q_mm, 500.0q_mm, 200.0q_mm};
-  box.set_contents_density(1000.0q_kg_per_m3);
+  auto box = Box{1000.0_q_mm, 500.0_q_mm, 200.0_q_mm};
+  box.set_contents_density(1000.0_q_kg_per_m3);
 
-  auto fill_time = 200.0q_s;      // time since starting fill
-  auto measured_mass = 20.0q_kg;  // measured mass at fill_time
+  auto fill_time = 200.0_q_s;      // time since starting fill
+  auto measured_mass = 20.0_q_kg;  // measured mass at fill_time
 
   std::cout << "mpusz/units box example ( using experimental alternative syntax for defining quantities) ...\n";
   std::cout << "fill height at " << fill_time << " = " << box.fill_level(measured_mass) << " ("
diff --git a/example/alternative_namespaces/capacitor_time_curve.cpp b/example/alternative_namespaces/capacitor_time_curve.cpp
index e62a1408..87a70a3c 100644
--- a/example/alternative_namespaces/capacitor_time_curve.cpp
+++ b/example/alternative_namespaces/capacitor_time_curve.cpp
@@ -36,22 +36,22 @@ int main()
   std::cout.setf(std::ios_base::fixed, std::ios_base::floatfield);
   std::cout.precision(3);
 
-  constexpr auto C = 0.47q_uF;
-  constexpr auto V0 = 5.0q_V;
-  constexpr auto R = 4.7q_kR;
+  constexpr auto C = 0.47_q_uF;
+  constexpr auto V0 = 5.0_q_V;
+  constexpr auto R = 4.7_q_kR;
 
-  for (auto t = 0q_ms; t <= 50q_ms; ++t) {
+  for (auto t = 0_q_ms; t <= 50_q_ms; ++t) {
     const auto Vt = V0 * units::exp(-t / (R * C));
 
     std::cout << "at " << t << " voltage is ";
 
-    if (Vt >= 1q_V)
+    if (Vt >= 1_q_V)
       std::cout << Vt;
-    else if (Vt >= 1q_mV)
+    else if (Vt >= 1_q_mV)
       std::cout << voltage::mV<>{Vt};
-    else if (Vt >= 1q_uV)
+    else if (Vt >= 1_q_uV)
       std::cout << voltage::uV<>{Vt};
-    else if (Vt >= 1q_nV)
+    else if (Vt >= 1_q_nV)
       std::cout << voltage::nV<>{Vt};
     else
       std::cout << voltage::pV<>{Vt};
diff --git a/example/alternative_namespaces/clcpp_response.cpp b/example/alternative_namespaces/clcpp_response.cpp
index 6d295ed6..ab79d586 100644
--- a/example/alternative_namespaces/clcpp_response.cpp
+++ b/example/alternative_namespaces/clcpp_response.cpp
@@ -33,12 +33,12 @@ void simple_quantities()
   using distance = length::m<>;
   using q_time = q_time::s<>;
 
-  constexpr distance km = 1.0q_km;
-  constexpr distance miles = 1.0q_mi;
+  constexpr distance km = 1.0_q_km;
+  constexpr distance miles = 1.0_q_mi;
 
-  constexpr q_time sec = 1q_s;
-  constexpr q_time min = 1q_min;
-  constexpr q_time hr = 1q_h;
+  constexpr q_time sec = 1_q_s;
+  constexpr q_time min = 1_q_min;
+  constexpr q_time hr = 1_q_h;
 
   std::cout << "A physical quantities library can choose the simple\n";
   std::cout << "option to provide output using a single type for each base unit:\n\n";
@@ -51,12 +51,12 @@ void simple_quantities()
 
 void quantities_with_typed_units()
 {
-  constexpr length::km<> km = 1.0q_km;
-  constexpr length::mi<> miles = 1.0q_mi;
+  constexpr length::km<> km = 1.0_q_km;
+  constexpr length::mi<> miles = 1.0_q_mi;
 
-  constexpr q_time::s<> sec = 1q_s;
-  constexpr q_time::min<> min = 1q_min;
-  constexpr q_time::h<> hr = 1q_h;
+  constexpr q_time::s<> sec = 1_q_s;
+  constexpr q_time::min<> min = 1_q_min;
+  constexpr q_time::h<> hr = 1_q_h;
 
   std::cout << "A more flexible option is to provide separate types for each unit,\n\n";
   std::cout << km << '\n';
@@ -65,7 +65,7 @@ void quantities_with_typed_units()
   std::cout << min << '\n';
   std::cout << hr << "\n\n";
 
-  constexpr length::m<> meter = 1q_m;
+  constexpr length::m<> meter = 1_q_m;
   std::cout << "then a wide range of pre-defined units can be defined and converted,\n"
                " for consistency and repeatability across applications:\n\n";
 
@@ -97,8 +97,8 @@ void calcs_comparison()
                "when adding two values of the same very big\n"
                "or very small type:\n\n";
 
-  length::fm<float> L1A = 2.q_fm;
-  length::fm<float> L2A = 3.q_fm;
+  length::fm<float> L1A = 2._q_fm;
+  length::fm<float> L2A = 3._q_fm;
   length::fm<float> LrA = L1A + L2A;
   fmt::print("{:%.30Q %q}\n + {:%.30Q %q}\n   = {:%.30Q %q}\n\n",L1A,L2A,LrA);
 
diff --git a/example/alternative_namespaces/conversion_factor.cpp b/example/alternative_namespaces/conversion_factor.cpp
index 8e11a66e..cfd9cb31 100644
--- a/example/alternative_namespaces/conversion_factor.cpp
+++ b/example/alternative_namespaces/conversion_factor.cpp
@@ -47,7 +47,7 @@ int main()
 {
   std::cout << "conversion factor in mpusz/units...\n\n";
 
-  constexpr length::m<> lengthA = 2.0q_m;
+  constexpr length::m<> lengthA = 2.0_q_m;
   constexpr length::mm<> lengthB = lengthA;
 
   std::cout << "lengthA( " << lengthA << " ) and lengthB( " << lengthB << " )\n"
diff --git a/example/alternative_namespaces/timer.cpp b/example/alternative_namespaces/timer.cpp
index 3f173f4b..520a1f72 100644
--- a/example/alternative_namespaces/timer.cpp
+++ b/example/alternative_namespaces/timer.cpp
@@ -13,7 +13,7 @@ int main()
 {
    std::cout << "Simple timer using mpusz/units ...\n";
 
-   auto const period = 0.5q_s;
+   auto const period = 0.5_q_s;
    auto const duration = 10 * period;
 
    timer t;
diff --git a/example/avg_speed.cpp b/example/avg_speed.cpp
index ce7d3782..7021ee0d 100644
--- a/example/avg_speed.cpp
+++ b/example/avg_speed.cpp
@@ -68,7 +68,7 @@ void example()
   // SI (int)
   {
     using namespace units::physical::si::literals;
-    constexpr Length auto distance = 220q_km;      // constructed from a UDL
+    constexpr Length auto distance = 220_q_km;     // constructed from a UDL
     constexpr si::time<si::hour, int> duration(2); // constructed from a value
 
     std::cout << "SI units with 'int' as representation\n";
@@ -82,7 +82,7 @@ void example()
   // SI (double)
   {
     using namespace units::physical::si::literals;
-    constexpr Length auto distance = 220.q_km;  // constructed from a UDL
+    constexpr Length auto distance = 220._q_km; // constructed from a UDL
     constexpr si::time<si::hour> duration(2);   // constructed from a value
 
     std::cout << "\nSI units with 'double' as representation\n";
@@ -98,7 +98,7 @@ void example()
   // Customary Units (int)
   {
     using namespace units::physical::international::literals;
-    constexpr Length auto distance = 140q_mi;      // constructed from a UDL
+    constexpr Length auto distance = 140_q_mi;     // constructed from a UDL
     constexpr si::time<si::hour, int> duration(2); // constructed from a value
 
     std::cout << "\nUS Customary Units with 'int' as representation\n";
@@ -114,8 +114,8 @@ void example()
   // Customary Units (double)
   {
     using namespace units::physical::international::literals;
-    constexpr Length auto distance = 140.q_mi; // constructed from a UDL
-    constexpr si::time<si::hour> duration(2);  // constructed from a value
+    constexpr Length auto distance = 140._q_mi; // constructed from a UDL
+    constexpr si::time<si::hour> duration(2);   // constructed from a value
 
     std::cout << "\nUS Customary Units with 'double' as representation\n";
 
@@ -132,7 +132,7 @@ void example()
   // CGS (int)
   {
     using namespace units::physical::cgs::literals;
-    constexpr Length auto distance = 22'000'000q_cm;  // constructed from a UDL
+    constexpr Length auto distance = 22'000'000_q_cm; // constructed from a UDL
     constexpr cgs::time<si::hour, int> duration(2);   // constructed from a value
 
     std::cout << "\nCGS units with 'int' as representation\n";
@@ -151,8 +151,8 @@ void example()
   // CGS (double)
   {
     using namespace units::physical::cgs::literals;
-    constexpr Length auto distance = 22'000'000.q_cm; // constructed from a UDL
-    constexpr cgs::time<si::hour> duration(2);        // constructed from a value
+    constexpr Length auto distance = 22'000'000._q_cm; // constructed from a UDL
+    constexpr cgs::time<si::hour> duration(2);         // constructed from a value
 
     std::cout << "\nCGS units with 'double' as representation\n";
 
diff --git a/example/box_example.cpp b/example/box_example.cpp
index 2329a287..cb2c6d38 100644
--- a/example/box_example.cpp
+++ b/example/box_example.cpp
@@ -25,7 +25,7 @@ inline constexpr auto g = si::si2019::standard_gravity<>;
 }  // namespace
 
 struct Box {
-  static constexpr auto air_density = 1.225q_kg_per_m3;
+  static constexpr auto air_density = 1.225_q_kg_per_m3;
 
   si::length<m> length;
   si::length<m> width;
@@ -65,11 +65,11 @@ struct Box {
 
 int main()
 {
-  auto box = Box(1000.0q_mm, 500.0q_mm, 200.0q_mm);
-  box.set_contents_density(1000.0q_kg_per_m3);
+  auto box = Box(1000.0_q_mm, 500.0_q_mm, 200.0_q_mm);
+  box.set_contents_density(1000.0_q_kg_per_m3);
 
-  const auto fill_time = 200.0q_s;      // time since starting fill
-  const auto measured_mass = 20.0q_kg;  // measured mass at fill_time
+  const auto fill_time = 200.0_q_s;      // time since starting fill
+  const auto measured_mass = 20.0_q_kg;  // measured mass at fill_time
 
   std::cout << "mp-units box example...\n";
   std::cout << "fill height at " << fill_time << " = " << box.fill_level(measured_mass) << " ("
diff --git a/example/capacitor_time_curve.cpp b/example/capacitor_time_curve.cpp
index 51a3e446..f2709af1 100644
--- a/example/capacitor_time_curve.cpp
+++ b/example/capacitor_time_curve.cpp
@@ -36,22 +36,22 @@ int main()
   std::cout.setf(std::ios_base::fixed, std::ios_base::floatfield);
   std::cout.precision(3);
 
-  constexpr auto C = 0.47q_uF;
-  constexpr auto V0 = 5.0q_V;
-  constexpr auto R = 4.7q_kR;
+  constexpr auto C = 0.47_q_uF;
+  constexpr auto V0 = 5.0_q_V;
+  constexpr auto R = 4.7_q_kR;
 
-  for (auto t = 0q_ms; t <= 50q_ms; ++t) {
+  for (auto t = 0_q_ms; t <= 50_q_ms; ++t) {
     const Voltage auto Vt = V0 * units::exp(-t / (R * C));
 
     std::cout << "at " << t << " voltage is ";
 
-    if (Vt >= 1q_V)
+    if (Vt >= 1_q_V)
       std::cout << Vt;
-    else if (Vt >= 1q_mV)
+    else if (Vt >= 1_q_mV)
       std::cout << quantity_cast<millivolt>(Vt);
-    else if (Vt >= 1q_uV)
+    else if (Vt >= 1_q_uV)
       std::cout << quantity_cast<microvolt>(Vt);
-    else if (Vt >= 1q_nV)
+    else if (Vt >= 1_q_nV)
       std::cout << quantity_cast<nanovolt>(Vt);
     else
       std::cout << quantity_cast<picovolt>(Vt);
diff --git a/example/clcpp_response.cpp b/example/clcpp_response.cpp
index c117ed25..c8e7f913 100644
--- a/example/clcpp_response.cpp
+++ b/example/clcpp_response.cpp
@@ -39,12 +39,12 @@ void simple_quantities()
   using distance = length<metre>;
   using duration = physical::si::time<second>;
 
-  constexpr distance km = 1.0q_km;
-  constexpr distance miles = 1.0q_mi;
+  constexpr distance km = 1.0_q_km;
+  constexpr distance miles = 1.0_q_mi;
 
-  constexpr duration sec = 1q_s;
-  constexpr duration min = 1q_min;
-  constexpr duration hr = 1q_h;
+  constexpr duration sec = 1_q_s;
+  constexpr duration min = 1_q_min;
+  constexpr duration hr = 1_q_h;
 
   std::cout << "A physical quantities library can choose the simple\n";
   std::cout << "option to provide output using a single type for each base unit:\n\n";
@@ -61,14 +61,14 @@ void quantities_with_typed_units()
   using namespace units::physical::si;
   using namespace units::physical::international;
 
-  constexpr length<kilometre> km = 1.0q_km;
-  constexpr length<mile> miles = 1.0q_mi;
+  constexpr length<kilometre> km = 1.0_q_km;
+  constexpr length<mile> miles = 1.0_q_mi;
 
   std::cout.precision(6);
 
-  constexpr si::time<second> sec = 1q_s;
-  constexpr si::time<minute> min = 1q_min;
-  constexpr si::time<hour> hr = 1q_h;
+  constexpr si::time<second> sec = 1_q_s;
+  constexpr si::time<minute> min = 1_q_min;
+  constexpr si::time<hour> hr = 1_q_h;
 
   std::cout << "A more flexible option is to provide separate types for each unit,\n\n";
   std::cout << km << '\n';
@@ -77,7 +77,7 @@ void quantities_with_typed_units()
   std::cout << min << '\n';
   std::cout << hr << "\n\n";
 
-  constexpr length<metre> meter = 1q_m;
+  constexpr length<metre> meter = 1_q_m;
   std::cout << "then a wide range of pre-defined units can be defined and converted,\n"
                " for consistency and repeatability across applications:\n\n";
 
@@ -111,8 +111,8 @@ void calcs_comparison()
                "when adding two values of the same very big\n"
                "or very small type:\n\n";
 
-  length<femtometre,float> L1A = 2.q_fm;
-  length<femtometre,float> L2A = 3.q_fm;
+  length<femtometre,float> L1A = 2._q_fm;
+  length<femtometre,float> L2A = 3._q_fm;
   length<femtometre,float> LrA = L1A + L2A;
   fmt::print("{:%.30Q %q}\n + {:%.30Q %q}\n   = {:%.30Q %q}\n\n",L1A,L2A,LrA);
 
diff --git a/example/conversion_factor.cpp b/example/conversion_factor.cpp
index 3f9ed02d..fd73b03a 100644
--- a/example/conversion_factor.cpp
+++ b/example/conversion_factor.cpp
@@ -45,7 +45,7 @@ int main()
 
   std::cout << "conversion factor in mp-units...\n\n";
 
-  constexpr length<metre> lengthA = 2.0q_m;
+  constexpr length<metre> lengthA = 2.0_q_m;
   constexpr length<millimetre> lengthB = lengthA;
 
   std::cout << fmt::format("lengthA( {} ) and lengthB( {} )\n", lengthA, lengthB)
diff --git a/example/experimental_angle.cpp b/example/experimental_angle.cpp
index 620ebe98..c0911caf 100644
--- a/example/experimental_angle.cpp
+++ b/example/experimental_angle.cpp
@@ -31,8 +31,8 @@ using namespace units::physical::si::literals;
 
 int main()
 {
-  auto torque = 20.0q_Nm;
-  auto energy = 20.0q_J;
+  auto torque = 20.0_q_Nm;
+  auto energy = 20.0_q_J;
 
   physical::Angle auto angle = torque / energy;
 
diff --git a/example/foot_pound_second.cpp b/example/foot_pound_second.cpp
index a5ba214f..6c51fc05 100644
--- a/example/foot_pound_second.cpp
+++ b/example/foot_pound_second.cpp
@@ -67,7 +67,7 @@ auto fmt_line(const Q a)
 void print_details(std::string_view description, const Ship& ship)
 {
   using namespace units::physical::fps::literals;
-  const auto waterDensity = 62.4q_lb_per_ft3;
+  const auto waterDensity = 62.4_q_lb_per_ft3;
   std::cout << fmt::format("{}\n", description);
   std::cout << fmt::format("{:20} : {}\n", "length",    fmt_line<fps::length<fps::yard>, si::length<si::metre>>(ship.length))
             << fmt::format("{:20} : {}\n", "draft",     fmt_line<fps::length<fps::yard>, si::length<si::metre>>(ship.draft))
@@ -87,13 +87,13 @@ int main()
   using namespace units::physical::fps::literals;
   
   // KMS Bismark, using the units the Germans would use, taken from Wiki
-  auto bismark = Ship{.length{251.q_m}, .draft{9.3q_m}, .beam{36q_m}, .speed{56q_km_per_h}, .mass{50'300q_t}, .mainGuns{380q_mm}, .shellMass{800q_kg}, .shellSpeed{820.q_m_per_s}, .power{110.45q_kW}};
+  auto bismark = Ship{.length{251._q_m}, .draft{9.3_q_m}, .beam{36_q_m}, .speed{56_q_km_per_h}, .mass{50'300_q_t}, .mainGuns{380_q_mm}, .shellMass{800_q_kg}, .shellSpeed{820._q_m_per_s}, .power{110.45_q_kW}};
 
   // USS Iowa, using units from the foot-pound-second system
-  auto iowa = Ship{.length{860.q_ft}, .draft{37.q_ft + 2.q_in}, .beam{108.q_ft + 2.q_in}, .speed{33q_knot}, .mass{57'540q_lton}, .mainGuns{16q_in}, .shellMass{2700q_lb}, .shellSpeed{2690.q_ft_per_s}, .power{212'000q_hp}};
+  auto iowa = Ship{.length{860._q_ft}, .draft{37._q_ft + 2._q_in}, .beam{108._q_ft + 2._q_in}, .speed{33_q_knot}, .mass{57'540_q_lton}, .mainGuns{16_q_in}, .shellMass{2700_q_lb}, .shellSpeed{2690._q_ft_per_s}, .power{212'000_q_hp}};
 
   // HMS King George V, using units from the foot-pound-second system
-  auto kgv = Ship{.length{745.1q_ft}, .draft{33.q_ft + 7.5q_in}, .beam{103.2q_ft + 2.5q_in}, .speed{28.3q_knot}, .mass{42'245q_lton}, .mainGuns{14q_in}, .shellMass{1'590q_lb}, .shellSpeed{2483.q_ft_per_s}, .power{110'000q_hp}};
+  auto kgv = Ship{.length{745.1_q_ft}, .draft{33._q_ft + 7.5_q_in}, .beam{103.2_q_ft + 2.5_q_in}, .speed{28.3_q_knot}, .mass{42'245_q_lton}, .mainGuns{14_q_in}, .shellMass{1'590_q_lb}, .shellSpeed{2483._q_ft_per_s}, .power{110'000_q_hp}};
 
   print_details("KMS Bismark, defined in appropriate units from the SI system", bismark);
   std::cout << "\n\n";
diff --git a/example/glide_computer.cpp b/example/glide_computer.cpp
index 36d2840e..82d2085c 100644
--- a/example/glide_computer.cpp
+++ b/example/glide_computer.cpp
@@ -217,10 +217,10 @@ struct glider {
 auto get_gliders()
 {
   const std::array gliders = {
-    glider{"SZD-30 Pirat", {velocity(83q_km_per_h), rate_of_climb(-0.7389q_m_per_s)}},
-    glider{"SZD-51 Junior", {velocity(80q_km_per_h), rate_of_climb(-0.6349q_m_per_s)}},
-    glider{"SZD-48 Jantar Std 3", {velocity(110q_km_per_h), rate_of_climb(-0.77355q_m_per_s)}},
-    glider{"SZD-56 Diana", {velocity(110q_km_per_h), rate_of_climb(-0.63657q_m_per_s)}}
+    glider{"SZD-30 Pirat", {velocity(83_q_km_per_h), rate_of_climb(-0.7389_q_m_per_s)}},
+    glider{"SZD-51 Junior", {velocity(80_q_km_per_h), rate_of_climb(-0.6349_q_m_per_s)}},
+    glider{"SZD-48 Jantar Std 3", {velocity(110_q_km_per_h), rate_of_climb(-0.77355_q_m_per_s)}},
+    glider{"SZD-56 Diana", {velocity(110_q_km_per_h), rate_of_climb(-0.63657_q_m_per_s)}}
   };
   return gliders;
 }
@@ -258,9 +258,9 @@ struct weather {
 auto get_weather_conditions()
 {
   const std::array weather_conditions = {
-    std::pair("Good", weather{height(1900q_m), rate_of_climb(4.3q_m_per_s)}),
-    std::pair("Medium", weather{height(1550q_m), rate_of_climb(2.8q_m_per_s)}),
-    std::pair("Bad", weather{height(850q_m), rate_of_climb(1.8q_m_per_s)})
+    std::pair("Good", weather{height(1900_q_m), rate_of_climb(4.3_q_m_per_s)}),
+    std::pair("Medium", weather{height(1550_q_m), rate_of_climb(2.8_q_m_per_s)}),
+    std::pair("Bad", weather{height(850_q_m), rate_of_climb(1.8_q_m_per_s)})
   };
   return weather_conditions;
 }
@@ -462,7 +462,7 @@ void estimate(const glider& g, const weather& w, const task& t, const safety& s,
     // circle in a thermall to gain height
     point = circle(point, g, w, t, height_to_gain);
   }
-  while(height_to_gain > height(0q_m));
+  while(height_to_gain > height(0_q_m));
 
   // final glide
   point = final_glide(point, g, t);
@@ -482,16 +482,16 @@ void example()
   print(weather_conditions);
 
   const task t = {
-    waypoint{"EPPR", altitude(16q_ft)},
-    waypoint{"EPGI", altitude(115q_ft)},
-    distance(81.7q_km)
+    waypoint{"EPPR", altitude(16_q_ft)},
+    waypoint{"EPGI", altitude(115_q_ft)},
+    distance(81.7_q_km)
   };
   print(t);
 
-  const safety s = {height(300q_m)};
+  const safety s = {height(300_q_m)};
   print(s);
 
-  const aircraft_tow tow = {height(400q_m), rate_of_climb(1.6q_m_per_s)};
+  const aircraft_tow tow = {height(400_q_m), rate_of_climb(1.6_q_m_per_s)};
   print(tow);
 
   for(const auto& g : gliders) {
diff --git a/example/hello_units.cpp b/example/hello_units.cpp
index a49d12cb..73e31fb4 100644
--- a/example/hello_units.cpp
+++ b/example/hello_units.cpp
@@ -35,7 +35,7 @@ constexpr Speed auto avg_speed(Length auto d, Time auto t)
 int main()
 {
   using namespace units::physical::si::literals;
-  Speed auto v1 = avg_speed(220q_km, 2q_h);
+  Speed auto v1 = avg_speed(220_q_km, 2_q_h);
   Speed auto v2 = avg_speed(si::length<international::mile>(140), si::time<si::hour>(2));
   Speed auto v3 = quantity_cast<si::metre_per_second>(v2);
   Speed auto v4 = quantity_cast<int>(v3);
diff --git a/example/kalman_filter-alpha_beta_filter_example2.cpp b/example/kalman_filter-alpha_beta_filter_example2.cpp
index 72369ea8..13eeabf6 100644
--- a/example/kalman_filter-alpha_beta_filter_example2.cpp
+++ b/example/kalman_filter-alpha_beta_filter_example2.cpp
@@ -21,7 +21,7 @@ struct state_variable {
 using namespace units::physical;
 using namespace units::physical::si::literals;
 
-constexpr auto radar_transmit_interval = 5.0q_s;
+constexpr auto radar_transmit_interval = 5.0_q_s;
 constexpr double kalman_range_gain = 0.2;
 constexpr double kalman_speed_gain = 0.1;
 
@@ -52,16 +52,16 @@ int main()
   std::cout << "\n\n1d aircraft α-β filter example2 from https://www.kalmanfilter.net/alphabeta.html#ex2";
   std::cout << "\n\n";
 
-  constexpr auto measurements = std::array{0.0q_m,  // N.B measurement[0] is unknown and unused
-                                          30110.0q_m, 30265.0q_m, 30740.0q_m, 30750.0q_m, 31135.0q_m,
-                                          31015.0q_m, 31180.0q_m, 31610.0q_m, 31960.0q_m, 31865.0q_m};
+  constexpr auto measurements = std::array{0.0_q_m,  // N.B measurement[0] is unknown and unused
+                                           30110.0_q_m, 30265.0_q_m, 30740.0_q_m, 30750.0_q_m, 31135.0_q_m,
+                                           31015.0_q_m, 31180.0_q_m, 31610.0_q_m, 31960.0_q_m, 31865.0_q_m};
 
   constexpr auto num_measurements = measurements.size();
 
   std::array<state,num_measurements> track;
   // We need an initial estimate of track[0] as there is no previous state to get a prediction from
-  track[0].range.estimated_current_state = 30'000q_m;
-  track[0].speed.estimated_current_state = 40.0q_m_per_s;
+  track[0].range.estimated_current_state = 30'000_q_m;
+  track[0].speed.estimated_current_state = 40.0_q_m_per_s;
 
   for (auto n = 0U; n < num_measurements; ++n) {
     if (n > 0) {
diff --git a/example/linear_algebra.cpp b/example/linear_algebra.cpp
index e2506fac..fcf336a1 100644
--- a/example/linear_algebra.cpp
+++ b/example/linear_algebra.cpp
@@ -68,9 +68,9 @@ void vector_of_quantity_add()
 {
   std::cout << "\nvector_of_quantity_add:\n";
 
-  vector<si::length<si::metre>> v = { 1q_m, 2q_m, 3q_m };
-  vector<si::length<si::metre>> u = { 3q_m, 2q_m, 1q_m };
-  vector<si::length<si::kilometre>> t = { 3q_km, 2q_km, 1q_km };
+  vector<si::length<si::metre>> v = { 1_q_m, 2_q_m, 3_q_m };
+  vector<si::length<si::metre>> u = { 3_q_m, 2_q_m, 1_q_m };
+  vector<si::length<si::kilometre>> t = { 3_q_km, 2_q_km, 1_q_km };
 
   std::cout << "v = " << v << "\n";
   std::cout << "u = " << u << "\n";
@@ -85,28 +85,28 @@ void vector_of_quantity_multiply_same()
 {
   std::cout << "\nvector_of_quantity_multiply_same:\n";
 
-  vector<si::length<si::metre>> v = { 1q_m, 2q_m, 3q_m };
-  vector<si::length<si::metre>> u = { 3q_m, 2q_m, 1q_m };
+  vector<si::length<si::metre>> v = { 1_q_m, 2_q_m, 3_q_m };
+  vector<si::length<si::metre>> u = { 3_q_m, 2_q_m, 1_q_m };
 
   std::cout << "v = " << v << "\n";
   std::cout << "u = " << u << "\n";
 
   std::cout << "v * u    = " << v * u << "\n";
-  std::cout << "2q_m * v = " << 2.q_m * v << "\n";
+  std::cout << "2_q_m * v = " << 2._q_m * v << "\n";
 }
 
 void vector_of_quantity_multiply_different()
 {
   std::cout << "\nvector_of_quantity_multiply_different:\n";
 
-  vector<si::force<si::newton>> v = { 1q_N, 2q_N, 3q_N };
-  vector<si::length<si::metre>> u = { 3q_m, 2q_m, 1q_m };
+  vector<si::force<si::newton>> v = { 1_q_N, 2_q_N, 3_q_N };
+  vector<si::length<si::metre>> u = { 3_q_m, 2_q_m, 1_q_m };
 
   std::cout << "v = " << v << "\n";
   std::cout << "u = " << u << "\n";
 
   std::cout << "v * u    = " << v * u << "\n";
-  std::cout << "2q_N * u = " << 2.q_N * u << "\n";
+  std::cout << "2_q_N * u = " << 2._q_N * u << "\n";
   std::cout << "2 * u    = " << 2 * u << "\n";
 }
 
@@ -114,12 +114,12 @@ void vector_of_quantity_divide_by_scalar()
 {
   std::cout << "\nvector_of_quantity_divide_by_scalar:\n";
 
-  vector<si::length<si::metre>> v = { 4q_m, 8q_m, 12q_m };
+  vector<si::length<si::metre>> v = { 4_q_m, 8_q_m, 12_q_m };
 
   std::cout << "v = " << v << "\n";
 
   // TODO Uncomment when bug in the LA is fixed
-  // std::cout << "v / 2q_s = " << v / 2q_s << "\n";
+  // std::cout << "v / 2_q_s = " << v / 2_q_s << "\n";
   // std::cout << "v / 2 = " << v / 2 << "\n";
 }
 
@@ -135,9 +135,9 @@ void matrix_of_quantity_add()
 {
   std::cout << "\nmatrix_of_quantity_add:\n";
 
-  matrix<si::length<si::metre>> v = {{ 1q_m, 2q_m, 3q_m }, { 4q_m, 5q_m, 6q_m }, { 7q_m, 8q_m, 9q_m }};
-  matrix<si::length<si::metre>> u = {{ 3q_m, 2q_m, 1q_m }, { 3q_m, 2q_m, 1q_m }, { 3q_m, 2q_m, 1q_m }};
-  matrix<si::length<si::millimetre>> t = {{ 3q_mm, 2q_mm, 1q_mm }, { 3q_mm, 2q_mm, 1q_mm }, { 3q_mm, 2q_mm, 1q_mm }};
+  matrix<si::length<si::metre>> v = {{ 1_q_m, 2_q_m, 3_q_m }, { 4_q_m, 5_q_m, 6_q_m }, { 7_q_m, 8_q_m, 9_q_m }};
+  matrix<si::length<si::metre>> u = {{ 3_q_m, 2_q_m, 1_q_m }, { 3_q_m, 2_q_m, 1_q_m }, { 3_q_m, 2_q_m, 1_q_m }};
+  matrix<si::length<si::millimetre>> t = {{ 3_q_mm, 2_q_mm, 1_q_mm }, { 3_q_mm, 2_q_mm, 1_q_mm }, { 3_q_mm, 2_q_mm, 1_q_mm }};
 
   std::cout << "v =\n" << v << "\n";
   std::cout << "u =\n" << u << "\n";
@@ -154,28 +154,28 @@ void matrix_of_quantity_multiply_same()
 {
   std::cout << "\nmatrix_of_quantity_multiply_same:\n";
   
-  matrix<si::length<si::metre>> v = {{ 1q_m, 2q_m, 3q_m }, { 4q_m, 5q_m, 6q_m }, { 7q_m, 8q_m, 9q_m }};
-  vector<si::length<si::metre>> u = { 3q_m, 2q_m, 1q_m };
+  matrix<si::length<si::metre>> v = {{ 1_q_m, 2_q_m, 3_q_m }, { 4_q_m, 5_q_m, 6_q_m }, { 7_q_m, 8_q_m, 9_q_m }};
+  vector<si::length<si::metre>> u = { 3_q_m, 2_q_m, 1_q_m };
 
   std::cout << "v =\n" << v << "\n";
   std::cout << "u =\n" << u << "\n";
 
   std::cout << "v * u =\n" << v * u << "\n";
-  std::cout << "2q_m * u =\n" << 2.q_m * u << "\n";
+  std::cout << "2_q_m * u =\n" << 2._q_m * u << "\n";
 }
 
 void matrix_of_quantity_multiply_different()
 {
   std::cout << "\nmatrix_of_quantity_multiply_different:\n";
 
-  vector<si::force<si::newton>> v = { 1q_N, 2q_N, 3q_N };
-  matrix<si::length<si::metre>> u = {{ 1q_m, 2q_m, 3q_m }, { 4q_m, 5q_m, 6q_m }, { 7q_m, 8q_m, 9q_m }};
+  vector<si::force<si::newton>> v = { 1_q_N, 2_q_N, 3_q_N };
+  matrix<si::length<si::metre>> u = {{ 1_q_m, 2_q_m, 3_q_m }, { 4_q_m, 5_q_m, 6_q_m }, { 7_q_m, 8_q_m, 9_q_m }};
 
   std::cout << "v =\n" << v << "\n";
   std::cout << "u =\n" << u << "\n";
 
   std::cout << "v * u =\n" << v * u << "\n";
-  std::cout << "2q_N * u =\n" << 2.q_N * u << "\n";
+  std::cout << "2_q_N * u =\n" << 2._q_N * u << "\n";
   std::cout << "2 * u =\n" << 2 * u << "\n";
 }
 
@@ -183,12 +183,12 @@ void matrix_of_quantity_divide_by_scalar()
 {
   std::cout << "\nmatrix_of_quantity_divide_by_scalar:\n";
 
-  matrix<si::length<si::metre>> v = {{ 2q_m, 4q_m, 6q_m }, { 4q_m, 6q_m, 8q_m }, { 8q_m, 4q_m, 2q_m }};
+  matrix<si::length<si::metre>> v = {{ 2_q_m, 4_q_m, 6_q_m }, { 4_q_m, 6_q_m, 8_q_m }, { 8_q_m, 4_q_m, 2_q_m }};
 
   std::cout << "v =\n" << v << "\n";
 
   // TODO Uncomment when bug in the LA is fixed
-  // std::cout << "v / 2q_s =\n" << v / 2q_s << "\n";
+  // std::cout << "v / 2_q_s =\n" << v / 2_q_s << "\n";
   // std::cout << "v / 2 =\n" << v / 2 << "\n";
 }
 
@@ -234,7 +234,7 @@ void quantity_of_vector_multiply_same()
   std::cout << "u = " << u << "\n";
 
   std::cout << "v * u    = " << v * u << "\n";
-  std::cout << "2q_m * v = " << 2.q_m * v << "\n";
+  std::cout << "2_q_m * v = " << 2._q_m * v << "\n";
 }
 
 void quantity_of_vector_multiply_different()
@@ -248,7 +248,7 @@ void quantity_of_vector_multiply_different()
   std::cout << "u = " << u << "\n";
 
   std::cout << "v * u    = " << v * u << "\n";
-  std::cout << "2q_N * u = " << 2.q_N * u << "\n";
+  std::cout << "2_q_N * u = " << 2._q_N * u << "\n";
   std::cout << "2 * u    = " << 2 * u << "\n";
 }
 
@@ -261,7 +261,7 @@ void quantity_of_vector_divide_by_scalar()
   std::cout << "v = " << v << "\n";
 
   // TODO Uncomment when bug in the LA is fixed
-  // std::cout << "v / 2q_s = " << v / 2q_s << "\n";
+  // std::cout << "v / 2_q_s = " << v / 2_q_s << "\n";
   // std::cout << "v / 2 = " << v / 2 << "\n";
 }
 
@@ -306,7 +306,7 @@ void quantity_of_matrix_multiply_same()
   std::cout << "u =\n" << u << "\n";
 
   std::cout << "v * u =\n" << v * u << "\n";
-  std::cout << "2q_m * u =\n" << 2.q_m * u << "\n";
+  std::cout << "2_q_m * u =\n" << 2._q_m * u << "\n";
 }
 
 void quantity_of_matrix_multiply_different()
@@ -320,7 +320,7 @@ void quantity_of_matrix_multiply_different()
   std::cout << "u =\n" << u << "\n";
 
   std::cout << "v * u =\n" << v * u << "\n";
-  std::cout << "2q_N * u =\n" << 2.q_N * u << "\n";
+  std::cout << "2_q_N * u =\n" << 2._q_N * u << "\n";
   std::cout << "2 * u =\n" << 2 * u << "\n";
 }
 
@@ -333,7 +333,7 @@ void quantity_of_matrix_divide_by_scalar()
   std::cout << "v =\n" << v << "\n";
 
   // TODO Uncomment when bug in the LA is fixed
-  // std::cout << "v / 2q_s =\n" << v / 2q_s << "\n";
+  // std::cout << "v / 2_q_s =\n" << v / 2_q_s << "\n";
   // std::cout << "v / 2 =\n" << v / 2 << "\n";
 }
 
diff --git a/example/total_energy.cpp b/example/total_energy.cpp
index 3ec087ac..dc91368c 100644
--- a/example/total_energy.cpp
+++ b/example/total_energy.cpp
@@ -46,8 +46,8 @@ void si_example()
 
   std::cout << "\n*** SI units (c = " << c << ") ***\n";
 
-  const Momentum auto p = 4.q_GeV / c;
-  const Mass auto m = 3.q_GeV / pow<2>(c);
+  const Momentum auto p = 4._q_GeV / c;
+  const Mass auto m = 3._q_GeV / pow<2>(c);
   const Energy auto E = total_energy(p, m, c);
 
   std::cout << "[in GeV]\n"
diff --git a/example/unknown_dimension.cpp b/example/unknown_dimension.cpp
index cf90be90..52d70caa 100644
--- a/example/unknown_dimension.cpp
+++ b/example/unknown_dimension.cpp
@@ -36,13 +36,13 @@ void example()
   using namespace units::physical;
   using namespace units::physical::si::literals;
 
-  Length auto d1 = 123q_m;
-  Time auto t1 = 10q_s;
+  Length auto d1 = 123_q_m;
+  Time auto t1 = 10_q_s;
   Speed auto v1 = avg_speed(d1, t1);
 
-  auto temp1 = v1 * 50q_m;  // produces intermediate unknown dimension with 'unknown_coherent_unit' as its 'coherent_unit'
-  Speed auto v2 = temp1 / 100q_m; // back to known dimensions again
-  Length auto d2 = v2 * 60q_s;
+  auto temp1 = v1 * 50_q_m;  // produces intermediate unknown dimension with 'unknown_coherent_unit' as its 'coherent_unit'
+  Speed auto v2 = temp1 / 100_q_m; // back to known dimensions again
+  Length auto d2 = v2 * 60_q_s;
 
   std::cout << "d1 = " << d1 << '\n';
   std::cout << "t1 = " << t1 << '\n';
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 35ad4f77..62a6ee39 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -71,14 +71,12 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
 elseif(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
     target_compile_options(mp-units
         INTERFACE
-            -Wno-literal-suffix
             -Wno-non-template-friend
     )
 elseif(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
     target_compile_options(mp-units
         INTERFACE
             /utf-8  # Specifies both the source character set and the execution character set as UTF-8
-            /wd4455 # 'operator name': literal suffix identifiers that do not start with an underscore are reserved
     )
 endif()
 
diff --git a/src/include/units/data/bitrate.h b/src/include/units/data/bitrate.h
index 0709cde6..c1f62b54 100644
--- a/src/include/units/data/bitrate.h
+++ b/src/include/units/data/bitrate.h
@@ -47,12 +47,12 @@ using bitrate = quantity<dim_bitrate, U, Rep>;
 inline namespace literals {
 
 // bits
-constexpr auto operator"" q_b_per_s(unsigned long long l) { return bitrate<bit_per_second, std::int64_t>(l); }
-constexpr auto operator"" q_Kib_per_s(unsigned long long l) { return bitrate<kibibit_per_second, std::int64_t>(l); }
-constexpr auto operator"" q_Mib_per_s(unsigned long long l) { return bitrate<mebibit_per_second, std::int64_t>(l); }
-constexpr auto operator"" q_Gib_per_s(unsigned long long l) { return bitrate<gibibit_per_second, std::int64_t>(l); }
-constexpr auto operator"" q_Tib_per_s(unsigned long long l) { return bitrate<tebibit_per_second, std::int64_t>(l); }
-constexpr auto operator"" q_Pib_per_s(unsigned long long l) { return bitrate<pebibit_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_b_per_s(unsigned long long l) { return bitrate<bit_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_Kib_per_s(unsigned long long l) { return bitrate<kibibit_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_Mib_per_s(unsigned long long l) { return bitrate<mebibit_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_Gib_per_s(unsigned long long l) { return bitrate<gibibit_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_Tib_per_s(unsigned long long l) { return bitrate<tebibit_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_Pib_per_s(unsigned long long l) { return bitrate<pebibit_per_second, std::int64_t>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/data/information.h b/src/include/units/data/information.h
index 9995f9c8..89846916 100644
--- a/src/include/units/data/information.h
+++ b/src/include/units/data/information.h
@@ -54,20 +54,20 @@ using information = quantity<dim_information, U, Rep>;
 inline namespace literals {
 
 // bits
-constexpr auto operator"" q_b(unsigned long long l) { return information<bit, std::int64_t>(l); }
-constexpr auto operator"" q_Kib(unsigned long long l) { return information<kibibit, std::int64_t>(l); }
-constexpr auto operator"" q_Mib(unsigned long long l) { return information<mebibit, std::int64_t>(l); }
-constexpr auto operator"" q_Gib(unsigned long long l) { return information<gibibit, std::int64_t>(l); }
-constexpr auto operator"" q_Tib(unsigned long long l) { return information<tebibit, std::int64_t>(l); }
-constexpr auto operator"" q_Pib(unsigned long long l) { return information<pebibit, std::int64_t>(l); }
+constexpr auto operator"" _q_b(unsigned long long l) { return information<bit, std::int64_t>(l); }
+constexpr auto operator"" _q_Kib(unsigned long long l) { return information<kibibit, std::int64_t>(l); }
+constexpr auto operator"" _q_Mib(unsigned long long l) { return information<mebibit, std::int64_t>(l); }
+constexpr auto operator"" _q_Gib(unsigned long long l) { return information<gibibit, std::int64_t>(l); }
+constexpr auto operator"" _q_Tib(unsigned long long l) { return information<tebibit, std::int64_t>(l); }
+constexpr auto operator"" _q_Pib(unsigned long long l) { return information<pebibit, std::int64_t>(l); }
 
 // bytes
-constexpr auto operator"" q_B(unsigned long long l) { return information<byte, std::int64_t>(l); }
-constexpr auto operator"" q_KiB(unsigned long long l) { return information<kibibyte, std::int64_t>(l); }
-constexpr auto operator"" q_MiB(unsigned long long l) { return information<mebibyte, std::int64_t>(l); }
-constexpr auto operator"" q_GiB(unsigned long long l) { return information<gibibyte, std::int64_t>(l); }
-constexpr auto operator"" q_TiB(unsigned long long l) { return information<tebibyte, std::int64_t>(l); }
-constexpr auto operator"" q_PiB(unsigned long long l) { return information<pebibyte, std::int64_t>(l); }
+constexpr auto operator"" _q_B(unsigned long long l) { return information<byte, std::int64_t>(l); }
+constexpr auto operator"" _q_KiB(unsigned long long l) { return information<kibibyte, std::int64_t>(l); }
+constexpr auto operator"" _q_MiB(unsigned long long l) { return information<mebibyte, std::int64_t>(l); }
+constexpr auto operator"" _q_GiB(unsigned long long l) { return information<gibibyte, std::int64_t>(l); }
+constexpr auto operator"" _q_TiB(unsigned long long l) { return information<tebibyte, std::int64_t>(l); }
+constexpr auto operator"" _q_PiB(unsigned long long l) { return information<pebibyte, std::int64_t>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/format.h b/src/include/units/format.h
index f400de6f..bb11c973 100644
--- a/src/include/units/format.h
+++ b/src/include/units/format.h
@@ -437,7 +437,7 @@ public:
     fmt::detail::handle_dynamic_spec<fmt::detail::precision_checker>(rep_specs.precision, precision_ref, ctx);
 
     // In `global_format_buffer` we will create a global format string
-    //  e.g. "{:*^10%.1Q_%q}, 1.23q_m" => "{:*^10}"
+    //  e.g. "{:*^10%.1Q_%q}, 1.23_q_m" => "{:*^10}"
     fmt::basic_memory_buffer<CharT> global_format_buffer;
     auto to_gfb = std::back_inserter(global_format_buffer);
     format_to(to_gfb, "{{:");
@@ -466,7 +466,7 @@ public:
 
     // In `quantity_buffer` we will have the representation and the unit formatted according to their
     //  specification, ignoring global specifiers
-    //  e.g. "{:*^10%.1Q_%q}, 1.23q_m" => "1.2_m"
+    //  e.g. "{:*^10%.1Q_%q}, 1.23_q_m" => "1.2_m"
     // TODO Avoid extra copying if width is not specified
     fmt::basic_memory_buffer<CharT> quantity_buffer;
     auto to_quantity_buffer = std::back_inserter(quantity_buffer);
diff --git a/src/include/units/physical/cgs/acceleration.h b/src/include/units/physical/cgs/acceleration.h
index 7c066ad3..9674db81 100644
--- a/src/include/units/physical/cgs/acceleration.h
+++ b/src/include/units/physical/cgs/acceleration.h
@@ -37,8 +37,8 @@ using acceleration = quantity<dim_acceleration, U, Rep>;
 inline namespace literals {
 
 // Gal
-constexpr auto operator"" q_Gal(unsigned long long l) { return acceleration<gal, std::int64_t>(l); }
-constexpr auto operator"" q_Gal(long double l) { return acceleration<gal, long double>(l); }
+constexpr auto operator"" _q_Gal(unsigned long long l) { return acceleration<gal, std::int64_t>(l); }
+constexpr auto operator"" _q_Gal(long double l) { return acceleration<gal, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/cgs/area.h b/src/include/units/physical/cgs/area.h
index bd4e7f0e..0a031b04 100644
--- a/src/include/units/physical/cgs/area.h
+++ b/src/include/units/physical/cgs/area.h
@@ -39,8 +39,8 @@ using area = quantity<dim_area, U, Rep>;
 inline namespace literals {
 
 // cm2
-constexpr auto operator"" q_cm2(unsigned long long l) { return area<square_centimetre, std::int64_t>(l); }
-constexpr auto operator"" q_cm2(long double l) { return area<square_centimetre, long double>(l); }
+constexpr auto operator"" _q_cm2(unsigned long long l) { return area<square_centimetre, std::int64_t>(l); }
+constexpr auto operator"" _q_cm2(long double l) { return area<square_centimetre, long double>(l); }
 
 }
 
diff --git a/src/include/units/physical/cgs/energy.h b/src/include/units/physical/cgs/energy.h
index ef881bac..fac6e985 100644
--- a/src/include/units/physical/cgs/energy.h
+++ b/src/include/units/physical/cgs/energy.h
@@ -39,8 +39,8 @@ using energy = quantity<dim_energy, U, Rep>;
 inline namespace literals {
 
 // erg
-constexpr auto operator"" q_erg(unsigned long long l) { return energy<erg, std::int64_t>(l); }
-constexpr auto operator"" q_erg(long double l) { return energy<erg, long double>(l); }
+constexpr auto operator"" _q_erg(unsigned long long l) { return energy<erg, std::int64_t>(l); }
+constexpr auto operator"" _q_erg(long double l) { return energy<erg, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/cgs/force.h b/src/include/units/physical/cgs/force.h
index 9b9b8ead..6add80de 100644
--- a/src/include/units/physical/cgs/force.h
+++ b/src/include/units/physical/cgs/force.h
@@ -40,8 +40,8 @@ using force = quantity<dim_force, U, Rep>;
 inline namespace literals {
 
 // dyn
-constexpr auto operator"" q_dyn(unsigned long long l) { return force<dyne, std::int64_t>(l); }
-constexpr auto operator"" q_dyn(long double l) { return force<dyne, long double>(l); }
+constexpr auto operator"" _q_dyn(unsigned long long l) { return force<dyne, std::int64_t>(l); }
+constexpr auto operator"" _q_dyn(long double l) { return force<dyne, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/cgs/length.h b/src/include/units/physical/cgs/length.h
index 11092bb7..8417d822 100644
--- a/src/include/units/physical/cgs/length.h
+++ b/src/include/units/physical/cgs/length.h
@@ -38,8 +38,8 @@ using length = quantity<dim_length, U, Rep>;
 inline namespace literals {
 
 // cm
-constexpr auto operator"" q_cm(unsigned long long l) { return length<centimetre, std::int64_t>(l); }
-constexpr auto operator"" q_cm(long double l) { return length<centimetre, long double>(l); }
+constexpr auto operator"" _q_cm(unsigned long long l) { return length<centimetre, std::int64_t>(l); }
+constexpr auto operator"" _q_cm(long double l) { return length<centimetre, long double>(l); }
 
 }
 
diff --git a/src/include/units/physical/cgs/mass.h b/src/include/units/physical/cgs/mass.h
index 5079dea8..aa63253e 100644
--- a/src/include/units/physical/cgs/mass.h
+++ b/src/include/units/physical/cgs/mass.h
@@ -38,8 +38,8 @@ using mass = quantity<dim_mass, U, Rep>;
 inline namespace literals {
 
 // g
-constexpr auto operator"" q_g(unsigned long long l) { return mass<gram, std::int64_t>(l); }
-constexpr auto operator"" q_g(long double l) { return mass<gram, long double>(l); }
+constexpr auto operator"" _q_g(unsigned long long l) { return mass<gram, std::int64_t>(l); }
+constexpr auto operator"" _q_g(long double l) { return mass<gram, long double>(l); }
 
 }
 
diff --git a/src/include/units/physical/cgs/power.h b/src/include/units/physical/cgs/power.h
index a2e1d0e3..2b1b25d7 100644
--- a/src/include/units/physical/cgs/power.h
+++ b/src/include/units/physical/cgs/power.h
@@ -39,8 +39,8 @@ using power = quantity<dim_power, U, Rep>;
 inline namespace literals {
 
 // ergps
-constexpr auto operator"" q_erg_per_s(unsigned long long l) { return power<erg_per_second, std::int64_t>(l); }
-constexpr auto operator"" q_erg_per_s(long double l) { return power<erg_per_second, long double>(l); }
+constexpr auto operator"" _q_erg_per_s(unsigned long long l) { return power<erg_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_erg_per_s(long double l) { return power<erg_per_second, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/cgs/pressure.h b/src/include/units/physical/cgs/pressure.h
index cadd94e3..d96dcd99 100644
--- a/src/include/units/physical/cgs/pressure.h
+++ b/src/include/units/physical/cgs/pressure.h
@@ -40,8 +40,8 @@ using pressure = quantity<dim_pressure, U, Rep>;
 inline namespace literals {
 
 // Ba
-constexpr auto operator"" q_Ba(unsigned long long l) { return pressure<barye, std::int64_t>(l); }
-constexpr auto operator"" q_Ba(long double l) { return pressure<barye, long double>(l); }
+constexpr auto operator"" _q_Ba(unsigned long long l) { return pressure<barye, std::int64_t>(l); }
+constexpr auto operator"" _q_Ba(long double l) { return pressure<barye, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/cgs/speed.h b/src/include/units/physical/cgs/speed.h
index f382daa1..799ccf22 100644
--- a/src/include/units/physical/cgs/speed.h
+++ b/src/include/units/physical/cgs/speed.h
@@ -38,8 +38,8 @@ using speed = quantity<dim_speed, U, Rep>;
 inline namespace literals {
 
 // cmps
-constexpr auto operator"" q_cm_per_s(unsigned long long l) { return speed<centimetre_per_second, std::int64_t>(l); }
-constexpr auto operator"" q_cm_per_s(long double l) { return speed<centimetre_per_second, long double>(l); }
+constexpr auto operator"" _q_cm_per_s(unsigned long long l) { return speed<centimetre_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_cm_per_s(long double l) { return speed<centimetre_per_second, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/cgs/time.h b/src/include/units/physical/cgs/time.h
index 1b5df90a..842fe340 100644
--- a/src/include/units/physical/cgs/time.h
+++ b/src/include/units/physical/cgs/time.h
@@ -35,7 +35,7 @@ using si::time;
 
 inline namespace literals {
 
-using si::literals::operator"" q_s;
+using si::literals::operator"" _q_s;
 
 }
 
diff --git a/src/include/units/physical/fps/acceleration.h b/src/include/units/physical/fps/acceleration.h
index 6917dcdd..daefef02 100644
--- a/src/include/units/physical/fps/acceleration.h
+++ b/src/include/units/physical/fps/acceleration.h
@@ -37,8 +37,8 @@ using acceleration = quantity<dim_acceleration, U, Rep>;
 inline namespace literals {
 
 // ft_per_s2
-constexpr auto operator"" q_ft_per_s2(unsigned long long l) { return acceleration<foot_per_second_sq, std::int64_t>(l); }
-constexpr auto operator"" q_ft_per_s2(long double l) { return acceleration<foot_per_second_sq, long double>(l); }
+constexpr auto operator"" _q_ft_per_s2(unsigned long long l) { return acceleration<foot_per_second_sq, std::int64_t>(l); }
+constexpr auto operator"" _q_ft_per_s2(long double l) { return acceleration<foot_per_second_sq, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/fps/area.h b/src/include/units/physical/fps/area.h
index 107f053d..e886c742 100644
--- a/src/include/units/physical/fps/area.h
+++ b/src/include/units/physical/fps/area.h
@@ -39,8 +39,8 @@ using area = quantity<dim_area, U, Rep>;
 inline namespace literals {
 
 // ft2
-constexpr auto operator"" q_ft2(unsigned long long l) { return area<square_foot, std::int64_t>(l); }
-constexpr auto operator"" q_ft2(long double l) { return area<square_foot, long double>(l); }
+constexpr auto operator"" _q_ft2(unsigned long long l) { return area<square_foot, std::int64_t>(l); }
+constexpr auto operator"" _q_ft2(long double l) { return area<square_foot, long double>(l); }
 
 }
 
diff --git a/src/include/units/physical/fps/density.h b/src/include/units/physical/fps/density.h
index 118c05b5..bee81a0e 100644
--- a/src/include/units/physical/fps/density.h
+++ b/src/include/units/physical/fps/density.h
@@ -38,8 +38,8 @@ using density = quantity<dim_density, U, Rep>;
 
 inline namespace literals {
 
-constexpr auto operator"" q_lb_per_ft3(unsigned long long l) { return density<pound_per_foot_cub, std::int64_t>(l); }
-constexpr auto operator"" q_lb_per_ft3(long double l) { return density<pound_per_foot_cub, long double>(l); }
+constexpr auto operator"" _q_lb_per_ft3(unsigned long long l) { return density<pound_per_foot_cub, std::int64_t>(l); }
+constexpr auto operator"" _q_lb_per_ft3(long double l) { return density<pound_per_foot_cub, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/fps/energy.h b/src/include/units/physical/fps/energy.h
index 2d7f89d8..9b5189a4 100644
--- a/src/include/units/physical/fps/energy.h
+++ b/src/include/units/physical/fps/energy.h
@@ -45,12 +45,12 @@ using energy = quantity<dim_energy, U, Rep>;
 
 inline namespace literals {
 
-constexpr auto operator"" q_ft_pdl(unsigned long long l) { return energy<foot_poundal, std::int64_t>(l); }
-constexpr auto operator"" q_ft_pdl(long double l) { return energy<foot_poundal, long double>(l); }
+constexpr auto operator"" _q_ft_pdl(unsigned long long l) { return energy<foot_poundal, std::int64_t>(l); }
+constexpr auto operator"" _q_ft_pdl(long double l) { return energy<foot_poundal, long double>(l); }
 
 // foot_pound force
-constexpr auto operator"" q_ft_lbf(unsigned long long l) { return energy<foot_pound_force, std::int64_t>(l); }
-constexpr auto operator"" q_ft_lbf(long double l) { return energy<foot_pound_force, long double>(l); }
+constexpr auto operator"" _q_ft_lbf(unsigned long long l) { return energy<foot_pound_force, std::int64_t>(l); }
+constexpr auto operator"" _q_ft_lbf(long double l) { return energy<foot_pound_force, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/fps/force.h b/src/include/units/physical/fps/force.h
index ad6b32c3..30d9a754 100644
--- a/src/include/units/physical/fps/force.h
+++ b/src/include/units/physical/fps/force.h
@@ -49,16 +49,16 @@ using force = quantity<dim_force, U, Rep>;
 inline namespace literals {
 
 // poundal
-constexpr auto operator"" q_pdl(unsigned long long l) { return force<poundal, std::int64_t>(l); }
-constexpr auto operator"" q_pdl(long double l) { return force<poundal, long double>(l); }
+constexpr auto operator"" _q_pdl(unsigned long long l) { return force<poundal, std::int64_t>(l); }
+constexpr auto operator"" _q_pdl(long double l) { return force<poundal, long double>(l); }
 
 // pound force
-constexpr auto operator"" q_lbf(unsigned long long l) { return force<pound_force, std::int64_t>(l); }
-constexpr auto operator"" q_lbf(long double l) { return force<pound_force, long double>(l); }
+constexpr auto operator"" _q_lbf(unsigned long long l) { return force<pound_force, std::int64_t>(l); }
+constexpr auto operator"" _q_lbf(long double l) { return force<pound_force, long double>(l); }
 
 // kilopound force
-constexpr auto operator"" q_klbf(unsigned long long l) { return force<kilopound_force, std::int64_t>(l); }
-constexpr auto operator"" q_klbf(long double l) { return force<kilopound_force, long double>(l); }
+constexpr auto operator"" _q_klbf(unsigned long long l) { return force<kilopound_force, std::int64_t>(l); }
+constexpr auto operator"" _q_klbf(long double l) { return force<kilopound_force, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/fps/length.h b/src/include/units/physical/fps/length.h
index 31f46020..4952e868 100644
--- a/src/include/units/physical/fps/length.h
+++ b/src/include/units/physical/fps/length.h
@@ -58,39 +58,39 @@ using length = quantity<dim_length, U, Rep>;
 inline namespace literals {
 
 // Thousandth
-constexpr auto operator"" q_thou(unsigned long long l) { return length<thousandth, std::int64_t>(l); }
-constexpr auto operator"" q_thou(long double l) { return length<thousandth, long double>(l); }
-constexpr auto operator"" q_mil(unsigned long long l) { return length<thousandth, std::int64_t>(l); }
-constexpr auto operator"" q_mil(long double l) { return length<thousandth, long double>(l); }
+constexpr auto operator"" _q_thou(unsigned long long l) { return length<thousandth, std::int64_t>(l); }
+constexpr auto operator"" _q_thou(long double l) { return length<thousandth, long double>(l); }
+constexpr auto operator"" _q_mil(unsigned long long l) { return length<thousandth, std::int64_t>(l); }
+constexpr auto operator"" _q_mil(long double l) { return length<thousandth, long double>(l); }
 
 
 // Inch
-constexpr auto operator"" q_in(unsigned long long l) { return length<inch, std::int64_t>(l); }
-constexpr auto operator"" q_in(long double l) { return length<inch, long double>(l); }
+constexpr auto operator"" _q_in(unsigned long long l) { return length<inch, std::int64_t>(l); }
+constexpr auto operator"" _q_in(long double l) { return length<inch, long double>(l); }
 
 // Foot
-constexpr auto operator"" q_ft(unsigned long long l) { return length<foot, std::int64_t>(l); }
-constexpr auto operator"" q_ft(long double l) { return length<foot, long double>(l); }
+constexpr auto operator"" _q_ft(unsigned long long l) { return length<foot, std::int64_t>(l); }
+constexpr auto operator"" _q_ft(long double l) { return length<foot, long double>(l); }
 
 // Yard
-constexpr auto operator"" q_yd(unsigned long long l) { return length<yard, std::int64_t>(l); }
-constexpr auto operator"" q_yd(long double l) { return length<yard, long double>(l); }
+constexpr auto operator"" _q_yd(unsigned long long l) { return length<yard, std::int64_t>(l); }
+constexpr auto operator"" _q_yd(long double l) { return length<yard, long double>(l); }
 
 // Fathom
-constexpr auto operator"" q_ftm(unsigned long long l) { return length<fathom, std::int64_t>(l); }
-constexpr auto operator"" q_ftm(long double l) { return length<fathom, long double>(l); }
+constexpr auto operator"" _q_ftm(unsigned long long l) { return length<fathom, std::int64_t>(l); }
+constexpr auto operator"" _q_ftm(long double l) { return length<fathom, long double>(l); }
 
 // Kiloyard
-constexpr auto operator"" q_kyd(unsigned long long l) { return length<kiloyard, std::int64_t>(l); }
-constexpr auto operator"" q_kyd(long double l) { return length<kiloyard, long double>(l); }
+constexpr auto operator"" _q_kyd(unsigned long long l) { return length<kiloyard, std::int64_t>(l); }
+constexpr auto operator"" _q_kyd(long double l) { return length<kiloyard, long double>(l); }
 
 // Mile
-constexpr auto operator"" q_mile(unsigned long long l) { return length<mile, std::int64_t>(l); }
-constexpr auto operator"" q_mile(long double l) { return length<mile, long double>(l); }
+constexpr auto operator"" _q_mile(unsigned long long l) { return length<mile, std::int64_t>(l); }
+constexpr auto operator"" _q_mile(long double l) { return length<mile, long double>(l); }
 
 // Nautical mile
-constexpr auto operator"" q_naut_mi(unsigned long long l) { return length<nautical_mile, std::int64_t>(l); }
-constexpr auto operator"" q_naut_mi(long double l) { return length<nautical_mile, long double>(l); }
+constexpr auto operator"" _q_naut_mi(unsigned long long l) { return length<nautical_mile, std::int64_t>(l); }
+constexpr auto operator"" _q_naut_mi(long double l) { return length<nautical_mile, long double>(l); }
 
 
 }
diff --git a/src/include/units/physical/fps/mass.h b/src/include/units/physical/fps/mass.h
index 3802035f..614d73c3 100644
--- a/src/include/units/physical/fps/mass.h
+++ b/src/include/units/physical/fps/mass.h
@@ -55,40 +55,40 @@ struct long_ton : named_scaled_unit<long_ton, "ton (long)", no_prefix, ratio(2'2
 inline namespace literals {
 
 // Grain
-constexpr auto operator"" q_gr(unsigned long long l) { return mass<grain, std::int64_t>(l); }
-constexpr auto operator"" q_gr(long double l) { return mass<grain, long double>(l); }
+constexpr auto operator"" _q_gr(unsigned long long l) { return mass<grain, std::int64_t>(l); }
+constexpr auto operator"" _q_gr(long double l) { return mass<grain, long double>(l); }
 
 // Dram
-constexpr auto operator"" q_dr(unsigned long long l) { return mass<dram, std::int64_t>(l); }
-constexpr auto operator"" q_dr(long double l) { return mass<dram, long double>(l); }
+constexpr auto operator"" _q_dr(unsigned long long l) { return mass<dram, std::int64_t>(l); }
+constexpr auto operator"" _q_dr(long double l) { return mass<dram, long double>(l); }
 
 // Ounce
-constexpr auto operator"" q_oz(unsigned long long l) { return mass<ounce, std::int64_t>(l); }
-constexpr auto operator"" q_oz(long double l) { return mass<ounce, long double>(l); }
+constexpr auto operator"" _q_oz(unsigned long long l) { return mass<ounce, std::int64_t>(l); }
+constexpr auto operator"" _q_oz(long double l) { return mass<ounce, long double>(l); }
 
 // Pound
-constexpr auto operator"" q_lb(unsigned long long l) { return mass<pound, std::int64_t>(l); }
-constexpr auto operator"" q_lb(long double l) { return mass<pound, long double>(l); }
+constexpr auto operator"" _q_lb(unsigned long long l) { return mass<pound, std::int64_t>(l); }
+constexpr auto operator"" _q_lb(long double l) { return mass<pound, long double>(l); }
 
 // Stone
-constexpr auto operator"" q_st(unsigned long long l) { return mass<stone, std::int64_t>(l); }
-constexpr auto operator"" q_st(long double l) { return mass<stone, long double>(l); }
+constexpr auto operator"" _q_st(unsigned long long l) { return mass<stone, std::int64_t>(l); }
+constexpr auto operator"" _q_st(long double l) { return mass<stone, long double>(l); }
 
 // Quarter
-constexpr auto operator"" q_qr(unsigned long long l) { return mass<quarter, std::int64_t>(l); }
-constexpr auto operator"" q_qr(long double l) { return mass<quarter, long double>(l); }
+constexpr auto operator"" _q_qr(unsigned long long l) { return mass<quarter, std::int64_t>(l); }
+constexpr auto operator"" _q_qr(long double l) { return mass<quarter, long double>(l); }
 
 // Hundredweight
-constexpr auto operator"" q_cwt(unsigned long long l) { return mass<hundredweight, std::int64_t>(l); }
-constexpr auto operator"" q_cwt(long double l) { return mass<hundredweight, long double>(l); }
+constexpr auto operator"" _q_cwt(unsigned long long l) { return mass<hundredweight, std::int64_t>(l); }
+constexpr auto operator"" _q_cwt(long double l) { return mass<hundredweight, long double>(l); }
 
 // Short ton
-constexpr auto operator"" q_ston(unsigned long long l) { return mass<short_ton, std::int64_t>(l); }
-constexpr auto operator"" q_ston(long double l) { return mass<short_ton, long double>(l); }
+constexpr auto operator"" _q_ston(unsigned long long l) { return mass<short_ton, std::int64_t>(l); }
+constexpr auto operator"" _q_ston(long double l) { return mass<short_ton, long double>(l); }
 
 // Long Ton
-constexpr auto operator"" q_lton(unsigned long long l) { return mass<long_ton, std::int64_t>(l); }
-constexpr auto operator"" q_lton(long double l) { return mass<long_ton, long double>(l); }
+constexpr auto operator"" _q_lton(unsigned long long l) { return mass<long_ton, std::int64_t>(l); }
+constexpr auto operator"" _q_lton(long double l) { return mass<long_ton, long double>(l); }
 
 
 }
diff --git a/src/include/units/physical/fps/power.h b/src/include/units/physical/fps/power.h
index 6a6a320f..dcaf1be3 100644
--- a/src/include/units/physical/fps/power.h
+++ b/src/include/units/physical/fps/power.h
@@ -43,17 +43,17 @@ using power = quantity<dim_power, U, Rep>;
 inline namespace literals {
 
 // foot pound force per second
-constexpr auto operator"" q_ft_pdl_per_s(unsigned long long l) { return power<foot_poundal_per_second, std::int64_t>(l); }
-constexpr auto operator"" q_ft_pdl_per_s(long double l) { return power<foot_poundal_per_second, long double>(l); }
+constexpr auto operator"" _q_ft_pdl_per_s(unsigned long long l) { return power<foot_poundal_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_ft_pdl_per_s(long double l) { return power<foot_poundal_per_second, long double>(l); }
 
 
 // foot pound force per second
-constexpr auto operator"" q_ft_lbf_per_s(unsigned long long l) { return power<foot_pound_force_per_second, std::int64_t>(l); }
-constexpr auto operator"" q_ft_lbf_per_s(long double l) { return power<foot_pound_force_per_second, long double>(l); }
+constexpr auto operator"" _q_ft_lbf_per_s(unsigned long long l) { return power<foot_pound_force_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_ft_lbf_per_s(long double l) { return power<foot_pound_force_per_second, long double>(l); }
 
 
-constexpr auto operator"" q_hp(unsigned long long l) { return power<horse_power, std::int64_t>(l); }
-constexpr auto operator"" q_hp(long double l) { return power<horse_power, long double>(l); }
+constexpr auto operator"" _q_hp(unsigned long long l) { return power<horse_power, std::int64_t>(l); }
+constexpr auto operator"" _q_hp(long double l) { return power<horse_power, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/fps/pressure.h b/src/include/units/physical/fps/pressure.h
index a9760bc9..bb710921 100644
--- a/src/include/units/physical/fps/pressure.h
+++ b/src/include/units/physical/fps/pressure.h
@@ -45,16 +45,16 @@ struct kilopound_force_per_inch_sq : prefixed_unit<kilopound_force_per_inch_sq,
 
 inline namespace literals {
 // Poundal per square foot
-constexpr auto operator"" q_pdl_per_ft2(unsigned long long l) { return pressure<poundal_per_foot_sq, std::int64_t>(l); }
-constexpr auto operator"" q_pdl_per_ft2(long double l) { return pressure<poundal_per_foot_sq, long double>(l); }
+constexpr auto operator"" _q_pdl_per_ft2(unsigned long long l) { return pressure<poundal_per_foot_sq, std::int64_t>(l); }
+constexpr auto operator"" _q_pdl_per_ft2(long double l) { return pressure<poundal_per_foot_sq, long double>(l); }
 
 // Pounds per square inch
-constexpr auto operator"" q_psi(unsigned long long l) { return pressure<pound_force_per_inch_sq, std::int64_t>(l); }
-constexpr auto operator"" q_psi(long double l) { return pressure<pound_force_per_inch_sq, long double>(l); }
+constexpr auto operator"" _q_psi(unsigned long long l) { return pressure<pound_force_per_inch_sq, std::int64_t>(l); }
+constexpr auto operator"" _q_psi(long double l) { return pressure<pound_force_per_inch_sq, long double>(l); }
 
 // kilopounds per square inch
-constexpr auto operator"" q_kpsi(unsigned long long l) { return pressure<kilopound_force_per_inch_sq, std::int64_t>(l); }
-constexpr auto operator"" q_kpsi(long double l) { return pressure<kilopound_force_per_inch_sq, long double>(l); }
+constexpr auto operator"" _q_kpsi(unsigned long long l) { return pressure<kilopound_force_per_inch_sq, std::int64_t>(l); }
+constexpr auto operator"" _q_kpsi(long double l) { return pressure<kilopound_force_per_inch_sq, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/fps/speed.h b/src/include/units/physical/fps/speed.h
index 8de37c0a..562afb8e 100644
--- a/src/include/units/physical/fps/speed.h
+++ b/src/include/units/physical/fps/speed.h
@@ -44,14 +44,14 @@ struct knot : alias_unit<nautical_mile_per_hour, "knot", no_prefix> {};
 
 inline namespace literals {
 
-constexpr auto operator"" q_ft_per_s(unsigned long long l) { return speed<foot_per_second, std::int64_t>(l); }
-constexpr auto operator"" q_ft_per_s(long double l) { return speed<foot_per_second, long double>(l); }
+constexpr auto operator"" _q_ft_per_s(unsigned long long l) { return speed<foot_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_ft_per_s(long double l) { return speed<foot_per_second, long double>(l); }
 
-constexpr auto operator"" q_mph(unsigned long long l) { return speed<mile_per_hour, std::int64_t>(l); }
-constexpr auto operator"" q_mph(long double l) { return speed<mile_per_hour, long double>(l); }
+constexpr auto operator"" _q_mph(unsigned long long l) { return speed<mile_per_hour, std::int64_t>(l); }
+constexpr auto operator"" _q_mph(long double l) { return speed<mile_per_hour, long double>(l); }
 
-constexpr auto operator"" q_knot(unsigned long long l) { return speed<knot, std::int64_t>(l); }
-constexpr auto operator"" q_knot(long double l) { return speed<knot, long double>(l); }
+constexpr auto operator"" _q_knot(unsigned long long l) { return speed<knot, std::int64_t>(l); }
+constexpr auto operator"" _q_knot(long double l) { return speed<knot, long double>(l); }
 
 
 }  // namespace literals
diff --git a/src/include/units/physical/fps/time.h b/src/include/units/physical/fps/time.h
index 4862c736..fa622e0e 100644
--- a/src/include/units/physical/fps/time.h
+++ b/src/include/units/physical/fps/time.h
@@ -37,7 +37,7 @@ using si::time;
 
 inline namespace literals {
 
-using si::literals::operator"" q_s;
+using si::literals::operator"" _q_s;
 
 }
 
diff --git a/src/include/units/physical/fps/volume.h b/src/include/units/physical/fps/volume.h
index 57e49c1a..4c6f4e42 100644
--- a/src/include/units/physical/fps/volume.h
+++ b/src/include/units/physical/fps/volume.h
@@ -39,12 +39,12 @@ using volume = quantity<dim_volume, U, Rep>;
 inline namespace literals {
 
 // ft3
-constexpr auto operator"" q_ft3(unsigned long long l) { return volume<cubic_foot, std::int64_t>(l); }
-constexpr auto operator"" q_ft3(long double l) { return volume<cubic_foot, long double>(l); }
+constexpr auto operator"" _q_ft3(unsigned long long l) { return volume<cubic_foot, std::int64_t>(l); }
+constexpr auto operator"" _q_ft3(long double l) { return volume<cubic_foot, long double>(l); }
 
 // yard3
-constexpr auto operator"" q_yd3(unsigned long long l) { return volume<cubic_yard, std::int64_t>(l); }
-constexpr auto operator"" q_yd3(long double l) { return volume<cubic_yard, long double>(l); }
+constexpr auto operator"" _q_yd3(unsigned long long l) { return volume<cubic_yard, std::int64_t>(l); }
+constexpr auto operator"" _q_yd3(long double l) { return volume<cubic_yard, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/iau/length.h b/src/include/units/physical/iau/length.h
index 0786dcbc..a7284e38 100644
--- a/src/include/units/physical/iau/length.h
+++ b/src/include/units/physical/iau/length.h
@@ -38,14 +38,14 @@ struct angstrom : named_scaled_unit<angstrom, "angstrom", no_prefix, ratio(1, 1,
 
 inline namespace literals {
 
-constexpr auto operator"" q_ly(unsigned long long l) { return si::length<light_year, std::int64_t>(l); }
-constexpr auto operator"" q_ly(long double l) { return si::length<light_year, long double>(l); }
+constexpr auto operator"" _q_ly(unsigned long long l) { return si::length<light_year, std::int64_t>(l); }
+constexpr auto operator"" _q_ly(long double l) { return si::length<light_year, long double>(l); }
 
-constexpr auto operator"" q_pc(unsigned long long l) { return si::length<parsec, std::int64_t>(l); }
-constexpr auto operator"" q_pc(long double l) { return si::length<parsec, long double>(l); }
+constexpr auto operator"" _q_pc(unsigned long long l) { return si::length<parsec, std::int64_t>(l); }
+constexpr auto operator"" _q_pc(long double l) { return si::length<parsec, long double>(l); }
 
-constexpr auto operator"" q_angstrom(unsigned long long l) { return si::length<angstrom, std::int64_t>(l); }
-constexpr auto operator"" q_angstrom(long double l) { return si::length<angstrom, long double>(l); }
+constexpr auto operator"" _q_angstrom(unsigned long long l) { return si::length<angstrom, std::int64_t>(l); }
+constexpr auto operator"" _q_angstrom(long double l) { return si::length<angstrom, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/imperial/length.h b/src/include/units/physical/imperial/length.h
index cbe856a9..1c1273a0 100644
--- a/src/include/units/physical/imperial/length.h
+++ b/src/include/units/physical/imperial/length.h
@@ -34,11 +34,11 @@ struct rod : named_scaled_unit<rod, "rd", no_prefix, ratio(1, 4), chain> {};
 
 inline namespace literals {
 
-constexpr auto operator"" q_ch(unsigned long long l) { return si::length<chain, std::int64_t>(l); }
-constexpr auto operator"" q_ch(long double l) { return si::length<chain, long double>(l); }
+constexpr auto operator"" _q_ch(unsigned long long l) { return si::length<chain, std::int64_t>(l); }
+constexpr auto operator"" _q_ch(long double l) { return si::length<chain, long double>(l); }
 
-constexpr auto operator"" q_rd(unsigned long long l) { return si::length<rod, std::int64_t>(l); }
-constexpr auto operator"" q_rd(long double l) { return si::length<rod, long double>(l); }
+constexpr auto operator"" _q_rd(unsigned long long l) { return si::length<rod, std::int64_t>(l); }
+constexpr auto operator"" _q_rd(long double l) { return si::length<rod, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/international/area.h b/src/include/units/physical/international/area.h
index 65686c3d..7fa51c42 100644
--- a/src/include/units/physical/international/area.h
+++ b/src/include/units/physical/international/area.h
@@ -32,8 +32,8 @@ struct square_foot : deduced_unit<square_foot, si::dim_area, international::foot
 inline namespace literals {
 
 // ft2
-constexpr auto operator"" q_ft2(unsigned long long l) { return si::area<square_foot, std::int64_t>(l); }
-constexpr auto operator"" q_ft2(long double l) { return si::area<square_foot, long double>(l); }
+constexpr auto operator"" _q_ft2(unsigned long long l) { return si::area<square_foot, std::int64_t>(l); }
+constexpr auto operator"" _q_ft2(long double l) { return si::area<square_foot, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/international/length.h b/src/include/units/physical/international/length.h
index 74a0f223..2e7d3a41 100644
--- a/src/include/units/physical/international/length.h
+++ b/src/include/units/physical/international/length.h
@@ -61,36 +61,36 @@ using mil = thou;
 inline namespace literals {
 
 // yd
-constexpr auto operator"" q_yd(unsigned long long l) { return si::length<yard, std::int64_t>(l); }
-constexpr auto operator"" q_yd(long double l) { return si::length<yard, long double>(l); }
+constexpr auto operator"" _q_yd(unsigned long long l) { return si::length<yard, std::int64_t>(l); }
+constexpr auto operator"" _q_yd(long double l) { return si::length<yard, long double>(l); }
 
 // ft
-constexpr auto operator"" q_ft(unsigned long long l) { return si::length<foot, std::int64_t>(l); }
-constexpr auto operator"" q_ft(long double l) { return si::length<foot, long double>(l); }
+constexpr auto operator"" _q_ft(unsigned long long l) { return si::length<foot, std::int64_t>(l); }
+constexpr auto operator"" _q_ft(long double l) { return si::length<foot, long double>(l); }
 
 // fathom
-constexpr auto operator"" q_fathom(unsigned long long l) { return si::length<fathom, std::int64_t>(l); }
-constexpr auto operator"" q_fathom(long double l) { return si::length<fathom, long double>(l); }
+constexpr auto operator"" _q_fathom(unsigned long long l) { return si::length<fathom, std::int64_t>(l); }
+constexpr auto operator"" _q_fathom(long double l) { return si::length<fathom, long double>(l); }
 
 // in
-constexpr auto operator"" q_in(unsigned long long l) { return si::length<inch, std::int64_t>(l); }
-constexpr auto operator"" q_in(long double l) { return si::length<inch, long double>(l); }
+constexpr auto operator"" _q_in(unsigned long long l) { return si::length<inch, std::int64_t>(l); }
+constexpr auto operator"" _q_in(long double l) { return si::length<inch, long double>(l); }
 
 // mi
-constexpr auto operator"" q_mi(unsigned long long l) { return si::length<mile, std::int64_t>(l); }
-constexpr auto operator"" q_mi(long double l) { return si::length<mile, long double>(l); }
+constexpr auto operator"" _q_mi(unsigned long long l) { return si::length<mile, std::int64_t>(l); }
+constexpr auto operator"" _q_mi(long double l) { return si::length<mile, long double>(l); }
 
 // mi_naut
-constexpr auto operator"" q_naut_mi(unsigned long long l) { return si::length<nautical_mile, std::int64_t>(l); }
-constexpr auto operator"" q_naut_mi(long double l) { return si::length<nautical_mile, long double>(l); }
+constexpr auto operator"" _q_naut_mi(unsigned long long l) { return si::length<nautical_mile, std::int64_t>(l); }
+constexpr auto operator"" _q_naut_mi(long double l) { return si::length<nautical_mile, long double>(l); }
 
 // thou
-constexpr auto operator"" q_thou(unsigned long long l) { return si::length<thou, std::int64_t>(l); }
-constexpr auto operator"" q_thou(long double l) { return si::length<thou, long double>(l); }
+constexpr auto operator"" _q_thou(unsigned long long l) { return si::length<thou, std::int64_t>(l); }
+constexpr auto operator"" _q_thou(long double l) { return si::length<thou, long double>(l); }
 
 // mil
-constexpr auto operator"" q_mil(unsigned long long l) { return si::length<mil, std::int64_t>(l); }
-constexpr auto operator"" q_mil(long double l) { return si::length<mil, long double>(l); }
+constexpr auto operator"" _q_mil(unsigned long long l) { return si::length<mil, std::int64_t>(l); }
+constexpr auto operator"" _q_mil(long double l) { return si::length<mil, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/international/speed.h b/src/include/units/physical/international/speed.h
index 89c09c56..602c387a 100644
--- a/src/include/units/physical/international/speed.h
+++ b/src/include/units/physical/international/speed.h
@@ -32,8 +32,8 @@ struct mile_per_hour : deduced_unit<mile_per_hour, si::dim_speed, international:
 inline namespace literals {
 
 // mph
-constexpr auto operator"" q_mi_per_h(unsigned long long l) { return si::speed<mile_per_hour, std::int64_t>(l); }
-constexpr auto operator"" q_mi_per_h(long double l) { return si::speed<mile_per_hour, long double>(l); }
+constexpr auto operator"" _q_mi_per_h(unsigned long long l) { return si::speed<mile_per_hour, std::int64_t>(l); }
+constexpr auto operator"" _q_mi_per_h(long double l) { return si::speed<mile_per_hour, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/international/volume.h b/src/include/units/physical/international/volume.h
index 82f753d6..a4dfe817 100644
--- a/src/include/units/physical/international/volume.h
+++ b/src/include/units/physical/international/volume.h
@@ -32,8 +32,8 @@ struct cubic_foot : deduced_unit<cubic_foot, si::dim_volume, international::foot
 inline namespace literals {
 
 // ft3
-constexpr auto operator"" q_ft3(unsigned long long l) { return si::volume<cubic_foot, std::int64_t>(l); }
-constexpr auto operator"" q_ft3(long double l) { return si::volume<cubic_foot, long double>(l); }
+constexpr auto operator"" _q_ft3(unsigned long long l) { return si::volume<cubic_foot, std::int64_t>(l); }
+constexpr auto operator"" _q_ft3(long double l) { return si::volume<cubic_foot, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/natural/dimensions.h b/src/include/units/physical/natural/dimensions.h
index d4291bda..3241ee4e 100644
--- a/src/include/units/physical/natural/dimensions.h
+++ b/src/include/units/physical/natural/dimensions.h
@@ -61,6 +61,6 @@ template<Unit U, ScalableNumber Rep = double>
 using energy = quantity<dim_force, U, Rep>;
 
 // Typical UDLs will not work here as the same units are reused by many quantities.
-// Should we define some strange ones (i.e. q_mass_GeV)?
+// Should we define some strange ones (i.e. _q_mass_GeV)?
 
 }  // namespace units::physical::natural
diff --git a/src/include/units/physical/si/absorbed_dose.h b/src/include/units/physical/si/absorbed_dose.h
index 9c2e88c5..fa653710 100644
--- a/src/include/units/physical/si/absorbed_dose.h
+++ b/src/include/units/physical/si/absorbed_dose.h
@@ -60,88 +60,88 @@ using absorbed_dose = quantity<dim_absorbed_dose, U, Rep>;
 inline namespace literals {
 
 // G
-constexpr auto operator"" q_Gy(unsigned long long l) { return absorbed_dose<gray, std::int64_t>(l); }
-constexpr auto operator"" q_Gy(long double l) { return absorbed_dose<gray, long double>(l); }
+constexpr auto operator"" _q_Gy(unsigned long long l) { return absorbed_dose<gray, std::int64_t>(l); }
+constexpr auto operator"" _q_Gy(long double l) { return absorbed_dose<gray, long double>(l); }
 
 // yGy
-constexpr auto operator"" q_yGy(unsigned long long l) { return absorbed_dose<yoctogray, std::int64_t>(l); }
-constexpr auto operator"" q_yGy(long double l) { return absorbed_dose<yoctogray, long double>(l); }
+constexpr auto operator"" _q_yGy(unsigned long long l) { return absorbed_dose<yoctogray, std::int64_t>(l); }
+constexpr auto operator"" _q_yGy(long double l) { return absorbed_dose<yoctogray, long double>(l); }
 
 // zGy
-constexpr auto operator"" q_zGy(unsigned long long l) { return absorbed_dose<zeptogray, std::int64_t>(l); }
-constexpr auto operator"" q_zGy(long double l) { return absorbed_dose<zeptogray, long double>(l); }
+constexpr auto operator"" _q_zGy(unsigned long long l) { return absorbed_dose<zeptogray, std::int64_t>(l); }
+constexpr auto operator"" _q_zGy(long double l) { return absorbed_dose<zeptogray, long double>(l); }
 
 // aGy
-constexpr auto operator"" q_aGy(unsigned long long l) { return absorbed_dose<attogray, std::int64_t>(l); }
-constexpr auto operator"" q_aGy(long double l) { return absorbed_dose<attogray, long double>(l); }
+constexpr auto operator"" _q_aGy(unsigned long long l) { return absorbed_dose<attogray, std::int64_t>(l); }
+constexpr auto operator"" _q_aGy(long double l) { return absorbed_dose<attogray, long double>(l); }
 
 // fGy
-constexpr auto operator"" q_fGy(unsigned long long l) { return absorbed_dose<femtogray, std::int64_t>(l); }
-constexpr auto operator"" q_fGy(long double l) { return absorbed_dose<femtogray, long double>(l); }
+constexpr auto operator"" _q_fGy(unsigned long long l) { return absorbed_dose<femtogray, std::int64_t>(l); }
+constexpr auto operator"" _q_fGy(long double l) { return absorbed_dose<femtogray, long double>(l); }
 
 // pGy
-constexpr auto operator"" q_pGy(unsigned long long l) { return absorbed_dose<picogray, std::int64_t>(l); }
-constexpr auto operator"" q_pGy(long double l) { return absorbed_dose<picogray, long double>(l); }
+constexpr auto operator"" _q_pGy(unsigned long long l) { return absorbed_dose<picogray, std::int64_t>(l); }
+constexpr auto operator"" _q_pGy(long double l) { return absorbed_dose<picogray, long double>(l); }
 
 // nGy
-constexpr auto operator"" q_nGy(unsigned long long l) { return absorbed_dose<nanogray, std::int64_t>(l); }
-constexpr auto operator"" q_nGy(long double l) { return absorbed_dose<nanogray, long double>(l); }
+constexpr auto operator"" _q_nGy(unsigned long long l) { return absorbed_dose<nanogray, std::int64_t>(l); }
+constexpr auto operator"" _q_nGy(long double l) { return absorbed_dose<nanogray, long double>(l); }
 
 // uGy
-constexpr auto operator"" q_uGy(unsigned long long l) { return absorbed_dose<microgray, std::int64_t>(l); }
-constexpr auto operator"" q_uGy(long double l) { return absorbed_dose<microgray, long double>(l); }
+constexpr auto operator"" _q_uGy(unsigned long long l) { return absorbed_dose<microgray, std::int64_t>(l); }
+constexpr auto operator"" _q_uGy(long double l) { return absorbed_dose<microgray, long double>(l); }
 
 // mGy
-constexpr auto operator"" q_mGy(unsigned long long l) { return absorbed_dose<milligray, std::int64_t>(l); }
-constexpr auto operator"" q_mGy(long double l) { return absorbed_dose<milligray, long double>(l); }
+constexpr auto operator"" _q_mGy(unsigned long long l) { return absorbed_dose<milligray, std::int64_t>(l); }
+constexpr auto operator"" _q_mGy(long double l) { return absorbed_dose<milligray, long double>(l); }
 
 // cGy
-constexpr auto operator"" q_cGy(unsigned long long l) { return absorbed_dose<centigray, std::int64_t>(l); }
-constexpr auto operator"" q_cGy(long double l) { return absorbed_dose<centigray, long double>(l); }
+constexpr auto operator"" _q_cGy(unsigned long long l) { return absorbed_dose<centigray, std::int64_t>(l); }
+constexpr auto operator"" _q_cGy(long double l) { return absorbed_dose<centigray, long double>(l); }
 
 // dGy
-constexpr auto operator"" q_dGy(unsigned long long l) { return absorbed_dose<decigray, std::int64_t>(l); }
-constexpr auto operator"" q_dGy(long double l) { return absorbed_dose<decigray, long double>(l); }
+constexpr auto operator"" _q_dGy(unsigned long long l) { return absorbed_dose<decigray, std::int64_t>(l); }
+constexpr auto operator"" _q_dGy(long double l) { return absorbed_dose<decigray, long double>(l); }
 
 // daGy
-constexpr auto operator"" q_daGy(unsigned long long l) { return absorbed_dose<decagray, std::int64_t>(l); }
-constexpr auto operator"" q_daGy(long double l) { return absorbed_dose<decagray, long double>(l); }
+constexpr auto operator"" _q_daGy(unsigned long long l) { return absorbed_dose<decagray, std::int64_t>(l); }
+constexpr auto operator"" _q_daGy(long double l) { return absorbed_dose<decagray, long double>(l); }
 
 // hGy
-constexpr auto operator"" q_hGy(unsigned long long l) { return absorbed_dose<hectogray, std::int64_t>(l); }
-constexpr auto operator"" q_hGy(long double l) { return absorbed_dose<hectogray, long double>(l); }
+constexpr auto operator"" _q_hGy(unsigned long long l) { return absorbed_dose<hectogray, std::int64_t>(l); }
+constexpr auto operator"" _q_hGy(long double l) { return absorbed_dose<hectogray, long double>(l); }
 
 // kGy
-constexpr auto operator"" q_kGy(unsigned long long l) { return absorbed_dose<kilogray, std::int64_t>(l); }
-constexpr auto operator"" q_kGy(long double l) { return absorbed_dose<kilogray, long double>(l); }
+constexpr auto operator"" _q_kGy(unsigned long long l) { return absorbed_dose<kilogray, std::int64_t>(l); }
+constexpr auto operator"" _q_kGy(long double l) { return absorbed_dose<kilogray, long double>(l); }
 
 // MGy
-constexpr auto operator"" q_MGy(unsigned long long l) { return absorbed_dose<megagray, std::int64_t>(l); }
-constexpr auto operator"" q_MGy(long double l) { return absorbed_dose<megagray, long double>(l); }
+constexpr auto operator"" _q_MGy(unsigned long long l) { return absorbed_dose<megagray, std::int64_t>(l); }
+constexpr auto operator"" _q_MGy(long double l) { return absorbed_dose<megagray, long double>(l); }
 
 // GGy
-constexpr auto operator"" q_GGy(unsigned long long l) { return absorbed_dose<gigagray, std::int64_t>(l); }
-constexpr auto operator"" q_GGy(long double l) { return absorbed_dose<gigagray, long double>(l); }
+constexpr auto operator"" _q_GGy(unsigned long long l) { return absorbed_dose<gigagray, std::int64_t>(l); }
+constexpr auto operator"" _q_GGy(long double l) { return absorbed_dose<gigagray, long double>(l); }
 
 // TGy
-constexpr auto operator"" q_TGy(unsigned long long l) { return absorbed_dose<teragray, std::int64_t>(l); }
-constexpr auto operator"" q_TGy(long double l) { return absorbed_dose<teragray, long double>(l); }
+constexpr auto operator"" _q_TGy(unsigned long long l) { return absorbed_dose<teragray, std::int64_t>(l); }
+constexpr auto operator"" _q_TGy(long double l) { return absorbed_dose<teragray, long double>(l); }
 
 // PGy
-constexpr auto operator"" q_PGy(unsigned long long l) { return absorbed_dose<petagray, std::int64_t>(l); }
-constexpr auto operator"" q_PGy(long double l) { return absorbed_dose<petagray, long double>(l); }
+constexpr auto operator"" _q_PGy(unsigned long long l) { return absorbed_dose<petagray, std::int64_t>(l); }
+constexpr auto operator"" _q_PGy(long double l) { return absorbed_dose<petagray, long double>(l); }
 
 // EGy
-constexpr auto operator"" q_EGy(unsigned long long l) { return absorbed_dose<exagray, std::int64_t>(l); }
-constexpr auto operator"" q_EGy(long double l) { return absorbed_dose<exagray, long double>(l); }
+constexpr auto operator"" _q_EGy(unsigned long long l) { return absorbed_dose<exagray, std::int64_t>(l); }
+constexpr auto operator"" _q_EGy(long double l) { return absorbed_dose<exagray, long double>(l); }
 
 // ZGy
-constexpr auto operator"" q_ZGy(unsigned long long l) { return absorbed_dose<zettagray, std::int64_t>(l); }
-constexpr auto operator"" q_ZGy(long double l) { return absorbed_dose<zettagray, long double>(l); }
+constexpr auto operator"" _q_ZGy(unsigned long long l) { return absorbed_dose<zettagray, std::int64_t>(l); }
+constexpr auto operator"" _q_ZGy(long double l) { return absorbed_dose<zettagray, long double>(l); }
 
 // YGy
-constexpr auto operator"" q_YGy(unsigned long long l) { return absorbed_dose<yottagray, std::int64_t>(l); }
-constexpr auto operator"" q_YGy(long double l) { return absorbed_dose<yottagray, long double>(l); }
+constexpr auto operator"" _q_YGy(unsigned long long l) { return absorbed_dose<yottagray, std::int64_t>(l); }
+constexpr auto operator"" _q_YGy(long double l) { return absorbed_dose<yottagray, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/acceleration.h b/src/include/units/physical/si/acceleration.h
index ca049a35..0d96c4a6 100644
--- a/src/include/units/physical/si/acceleration.h
+++ b/src/include/units/physical/si/acceleration.h
@@ -37,8 +37,8 @@ using acceleration = quantity<dim_acceleration, U, Rep>;
 inline namespace literals {
 
 // mps2
-constexpr auto operator"" q_m_per_s2(unsigned long long l) { return acceleration<metre_per_second_sq, std::int64_t>(l); }
-constexpr auto operator"" q_m_per_s2(long double l) { return acceleration<metre_per_second_sq, long double>(l); }
+constexpr auto operator"" _q_m_per_s2(unsigned long long l) { return acceleration<metre_per_second_sq, std::int64_t>(l); }
+constexpr auto operator"" _q_m_per_s2(long double l) { return acceleration<metre_per_second_sq, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/angle.h b/src/include/units/physical/si/angle.h
index b2114cfb..a86c18be 100644
--- a/src/include/units/physical/si/angle.h
+++ b/src/include/units/physical/si/angle.h
@@ -38,8 +38,8 @@ using angle = quantity<dim_angle, U, Rep>;
 inline namespace literals {
 
 // rad
-constexpr auto operator"" q_rad(unsigned long long l) { return angle<radian, std::int64_t>(l); }
-constexpr auto operator"" q_rad(long double l) { return angle<radian, long double>(l); }
+constexpr auto operator"" _q_rad(unsigned long long l) { return angle<radian, std::int64_t>(l); }
+constexpr auto operator"" _q_rad(long double l) { return angle<radian, long double>(l); }
 
 
 }  // namespace literals
diff --git a/src/include/units/physical/si/angular_velocity.h b/src/include/units/physical/si/angular_velocity.h
index 924027dc..4b48fb70 100644
--- a/src/include/units/physical/si/angular_velocity.h
+++ b/src/include/units/physical/si/angular_velocity.h
@@ -40,8 +40,8 @@ using angular_velocity = quantity<dim_angular_velocity, U, Rep>;
 inline namespace literals {
 
 // rad / s
-constexpr auto operator"" q_rad_per_s(unsigned long long l) { return angular_velocity<radian_per_second, std::int64_t>(l); }
-constexpr auto operator"" q_rad_per_s(long double l) { return angular_velocity<radian_per_second, long double>(l); }
+constexpr auto operator"" _q_rad_per_s(unsigned long long l) { return angular_velocity<radian_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_rad_per_s(long double l) { return angular_velocity<radian_per_second, long double>(l); }
 
 
 }  // namespace literals
diff --git a/src/include/units/physical/si/area.h b/src/include/units/physical/si/area.h
index 5b11d402..d66a0d36 100644
--- a/src/include/units/physical/si/area.h
+++ b/src/include/units/physical/si/area.h
@@ -60,92 +60,92 @@ using area = quantity<dim_area, U, Rep>;
 inline namespace literals {
 
 // m2
-constexpr auto operator"" q_m2(unsigned long long l) { return area<square_metre, std::int64_t>(l); }
-constexpr auto operator"" q_m2(long double l) { return area<square_metre, long double>(l); }
+constexpr auto operator"" _q_m2(unsigned long long l) { return area<square_metre, std::int64_t>(l); }
+constexpr auto operator"" _q_m2(long double l) { return area<square_metre, long double>(l); }
 
 // ym2
-constexpr auto operator"" q_ym2(unsigned long long l) { return area<square_yoctometre, std::int64_t>(l); }
-constexpr auto operator"" q_ym2(long double l) { return area<square_yoctometre, long double>(l); }
+constexpr auto operator"" _q_ym2(unsigned long long l) { return area<square_yoctometre, std::int64_t>(l); }
+constexpr auto operator"" _q_ym2(long double l) { return area<square_yoctometre, long double>(l); }
 
 // zm2
-constexpr auto operator"" q_zm2(unsigned long long l) { return area<square_zeptometre, std::int64_t>(l); }
-constexpr auto operator"" q_zm2(long double l) { return area<square_zeptometre, long double>(l); }
+constexpr auto operator"" _q_zm2(unsigned long long l) { return area<square_zeptometre, std::int64_t>(l); }
+constexpr auto operator"" _q_zm2(long double l) { return area<square_zeptometre, long double>(l); }
 
 // am2
-constexpr auto operator"" q_am2(unsigned long long l) { return area<square_attometre, std::int64_t>(l); }
-constexpr auto operator"" q_am2(long double l) { return area<square_attometre, long double>(l); }
+constexpr auto operator"" _q_am2(unsigned long long l) { return area<square_attometre, std::int64_t>(l); }
+constexpr auto operator"" _q_am2(long double l) { return area<square_attometre, long double>(l); }
 
 // fm2
-constexpr auto operator"" q_fm2(unsigned long long l) { return area<square_femtometre, std::int64_t>(l); }
-constexpr auto operator"" q_fm2(long double l) { return area<square_femtometre, long double>(l); }
+constexpr auto operator"" _q_fm2(unsigned long long l) { return area<square_femtometre, std::int64_t>(l); }
+constexpr auto operator"" _q_fm2(long double l) { return area<square_femtometre, long double>(l); }
 
 // pm2
-constexpr auto operator"" q_pm2(unsigned long long l) { return area<square_picometre, std::int64_t>(l); }
-constexpr auto operator"" q_pm2(long double l) { return area<square_picometre, long double>(l); }
+constexpr auto operator"" _q_pm2(unsigned long long l) { return area<square_picometre, std::int64_t>(l); }
+constexpr auto operator"" _q_pm2(long double l) { return area<square_picometre, long double>(l); }
 
 // nm2
-constexpr auto operator"" q_nm2(unsigned long long l) { return area<square_nanometre, std::int64_t>(l); }
-constexpr auto operator"" q_nm2(long double l) { return area<square_nanometre, long double>(l); }
+constexpr auto operator"" _q_nm2(unsigned long long l) { return area<square_nanometre, std::int64_t>(l); }
+constexpr auto operator"" _q_nm2(long double l) { return area<square_nanometre, long double>(l); }
 
 // um2
-constexpr auto operator"" q_um2(unsigned long long l) { return area<square_micrometre, std::int64_t>(l); }
-constexpr auto operator"" q_um2(long double l) { return area<square_micrometre, long double>(l); }
+constexpr auto operator"" _q_um2(unsigned long long l) { return area<square_micrometre, std::int64_t>(l); }
+constexpr auto operator"" _q_um2(long double l) { return area<square_micrometre, long double>(l); }
 
 // mm2
-constexpr auto operator"" q_mm2(unsigned long long l) { return area<square_millimetre, std::int64_t>(l); }
-constexpr auto operator"" q_mm2(long double l) { return area<square_millimetre, long double>(l); }
+constexpr auto operator"" _q_mm2(unsigned long long l) { return area<square_millimetre, std::int64_t>(l); }
+constexpr auto operator"" _q_mm2(long double l) { return area<square_millimetre, long double>(l); }
 
 // cm2
-constexpr auto operator"" q_cm2(unsigned long long l) { return area<square_centimetre, std::int64_t>(l); }
-constexpr auto operator"" q_cm2(long double l) { return area<square_centimetre, long double>(l); }
+constexpr auto operator"" _q_cm2(unsigned long long l) { return area<square_centimetre, std::int64_t>(l); }
+constexpr auto operator"" _q_cm2(long double l) { return area<square_centimetre, long double>(l); }
 
 // dm2
-constexpr auto operator"" q_dm2(unsigned long long l) { return area<square_decimetre, std::int64_t>(l); }
-constexpr auto operator"" q_dm2(long double l) { return area<square_decimetre, long double>(l); }
+constexpr auto operator"" _q_dm2(unsigned long long l) { return area<square_decimetre, std::int64_t>(l); }
+constexpr auto operator"" _q_dm2(long double l) { return area<square_decimetre, long double>(l); }
 
 // dam2
-constexpr auto operator"" q_dam2(unsigned long long l) { return area<square_decametre, std::int64_t>(l); }
-constexpr auto operator"" q_dam2(long double l) { return area<square_decametre, long double>(l); }
+constexpr auto operator"" _q_dam2(unsigned long long l) { return area<square_decametre, std::int64_t>(l); }
+constexpr auto operator"" _q_dam2(long double l) { return area<square_decametre, long double>(l); }
 
 // hm2
-constexpr auto operator"" q_hm2(unsigned long long l) { return area<square_hectometre, std::int64_t>(l); }
-constexpr auto operator"" q_hm2(long double l) { return area<square_hectometre, long double>(l); }
+constexpr auto operator"" _q_hm2(unsigned long long l) { return area<square_hectometre, std::int64_t>(l); }
+constexpr auto operator"" _q_hm2(long double l) { return area<square_hectometre, long double>(l); }
 
 // km2
-constexpr auto operator"" q_km2(unsigned long long l) { return area<square_kilometre, std::int64_t>(l); }
-constexpr auto operator"" q_km2(long double l) { return area<square_kilometre, long double>(l); }
+constexpr auto operator"" _q_km2(unsigned long long l) { return area<square_kilometre, std::int64_t>(l); }
+constexpr auto operator"" _q_km2(long double l) { return area<square_kilometre, long double>(l); }
 
 // Mm2
-constexpr auto operator"" q_Mm2(unsigned long long l) { return area<square_megametre, std::int64_t>(l); }
-constexpr auto operator"" q_Mm2(long double l) { return area<square_megametre, long double>(l); }
+constexpr auto operator"" _q_Mm2(unsigned long long l) { return area<square_megametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Mm2(long double l) { return area<square_megametre, long double>(l); }
 
 // Gm2
-constexpr auto operator"" q_Gm2(unsigned long long l) { return area<square_gigametre, std::int64_t>(l); }
-constexpr auto operator"" q_Gm2(long double l) { return area<square_gigametre, long double>(l); }
+constexpr auto operator"" _q_Gm2(unsigned long long l) { return area<square_gigametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Gm2(long double l) { return area<square_gigametre, long double>(l); }
 
 // Tm2
-constexpr auto operator"" q_Tm2(unsigned long long l) { return area<square_terametre, std::int64_t>(l); }
-constexpr auto operator"" q_Tm2(long double l) { return area<square_terametre, long double>(l); }
+constexpr auto operator"" _q_Tm2(unsigned long long l) { return area<square_terametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Tm2(long double l) { return area<square_terametre, long double>(l); }
 
 // Pm2
-constexpr auto operator"" q_Pm2(unsigned long long l) { return area<square_petametre, std::int64_t>(l); }
-constexpr auto operator"" q_Pm2(long double l) { return area<square_petametre, long double>(l); }
+constexpr auto operator"" _q_Pm2(unsigned long long l) { return area<square_petametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Pm2(long double l) { return area<square_petametre, long double>(l); }
 
 // Em2
-constexpr auto operator"" q_Em2(unsigned long long l) { return area<square_exametre, std::int64_t>(l); }
-constexpr auto operator"" q_Em2(long double l) { return area<square_exametre, long double>(l); }
+constexpr auto operator"" _q_Em2(unsigned long long l) { return area<square_exametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Em2(long double l) { return area<square_exametre, long double>(l); }
 
 // Zm2
-constexpr auto operator"" q_Zm2(unsigned long long l) { return area<square_zettametre, std::int64_t>(l); }
-constexpr auto operator"" q_Zm2(long double l) { return area<square_zettametre, long double>(l); }
+constexpr auto operator"" _q_Zm2(unsigned long long l) { return area<square_zettametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Zm2(long double l) { return area<square_zettametre, long double>(l); }
 
 // Ym2
-constexpr auto operator"" q_Ym2(unsigned long long l) { return area<square_yottametre, std::int64_t>(l); }
-constexpr auto operator"" q_Ym2(long double l) { return area<square_yottametre, long double>(l); }
+constexpr auto operator"" _q_Ym2(unsigned long long l) { return area<square_yottametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Ym2(long double l) { return area<square_yottametre, long double>(l); }
 
 // ha
-constexpr auto operator"" q_ha(unsigned long long l) { return area<hectare, std::int64_t>(l); }
-constexpr auto operator"" q_ha(long double l) { return area<hectare, long double>(l); }
+constexpr auto operator"" _q_ha(unsigned long long l) { return area<hectare, std::int64_t>(l); }
+constexpr auto operator"" _q_ha(long double l) { return area<hectare, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/capacitance.h b/src/include/units/physical/si/capacitance.h
index 3287b5fc..4ee8437d 100644
--- a/src/include/units/physical/si/capacitance.h
+++ b/src/include/units/physical/si/capacitance.h
@@ -60,88 +60,88 @@ using capacitance = quantity<dim_capacitance, U, Rep>;
 inline namespace literals {
 
 // F
-constexpr auto operator"" q_F(unsigned long long l) { return capacitance<farad, std::int64_t>(l); }
-constexpr auto operator"" q_F(long double l) { return capacitance<farad, long double>(l); }
+constexpr auto operator"" _q_F(unsigned long long l) { return capacitance<farad, std::int64_t>(l); }
+constexpr auto operator"" _q_F(long double l) { return capacitance<farad, long double>(l); }
 
 // yF
-constexpr auto operator"" q_yF(unsigned long long l) { return capacitance<yoctofarad, std::int64_t>(l); }
-constexpr auto operator"" q_yF(long double l) { return capacitance<yoctofarad, long double>(l); }
+constexpr auto operator"" _q_yF(unsigned long long l) { return capacitance<yoctofarad, std::int64_t>(l); }
+constexpr auto operator"" _q_yF(long double l) { return capacitance<yoctofarad, long double>(l); }
 
 // zF
-constexpr auto operator"" q_zF(unsigned long long l) { return capacitance<zeptofarad, std::int64_t>(l); }
-constexpr auto operator"" q_zF(long double l) { return capacitance<zeptofarad, long double>(l); }
+constexpr auto operator"" _q_zF(unsigned long long l) { return capacitance<zeptofarad, std::int64_t>(l); }
+constexpr auto operator"" _q_zF(long double l) { return capacitance<zeptofarad, long double>(l); }
 
 // aF
-constexpr auto operator"" q_aF(unsigned long long l) { return capacitance<attofarad, std::int64_t>(l); }
-constexpr auto operator"" q_aF(long double l) { return capacitance<attofarad, long double>(l); }
+constexpr auto operator"" _q_aF(unsigned long long l) { return capacitance<attofarad, std::int64_t>(l); }
+constexpr auto operator"" _q_aF(long double l) { return capacitance<attofarad, long double>(l); }
 
 // fF
-constexpr auto operator"" q_fF(unsigned long long l) { return capacitance<femtofarad, std::int64_t>(l); }
-constexpr auto operator"" q_fF(long double l) { return capacitance<femtofarad, long double>(l); }
+constexpr auto operator"" _q_fF(unsigned long long l) { return capacitance<femtofarad, std::int64_t>(l); }
+constexpr auto operator"" _q_fF(long double l) { return capacitance<femtofarad, long double>(l); }
 
 // pF
-constexpr auto operator"" q_pF(unsigned long long l) { return capacitance<picofarad, std::int64_t>(l); }
-constexpr auto operator"" q_pF(long double l) { return capacitance<picofarad, long double>(l); }
+constexpr auto operator"" _q_pF(unsigned long long l) { return capacitance<picofarad, std::int64_t>(l); }
+constexpr auto operator"" _q_pF(long double l) { return capacitance<picofarad, long double>(l); }
 
 // nF
-constexpr auto operator"" q_nF(unsigned long long l) { return capacitance<nanofarad, std::int64_t>(l); }
-constexpr auto operator"" q_nF(long double l) { return capacitance<nanofarad, long double>(l); }
+constexpr auto operator"" _q_nF(unsigned long long l) { return capacitance<nanofarad, std::int64_t>(l); }
+constexpr auto operator"" _q_nF(long double l) { return capacitance<nanofarad, long double>(l); }
 
 // uF
-constexpr auto operator"" q_uF(unsigned long long l) { return capacitance<microfarad, std::int64_t>(l); }
-constexpr auto operator"" q_uF(long double l) { return capacitance<microfarad, long double>(l); }
+constexpr auto operator"" _q_uF(unsigned long long l) { return capacitance<microfarad, std::int64_t>(l); }
+constexpr auto operator"" _q_uF(long double l) { return capacitance<microfarad, long double>(l); }
 
 // mF
-constexpr auto operator"" q_mF(unsigned long long l) { return capacitance<millifarad, std::int64_t>(l); }
-constexpr auto operator"" q_mF(long double l) { return capacitance<millifarad, long double>(l); }
+constexpr auto operator"" _q_mF(unsigned long long l) { return capacitance<millifarad, std::int64_t>(l); }
+constexpr auto operator"" _q_mF(long double l) { return capacitance<millifarad, long double>(l); }
 
 // cF
-constexpr auto operator"" q_cF(unsigned long long l) { return capacitance<centifarad, std::int64_t>(l); }
-constexpr auto operator"" q_cF(long double l) { return capacitance<centifarad, long double>(l); }
+constexpr auto operator"" _q_cF(unsigned long long l) { return capacitance<centifarad, std::int64_t>(l); }
+constexpr auto operator"" _q_cF(long double l) { return capacitance<centifarad, long double>(l); }
 
 // dF
-constexpr auto operator"" q_dF(unsigned long long l) { return capacitance<decifarad, std::int64_t>(l); }
-constexpr auto operator"" q_dF(long double l) { return capacitance<decifarad, long double>(l); }
+constexpr auto operator"" _q_dF(unsigned long long l) { return capacitance<decifarad, std::int64_t>(l); }
+constexpr auto operator"" _q_dF(long double l) { return capacitance<decifarad, long double>(l); }
 
 // daF
-constexpr auto operator"" q_daF(unsigned long long l) { return capacitance<decafarad, std::int64_t>(l); }
-constexpr auto operator"" q_daF(long double l) { return capacitance<decafarad, long double>(l); }
+constexpr auto operator"" _q_daF(unsigned long long l) { return capacitance<decafarad, std::int64_t>(l); }
+constexpr auto operator"" _q_daF(long double l) { return capacitance<decafarad, long double>(l); }
 
 // hF
-constexpr auto operator"" q_hF(unsigned long long l) { return capacitance<hectofarad, std::int64_t>(l); }
-constexpr auto operator"" q_hF(long double l) { return capacitance<hectofarad, long double>(l); }
+constexpr auto operator"" _q_hF(unsigned long long l) { return capacitance<hectofarad, std::int64_t>(l); }
+constexpr auto operator"" _q_hF(long double l) { return capacitance<hectofarad, long double>(l); }
 
 // kF
-constexpr auto operator"" q_kF(unsigned long long l) { return capacitance<kilofarad, std::int64_t>(l); }
-constexpr auto operator"" q_kF(long double l) { return capacitance<kilofarad, long double>(l); }
+constexpr auto operator"" _q_kF(unsigned long long l) { return capacitance<kilofarad, std::int64_t>(l); }
+constexpr auto operator"" _q_kF(long double l) { return capacitance<kilofarad, long double>(l); }
 
 // MF
-constexpr auto operator"" q_MF(unsigned long long l) { return capacitance<megafarad, std::int64_t>(l); }
-constexpr auto operator"" q_MF(long double l) { return capacitance<megafarad, long double>(l); }
+constexpr auto operator"" _q_MF(unsigned long long l) { return capacitance<megafarad, std::int64_t>(l); }
+constexpr auto operator"" _q_MF(long double l) { return capacitance<megafarad, long double>(l); }
 
 // GF
-constexpr auto operator"" q_GF(unsigned long long l) { return capacitance<gigafarad, std::int64_t>(l); }
-constexpr auto operator"" q_GF(long double l) { return capacitance<gigafarad, long double>(l); }
+constexpr auto operator"" _q_GF(unsigned long long l) { return capacitance<gigafarad, std::int64_t>(l); }
+constexpr auto operator"" _q_GF(long double l) { return capacitance<gigafarad, long double>(l); }
 
 // TF
-constexpr auto operator"" q_TF(unsigned long long l) { return capacitance<terafarad, std::int64_t>(l); }
-constexpr auto operator"" q_TF(long double l) { return capacitance<terafarad, long double>(l); }
+constexpr auto operator"" _q_TF(unsigned long long l) { return capacitance<terafarad, std::int64_t>(l); }
+constexpr auto operator"" _q_TF(long double l) { return capacitance<terafarad, long double>(l); }
 
 // PF
-constexpr auto operator"" q_PF(unsigned long long l) { return capacitance<petafarad, std::int64_t>(l); }
-constexpr auto operator"" q_PF(long double l) { return capacitance<petafarad, long double>(l); }
+constexpr auto operator"" _q_PF(unsigned long long l) { return capacitance<petafarad, std::int64_t>(l); }
+constexpr auto operator"" _q_PF(long double l) { return capacitance<petafarad, long double>(l); }
 
 // EF
-constexpr auto operator"" q_EF(unsigned long long l) { return capacitance<exafarad, std::int64_t>(l); }
-constexpr auto operator"" q_EF(long double l) { return capacitance<exafarad, long double>(l); }
+constexpr auto operator"" _q_EF(unsigned long long l) { return capacitance<exafarad, std::int64_t>(l); }
+constexpr auto operator"" _q_EF(long double l) { return capacitance<exafarad, long double>(l); }
 
 // ZF
-constexpr auto operator"" q_ZF(unsigned long long l) { return capacitance<zettafarad, std::int64_t>(l); }
-constexpr auto operator"" q_ZF(long double l) { return capacitance<zettafarad, long double>(l); }
+constexpr auto operator"" _q_ZF(unsigned long long l) { return capacitance<zettafarad, std::int64_t>(l); }
+constexpr auto operator"" _q_ZF(long double l) { return capacitance<zettafarad, long double>(l); }
 
 // YF
-constexpr auto operator"" q_YF(unsigned long long l) { return capacitance<yottafarad, std::int64_t>(l); }
-constexpr auto operator"" q_YF(long double l) { return capacitance<yottafarad, long double>(l); }
+constexpr auto operator"" _q_YF(unsigned long long l) { return capacitance<yottafarad, std::int64_t>(l); }
+constexpr auto operator"" _q_YF(long double l) { return capacitance<yottafarad, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/catalytic_activity.h b/src/include/units/physical/si/catalytic_activity.h
index a67e9a64..114712b8 100644
--- a/src/include/units/physical/si/catalytic_activity.h
+++ b/src/include/units/physical/si/catalytic_activity.h
@@ -62,92 +62,92 @@ using catalytic_activity = quantity<dim_catalytic_activity, U, Rep>;
 inline namespace literals {
 
 // kat
-constexpr auto operator"" q_kat(unsigned long long l) { return catalytic_activity<katal, std::int64_t>(l); }
-constexpr auto operator"" q_kat(long double l) { return catalytic_activity<katal, long double>(l); }
+constexpr auto operator"" _q_kat(unsigned long long l) { return catalytic_activity<katal, std::int64_t>(l); }
+constexpr auto operator"" _q_kat(long double l) { return catalytic_activity<katal, long double>(l); }
 
 // ykat
-constexpr auto operator"" q_ykat(unsigned long long l) { return catalytic_activity<yoctokatal, std::int64_t>(l); }
-constexpr auto operator"" q_ykat(long double l) { return catalytic_activity<yoctokatal, long double>(l); }
+constexpr auto operator"" _q_ykat(unsigned long long l) { return catalytic_activity<yoctokatal, std::int64_t>(l); }
+constexpr auto operator"" _q_ykat(long double l) { return catalytic_activity<yoctokatal, long double>(l); }
 
 // zkat
-constexpr auto operator"" q_zkat(unsigned long long l) { return catalytic_activity<zeptokatal, std::int64_t>(l); }
-constexpr auto operator"" q_zkat(long double l) { return catalytic_activity<zeptokatal, long double>(l); }
+constexpr auto operator"" _q_zkat(unsigned long long l) { return catalytic_activity<zeptokatal, std::int64_t>(l); }
+constexpr auto operator"" _q_zkat(long double l) { return catalytic_activity<zeptokatal, long double>(l); }
 
 // akat
-constexpr auto operator"" q_akat(unsigned long long l) { return catalytic_activity<attokatal, std::int64_t>(l); }
-constexpr auto operator"" q_akat(long double l) { return catalytic_activity<attokatal, long double>(l); }
+constexpr auto operator"" _q_akat(unsigned long long l) { return catalytic_activity<attokatal, std::int64_t>(l); }
+constexpr auto operator"" _q_akat(long double l) { return catalytic_activity<attokatal, long double>(l); }
 
 // fkat
-constexpr auto operator"" q_fkat(unsigned long long l) { return catalytic_activity<femtokatal, std::int64_t>(l); }
-constexpr auto operator"" q_fkat(long double l) { return catalytic_activity<femtokatal, long double>(l); }
+constexpr auto operator"" _q_fkat(unsigned long long l) { return catalytic_activity<femtokatal, std::int64_t>(l); }
+constexpr auto operator"" _q_fkat(long double l) { return catalytic_activity<femtokatal, long double>(l); }
 
 // pkat
-constexpr auto operator"" q_pkat(unsigned long long l) { return catalytic_activity<picokatal, std::int64_t>(l); }
-constexpr auto operator"" q_pkat(long double l) { return catalytic_activity<picokatal, long double>(l); }
+constexpr auto operator"" _q_pkat(unsigned long long l) { return catalytic_activity<picokatal, std::int64_t>(l); }
+constexpr auto operator"" _q_pkat(long double l) { return catalytic_activity<picokatal, long double>(l); }
 
 // nkat
-constexpr auto operator"" q_nkat(unsigned long long l) { return catalytic_activity<nanokatal, std::int64_t>(l); }
-constexpr auto operator"" q_nkat(long double l) { return catalytic_activity<nanokatal, long double>(l); }
+constexpr auto operator"" _q_nkat(unsigned long long l) { return catalytic_activity<nanokatal, std::int64_t>(l); }
+constexpr auto operator"" _q_nkat(long double l) { return catalytic_activity<nanokatal, long double>(l); }
 
 // ukat
-constexpr auto operator"" q_ukat(unsigned long long l) { return catalytic_activity<microkatal, std::int64_t>(l); }
-constexpr auto operator"" q_ukat(long double l) { return catalytic_activity<microkatal, long double>(l); }
+constexpr auto operator"" _q_ukat(unsigned long long l) { return catalytic_activity<microkatal, std::int64_t>(l); }
+constexpr auto operator"" _q_ukat(long double l) { return catalytic_activity<microkatal, long double>(l); }
 
 // mkat
-constexpr auto operator"" q_mkat(unsigned long long l) { return catalytic_activity<millikatal, std::int64_t>(l); }
-constexpr auto operator"" q_mkat(long double l) { return catalytic_activity<millikatal, long double>(l); }
+constexpr auto operator"" _q_mkat(unsigned long long l) { return catalytic_activity<millikatal, std::int64_t>(l); }
+constexpr auto operator"" _q_mkat(long double l) { return catalytic_activity<millikatal, long double>(l); }
 
 // ckat
-constexpr auto operator"" q_ckat(unsigned long long l) { return catalytic_activity<centikatal, std::int64_t>(l); }
-constexpr auto operator"" q_ckat(long double l) { return catalytic_activity<centikatal, long double>(l); }
+constexpr auto operator"" _q_ckat(unsigned long long l) { return catalytic_activity<centikatal, std::int64_t>(l); }
+constexpr auto operator"" _q_ckat(long double l) { return catalytic_activity<centikatal, long double>(l); }
 
 // dkat
-constexpr auto operator"" q_dkat(unsigned long long l) { return catalytic_activity<decikatal, std::int64_t>(l); }
-constexpr auto operator"" q_dkat(long double l) { return catalytic_activity<decikatal, long double>(l); }
+constexpr auto operator"" _q_dkat(unsigned long long l) { return catalytic_activity<decikatal, std::int64_t>(l); }
+constexpr auto operator"" _q_dkat(long double l) { return catalytic_activity<decikatal, long double>(l); }
 
 // dakat
-constexpr auto operator"" q_dakat(unsigned long long l) { return catalytic_activity<decakatal, std::int64_t>(l); }
-constexpr auto operator"" q_dakat(long double l) { return catalytic_activity<decakatal, long double>(l); }
+constexpr auto operator"" _q_dakat(unsigned long long l) { return catalytic_activity<decakatal, std::int64_t>(l); }
+constexpr auto operator"" _q_dakat(long double l) { return catalytic_activity<decakatal, long double>(l); }
 
 // hkat
-constexpr auto operator"" q_hkat(unsigned long long l) { return catalytic_activity<hectokatal, std::int64_t>(l); }
-constexpr auto operator"" q_hkat(long double l) { return catalytic_activity<hectokatal, long double>(l); }
+constexpr auto operator"" _q_hkat(unsigned long long l) { return catalytic_activity<hectokatal, std::int64_t>(l); }
+constexpr auto operator"" _q_hkat(long double l) { return catalytic_activity<hectokatal, long double>(l); }
 
 // kkat
-constexpr auto operator"" q_kkat(unsigned long long l) { return catalytic_activity<kilokatal, std::int64_t>(l); }
-constexpr auto operator"" q_kkat(long double l) { return catalytic_activity<kilokatal, long double>(l); }
+constexpr auto operator"" _q_kkat(unsigned long long l) { return catalytic_activity<kilokatal, std::int64_t>(l); }
+constexpr auto operator"" _q_kkat(long double l) { return catalytic_activity<kilokatal, long double>(l); }
 
 // Mkat
-constexpr auto operator"" q_Mkat(unsigned long long l) { return catalytic_activity<megakatal, std::int64_t>(l); }
-constexpr auto operator"" q_Mkat(long double l) { return catalytic_activity<megakatal, long double>(l); }
+constexpr auto operator"" _q_Mkat(unsigned long long l) { return catalytic_activity<megakatal, std::int64_t>(l); }
+constexpr auto operator"" _q_Mkat(long double l) { return catalytic_activity<megakatal, long double>(l); }
 
 // Gkat
-constexpr auto operator"" q_Gkat(unsigned long long l) { return catalytic_activity<gigakatal, std::int64_t>(l); }
-constexpr auto operator"" q_Gkat(long double l) { return catalytic_activity<gigakatal, long double>(l); }
+constexpr auto operator"" _q_Gkat(unsigned long long l) { return catalytic_activity<gigakatal, std::int64_t>(l); }
+constexpr auto operator"" _q_Gkat(long double l) { return catalytic_activity<gigakatal, long double>(l); }
 
 // Tkat
-constexpr auto operator"" q_Tkat(unsigned long long l) { return catalytic_activity<terakatal, std::int64_t>(l); }
-constexpr auto operator"" q_Tkat(long double l) { return catalytic_activity<terakatal, long double>(l); }
+constexpr auto operator"" _q_Tkat(unsigned long long l) { return catalytic_activity<terakatal, std::int64_t>(l); }
+constexpr auto operator"" _q_Tkat(long double l) { return catalytic_activity<terakatal, long double>(l); }
 
 // Pkat
-constexpr auto operator"" q_Pkat(unsigned long long l) { return catalytic_activity<petakatal, std::int64_t>(l); }
-constexpr auto operator"" q_Pkat(long double l) { return catalytic_activity<petakatal, long double>(l); }
+constexpr auto operator"" _q_Pkat(unsigned long long l) { return catalytic_activity<petakatal, std::int64_t>(l); }
+constexpr auto operator"" _q_Pkat(long double l) { return catalytic_activity<petakatal, long double>(l); }
 
 // Ekat
-constexpr auto operator"" q_Ekat(unsigned long long l) { return catalytic_activity<exakatal, std::int64_t>(l); }
-constexpr auto operator"" q_Ekat(long double l) { return catalytic_activity<exakatal, long double>(l); }
+constexpr auto operator"" _q_Ekat(unsigned long long l) { return catalytic_activity<exakatal, std::int64_t>(l); }
+constexpr auto operator"" _q_Ekat(long double l) { return catalytic_activity<exakatal, long double>(l); }
 
 // Zkat
-constexpr auto operator"" q_Zkat(unsigned long long l) { return catalytic_activity<zettakatal, std::int64_t>(l); }
-constexpr auto operator"" q_Zkat(long double l) { return catalytic_activity<zettakatal, long double>(l); }
+constexpr auto operator"" _q_Zkat(unsigned long long l) { return catalytic_activity<zettakatal, std::int64_t>(l); }
+constexpr auto operator"" _q_Zkat(long double l) { return catalytic_activity<zettakatal, long double>(l); }
 
 // Ykat
-constexpr auto operator"" q_Ykat(unsigned long long l) { return catalytic_activity<yottakatal, std::int64_t>(l); }
-constexpr auto operator"" q_Ykat(long double l) { return catalytic_activity<yottakatal, long double>(l); }
+constexpr auto operator"" _q_Ykat(unsigned long long l) { return catalytic_activity<yottakatal, std::int64_t>(l); }
+constexpr auto operator"" _q_Ykat(long double l) { return catalytic_activity<yottakatal, long double>(l); }
 
 // U
-constexpr auto operator"" q_U(unsigned long long l) { return catalytic_activity<enzyme_unit, std::int64_t>(l); }
-constexpr auto operator"" q_U(long double l) { return catalytic_activity<enzyme_unit, long double>(l); }
+constexpr auto operator"" _q_U(unsigned long long l) { return catalytic_activity<enzyme_unit, std::int64_t>(l); }
+constexpr auto operator"" _q_U(long double l) { return catalytic_activity<enzyme_unit, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/charge_density.h b/src/include/units/physical/si/charge_density.h
index 0ccad25a..d63633d9 100644
--- a/src/include/units/physical/si/charge_density.h
+++ b/src/include/units/physical/si/charge_density.h
@@ -45,12 +45,12 @@ using surface_charge_density = quantity<dim_surface_charge_density, U, Rep>;
 inline namespace literals {
 
 // C/m³
-constexpr auto operator"" q_C_per_m3(unsigned long long l) { return charge_density<coulomb_per_metre_cub, std::int64_t>(l); }
-constexpr auto operator"" q_C_per_m3(long double l) { return charge_density<coulomb_per_metre_cub, long double>(l); }
+constexpr auto operator"" _q_C_per_m3(unsigned long long l) { return charge_density<coulomb_per_metre_cub, std::int64_t>(l); }
+constexpr auto operator"" _q_C_per_m3(long double l) { return charge_density<coulomb_per_metre_cub, long double>(l); }
 
 // C/m²
-constexpr auto operator"" q_C_per_m2(unsigned long long l) { return surface_charge_density<coulomb_per_metre_sq, std::int64_t>(l); }
-constexpr auto operator"" q_C_per_m2(long double l) { return surface_charge_density<coulomb_per_metre_sq, long double>(l); }
+constexpr auto operator"" _q_C_per_m2(unsigned long long l) { return surface_charge_density<coulomb_per_metre_sq, std::int64_t>(l); }
+constexpr auto operator"" _q_C_per_m2(long double l) { return surface_charge_density<coulomb_per_metre_sq, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/concentration.h b/src/include/units/physical/si/concentration.h
index 8e85b20c..a2d5c0b0 100644
--- a/src/include/units/physical/si/concentration.h
+++ b/src/include/units/physical/si/concentration.h
@@ -38,8 +38,8 @@ using concentration = quantity<dim_concentration, U, Rep>;
 inline namespace literals {
 
 // mol/m³
-constexpr auto operator"" q_mol_per_m3(unsigned long long l) { return concentration<mol_per_metre_cub, std::int64_t>(l); }
-constexpr auto operator"" q_mol_per_m3(long double l) { return concentration<mol_per_metre_cub, long double>(l); }
+constexpr auto operator"" _q_mol_per_m3(unsigned long long l) { return concentration<mol_per_metre_cub, std::int64_t>(l); }
+constexpr auto operator"" _q_mol_per_m3(long double l) { return concentration<mol_per_metre_cub, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/conductance.h b/src/include/units/physical/si/conductance.h
index b793d54e..49206d0d 100644
--- a/src/include/units/physical/si/conductance.h
+++ b/src/include/units/physical/si/conductance.h
@@ -55,72 +55,72 @@ using conductance = quantity<dim_conductance, U, Rep>;
 inline namespace literals {
 
 // R
-constexpr auto operator"" q_S(unsigned long long l) { return conductance<siemens, std::int64_t>(l); }
-constexpr auto operator"" q_S(long double l) { return conductance<siemens, long double>(l); }
+constexpr auto operator"" _q_S(unsigned long long l) { return conductance<siemens, std::int64_t>(l); }
+constexpr auto operator"" _q_S(long double l) { return conductance<siemens, long double>(l); }
 
 // yS
-constexpr auto operator"" q_yS(unsigned long long l) { return conductance<yoctosiemens, std::int64_t>(l); }
-constexpr auto operator"" q_yS(long double l) { return conductance<yoctosiemens, long double>(l); }
+constexpr auto operator"" _q_yS(unsigned long long l) { return conductance<yoctosiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_yS(long double l) { return conductance<yoctosiemens, long double>(l); }
 
 // zS
-constexpr auto operator"" q_zS(unsigned long long l) { return conductance<zeptosiemens, std::int64_t>(l); }
-constexpr auto operator"" q_zS(long double l) { return conductance<zeptosiemens, long double>(l); }
+constexpr auto operator"" _q_zS(unsigned long long l) { return conductance<zeptosiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_zS(long double l) { return conductance<zeptosiemens, long double>(l); }
 
 // aS
-constexpr auto operator"" q_aS(unsigned long long l) { return conductance<attosiemens, std::int64_t>(l); }
-constexpr auto operator"" q_aS(long double l) { return conductance<attosiemens, long double>(l); }
+constexpr auto operator"" _q_aS(unsigned long long l) { return conductance<attosiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_aS(long double l) { return conductance<attosiemens, long double>(l); }
 
 // fS
-constexpr auto operator"" q_fS(unsigned long long l) { return conductance<femtosiemens, std::int64_t>(l); }
-constexpr auto operator"" q_fS(long double l) { return conductance<femtosiemens, long double>(l); }
+constexpr auto operator"" _q_fS(unsigned long long l) { return conductance<femtosiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_fS(long double l) { return conductance<femtosiemens, long double>(l); }
 
 // pS
-constexpr auto operator"" q_pS(unsigned long long l) { return conductance<picosiemens, std::int64_t>(l); }
-constexpr auto operator"" q_pS(long double l) { return conductance<picosiemens, long double>(l); }
+constexpr auto operator"" _q_pS(unsigned long long l) { return conductance<picosiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_pS(long double l) { return conductance<picosiemens, long double>(l); }
 
 // nS
-constexpr auto operator"" q_nS(unsigned long long l) { return conductance<nanosiemens, std::int64_t>(l); }
-constexpr auto operator"" q_nS(long double l) { return conductance<nanosiemens, long double>(l); }
+constexpr auto operator"" _q_nS(unsigned long long l) { return conductance<nanosiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_nS(long double l) { return conductance<nanosiemens, long double>(l); }
 
 // µS
-constexpr auto operator"" q_uS(unsigned long long l) { return conductance<microsiemens, std::int64_t>(l); }
-constexpr auto operator"" q_uS(long double l) { return conductance<microsiemens, long double>(l); }
+constexpr auto operator"" _q_uS(unsigned long long l) { return conductance<microsiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_uS(long double l) { return conductance<microsiemens, long double>(l); }
 
 // mS
-constexpr auto operator"" q_mS(unsigned long long l) { return conductance<millisiemens, std::int64_t>(l); }
-constexpr auto operator"" q_mS(long double l) { return conductance<millisiemens, long double>(l); }
+constexpr auto operator"" _q_mS(unsigned long long l) { return conductance<millisiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_mS(long double l) { return conductance<millisiemens, long double>(l); }
 
 // kS
-constexpr auto operator"" q_kS(unsigned long long l) { return conductance<kilosiemens, std::int64_t>(l); }
-constexpr auto operator"" q_kS(long double l) { return conductance<kilosiemens, long double>(l); }
+constexpr auto operator"" _q_kS(unsigned long long l) { return conductance<kilosiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_kS(long double l) { return conductance<kilosiemens, long double>(l); }
 
 // MS
-constexpr auto operator"" q_MS(unsigned long long l) { return conductance<megasiemens, std::int64_t>(l); }
-constexpr auto operator"" q_MS(long double l) { return conductance<megasiemens, long double>(l); }
+constexpr auto operator"" _q_MS(unsigned long long l) { return conductance<megasiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_MS(long double l) { return conductance<megasiemens, long double>(l); }
 
 // GS
-constexpr auto operator"" q_GS(unsigned long long l) { return conductance<gigasiemens, std::int64_t>(l); }
-constexpr auto operator"" q_GS(long double l) { return conductance<gigasiemens, long double>(l); }
+constexpr auto operator"" _q_GS(unsigned long long l) { return conductance<gigasiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_GS(long double l) { return conductance<gigasiemens, long double>(l); }
 
 // TS
-constexpr auto operator"" q_TS(unsigned long long l) { return conductance<terasiemens, std::int64_t>(l); }
-constexpr auto operator"" q_TS(long double l) { return conductance<terasiemens, long double>(l); }
+constexpr auto operator"" _q_TS(unsigned long long l) { return conductance<terasiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_TS(long double l) { return conductance<terasiemens, long double>(l); }
 
 // PS
-constexpr auto operator"" q_PS(unsigned long long l) { return conductance<petasiemens, std::int64_t>(l); }
-constexpr auto operator"" q_PS(long double l) { return conductance<petasiemens, long double>(l); }
+constexpr auto operator"" _q_PS(unsigned long long l) { return conductance<petasiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_PS(long double l) { return conductance<petasiemens, long double>(l); }
 
 // ES
-constexpr auto operator"" q_ES(unsigned long long l) { return conductance<exasiemens, std::int64_t>(l); }
-constexpr auto operator"" q_ES(long double l) { return conductance<exasiemens, long double>(l); }
+constexpr auto operator"" _q_ES(unsigned long long l) { return conductance<exasiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_ES(long double l) { return conductance<exasiemens, long double>(l); }
 
 // ZS
-constexpr auto operator"" q_ZS(unsigned long long l) { return conductance<zettasiemens, std::int64_t>(l); }
-constexpr auto operator"" q_ZS(long double l) { return conductance<zettasiemens, long double>(l); }
+constexpr auto operator"" _q_ZS(unsigned long long l) { return conductance<zettasiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_ZS(long double l) { return conductance<zettasiemens, long double>(l); }
 
 // YS
-constexpr auto operator"" q_YS(unsigned long long l) { return conductance<yottasiemens, std::int64_t>(l); }
-constexpr auto operator"" q_YS(long double l) { return conductance<yottasiemens, long double>(l); }
+constexpr auto operator"" _q_YS(unsigned long long l) { return conductance<yottasiemens, std::int64_t>(l); }
+constexpr auto operator"" _q_YS(long double l) { return conductance<yottasiemens, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/constants.h b/src/include/units/physical/si/constants.h
index 2a0e0dc0..ad519ce0 100644
--- a/src/include/units/physical/si/constants.h
+++ b/src/include/units/physical/si/constants.h
@@ -54,7 +54,7 @@ template<ScalableNumber Rep = double>
 inline constexpr auto hyperfine_structure_transition_frequency = frequency<hertz, Rep>(9'192'631'770);
 
 // template<ScalableNumber Rep = double>
-// inline constexpr auto luminous_efficacy = 683q_lm / 1q_W;
+// inline constexpr auto luminous_efficacy = 683_q_lm / 1_q_W;
 
 template<ScalableNumber Rep = double>
 inline constexpr auto standard_gravity = acceleration<metre_per_second_sq, Rep>(9.80665);
diff --git a/src/include/units/physical/si/current.h b/src/include/units/physical/si/current.h
index 88e37efd..af808511 100644
--- a/src/include/units/physical/si/current.h
+++ b/src/include/units/physical/si/current.h
@@ -58,88 +58,88 @@ using current = quantity<dim_electric_current, U, Rep>;
 inline namespace literals {
 
 // A
-constexpr auto operator"" q_A(unsigned long long l) { return current<ampere, std::int64_t>(l); }
-constexpr auto operator"" q_A(long double l) { return current<ampere, long double>(l); }
+constexpr auto operator"" _q_A(unsigned long long l) { return current<ampere, std::int64_t>(l); }
+constexpr auto operator"" _q_A(long double l) { return current<ampere, long double>(l); }
 
 // yA
-constexpr auto operator"" q_yA(unsigned long long l) { return current<yoctoampere, std::int64_t>(l); }
-constexpr auto operator"" q_yA(long double l) { return current<yoctoampere, long double>(l); }
+constexpr auto operator"" _q_yA(unsigned long long l) { return current<yoctoampere, std::int64_t>(l); }
+constexpr auto operator"" _q_yA(long double l) { return current<yoctoampere, long double>(l); }
 
 // zA
-constexpr auto operator"" q_zA(unsigned long long l) { return current<zeptoampere, std::int64_t>(l); }
-constexpr auto operator"" q_zA(long double l) { return current<zeptoampere, long double>(l); }
+constexpr auto operator"" _q_zA(unsigned long long l) { return current<zeptoampere, std::int64_t>(l); }
+constexpr auto operator"" _q_zA(long double l) { return current<zeptoampere, long double>(l); }
 
 // aA
-constexpr auto operator"" q_aA(unsigned long long l) { return current<attoampere, std::int64_t>(l); }
-constexpr auto operator"" q_aA(long double l) { return current<attoampere, long double>(l); }
+constexpr auto operator"" _q_aA(unsigned long long l) { return current<attoampere, std::int64_t>(l); }
+constexpr auto operator"" _q_aA(long double l) { return current<attoampere, long double>(l); }
 
 // fA
-constexpr auto operator"" q_fA(unsigned long long l) { return current<femtoampere, std::int64_t>(l); }
-constexpr auto operator"" q_fA(long double l) { return current<femtoampere, long double>(l); }
+constexpr auto operator"" _q_fA(unsigned long long l) { return current<femtoampere, std::int64_t>(l); }
+constexpr auto operator"" _q_fA(long double l) { return current<femtoampere, long double>(l); }
 
 // pA
-constexpr auto operator"" q_pA(unsigned long long l) { return current<picoampere, std::int64_t>(l); }
-constexpr auto operator"" q_pA(long double l) { return current<picoampere, long double>(l); }
+constexpr auto operator"" _q_pA(unsigned long long l) { return current<picoampere, std::int64_t>(l); }
+constexpr auto operator"" _q_pA(long double l) { return current<picoampere, long double>(l); }
 
 // nA
-constexpr auto operator"" q_nA(unsigned long long l) { return current<nanoampere, std::int64_t>(l); }
-constexpr auto operator"" q_nA(long double l) { return current<nanoampere, long double>(l); }
+constexpr auto operator"" _q_nA(unsigned long long l) { return current<nanoampere, std::int64_t>(l); }
+constexpr auto operator"" _q_nA(long double l) { return current<nanoampere, long double>(l); }
 
 // uA
-constexpr auto operator"" q_uA(unsigned long long l) { return current<microampere, std::int64_t>(l); }
-constexpr auto operator"" q_uA(long double l) { return current<microampere, long double>(l); }
+constexpr auto operator"" _q_uA(unsigned long long l) { return current<microampere, std::int64_t>(l); }
+constexpr auto operator"" _q_uA(long double l) { return current<microampere, long double>(l); }
 
 // mA
-constexpr auto operator"" q_mA(unsigned long long l) { return current<milliampere, std::int64_t>(l); }
-constexpr auto operator"" q_mA(long double l) { return current<milliampere, long double>(l); }
+constexpr auto operator"" _q_mA(unsigned long long l) { return current<milliampere, std::int64_t>(l); }
+constexpr auto operator"" _q_mA(long double l) { return current<milliampere, long double>(l); }
 
 // cA
-constexpr auto operator"" q_cA(unsigned long long l) { return current<centiampere, std::int64_t>(l); }
-constexpr auto operator"" q_cA(long double l) { return current<centiampere, long double>(l); }
+constexpr auto operator"" _q_cA(unsigned long long l) { return current<centiampere, std::int64_t>(l); }
+constexpr auto operator"" _q_cA(long double l) { return current<centiampere, long double>(l); }
 
 // dA
-constexpr auto operator"" q_dA(unsigned long long l) { return current<deciampere, std::int64_t>(l); }
-constexpr auto operator"" q_dA(long double l) { return current<deciampere, long double>(l); }
+constexpr auto operator"" _q_dA(unsigned long long l) { return current<deciampere, std::int64_t>(l); }
+constexpr auto operator"" _q_dA(long double l) { return current<deciampere, long double>(l); }
 
 // daA
-constexpr auto operator"" q_daA(unsigned long long l) { return current<decaampere, std::int64_t>(l); }
-constexpr auto operator"" q_daA(long double l) { return current<decaampere, long double>(l); }
+constexpr auto operator"" _q_daA(unsigned long long l) { return current<decaampere, std::int64_t>(l); }
+constexpr auto operator"" _q_daA(long double l) { return current<decaampere, long double>(l); }
 
 // hA
-constexpr auto operator"" q_hA(unsigned long long l) { return current<hectoampere, std::int64_t>(l); }
-constexpr auto operator"" q_hA(long double l) { return current<hectoampere, long double>(l); }
+constexpr auto operator"" _q_hA(unsigned long long l) { return current<hectoampere, std::int64_t>(l); }
+constexpr auto operator"" _q_hA(long double l) { return current<hectoampere, long double>(l); }
 
 // kA
-constexpr auto operator"" q_kA(unsigned long long l) { return current<kiloampere, std::int64_t>(l); }
-constexpr auto operator"" q_kA(long double l) { return current<kiloampere, long double>(l); }
+constexpr auto operator"" _q_kA(unsigned long long l) { return current<kiloampere, std::int64_t>(l); }
+constexpr auto operator"" _q_kA(long double l) { return current<kiloampere, long double>(l); }
 
 // MA
-constexpr auto operator"" q_MA(unsigned long long l) { return current<megaampere, std::int64_t>(l); }
-constexpr auto operator"" q_MA(long double l) { return current<megaampere, long double>(l); }
+constexpr auto operator"" _q_MA(unsigned long long l) { return current<megaampere, std::int64_t>(l); }
+constexpr auto operator"" _q_MA(long double l) { return current<megaampere, long double>(l); }
 
 // GA
-constexpr auto operator"" q_GA(unsigned long long l) { return current<gigaampere, std::int64_t>(l); }
-constexpr auto operator"" q_GA(long double l) { return current<gigaampere, long double>(l); }
+constexpr auto operator"" _q_GA(unsigned long long l) { return current<gigaampere, std::int64_t>(l); }
+constexpr auto operator"" _q_GA(long double l) { return current<gigaampere, long double>(l); }
 
 // TA
-constexpr auto operator"" q_TA(unsigned long long l) { return current<teraampere, std::int64_t>(l); }
-constexpr auto operator"" q_TA(long double l) { return current<teraampere, long double>(l); }
+constexpr auto operator"" _q_TA(unsigned long long l) { return current<teraampere, std::int64_t>(l); }
+constexpr auto operator"" _q_TA(long double l) { return current<teraampere, long double>(l); }
 
 // PA
-constexpr auto operator"" q_PA(unsigned long long l) { return current<petaampere, std::int64_t>(l); }
-constexpr auto operator"" q_PA(long double l) { return current<petaampere, long double>(l); }
+constexpr auto operator"" _q_PA(unsigned long long l) { return current<petaampere, std::int64_t>(l); }
+constexpr auto operator"" _q_PA(long double l) { return current<petaampere, long double>(l); }
 
 // EA
-constexpr auto operator"" q_EA(unsigned long long l) { return current<exaampere, std::int64_t>(l); }
-constexpr auto operator"" q_EA(long double l) { return current<exaampere, long double>(l); }
+constexpr auto operator"" _q_EA(unsigned long long l) { return current<exaampere, std::int64_t>(l); }
+constexpr auto operator"" _q_EA(long double l) { return current<exaampere, long double>(l); }
 
 // ZA
-constexpr auto operator"" q_ZA(unsigned long long l) { return current<zettaampere, std::int64_t>(l); }
-constexpr auto operator"" q_ZA(long double l) { return current<zettaampere, long double>(l); }
+constexpr auto operator"" _q_ZA(unsigned long long l) { return current<zettaampere, std::int64_t>(l); }
+constexpr auto operator"" _q_ZA(long double l) { return current<zettaampere, long double>(l); }
 
 // YA
-constexpr auto operator"" q_YA(unsigned long long l) { return current<yottaampere, std::int64_t>(l); }
-constexpr auto operator"" q_YA(long double l) { return current<yottaampere, long double>(l); }
+constexpr auto operator"" _q_YA(unsigned long long l) { return current<yottaampere, std::int64_t>(l); }
+constexpr auto operator"" _q_YA(long double l) { return current<yottaampere, long double>(l); }
 
 } // namespace literals
 
diff --git a/src/include/units/physical/si/current_density.h b/src/include/units/physical/si/current_density.h
index 19fed28c..bf7fed31 100644
--- a/src/include/units/physical/si/current_density.h
+++ b/src/include/units/physical/si/current_density.h
@@ -39,8 +39,8 @@ using current_density = quantity<dim_current_density, U, Rep>;
 
 inline namespace literals {
 
-constexpr auto operator"" q_A_per_m2(unsigned long long l) { return current_density<ampere_per_metre_sq, std::int64_t>(l); }
-constexpr auto operator"" q_A_per_m2(long double l) { return current_density<ampere_per_metre_sq, long double>(l); }
+constexpr auto operator"" _q_A_per_m2(unsigned long long l) { return current_density<ampere_per_metre_sq, std::int64_t>(l); }
+constexpr auto operator"" _q_A_per_m2(long double l) { return current_density<ampere_per_metre_sq, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/density.h b/src/include/units/physical/si/density.h
index fa9a1707..340e44a4 100644
--- a/src/include/units/physical/si/density.h
+++ b/src/include/units/physical/si/density.h
@@ -39,8 +39,8 @@ using density = quantity<dim_density, U, Rep>;
 
 inline namespace literals {
 
-constexpr auto operator"" q_kg_per_m3(unsigned long long l) { return density<kilogram_per_metre_cub, std::int64_t>(l); }
-constexpr auto operator"" q_kg_per_m3(long double l) { return density<kilogram_per_metre_cub, long double>(l); }
+constexpr auto operator"" _q_kg_per_m3(unsigned long long l) { return density<kilogram_per_metre_cub, std::int64_t>(l); }
+constexpr auto operator"" _q_kg_per_m3(long double l) { return density<kilogram_per_metre_cub, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/dynamic_viscosity.h b/src/include/units/physical/si/dynamic_viscosity.h
index 1a8b7dbb..95d2b716 100644
--- a/src/include/units/physical/si/dynamic_viscosity.h
+++ b/src/include/units/physical/si/dynamic_viscosity.h
@@ -38,8 +38,8 @@ using dynamic_viscosity = quantity<dim_dynamic_viscosity, U, Rep>;
 inline namespace literals {
 
 // Pa·s
-constexpr auto operator"" q_Pa_s(unsigned long long l) { return dynamic_viscosity<pascal_second, std::int64_t>(l); }
-constexpr auto operator"" q_Pa_s(long double l) { return dynamic_viscosity<pascal_second, long double>(l); }
+constexpr auto operator"" _q_Pa_s(unsigned long long l) { return dynamic_viscosity<pascal_second, std::int64_t>(l); }
+constexpr auto operator"" _q_Pa_s(long double l) { return dynamic_viscosity<pascal_second, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/electric_charge.h b/src/include/units/physical/si/electric_charge.h
index 60020408..19333bb2 100644
--- a/src/include/units/physical/si/electric_charge.h
+++ b/src/include/units/physical/si/electric_charge.h
@@ -39,8 +39,8 @@ using electric_charge = quantity<dim_electric_charge, U, Rep>;
 inline namespace literals {
 
 // C
-constexpr auto operator"" q_C(unsigned long long l) { return electric_charge<coulomb, std::int64_t>(l); }
-constexpr auto operator"" q_C(long double l) { return electric_charge<coulomb, long double>(l); }
+constexpr auto operator"" _q_C(unsigned long long l) { return electric_charge<coulomb, std::int64_t>(l); }
+constexpr auto operator"" _q_C(long double l) { return electric_charge<coulomb, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/electric_field_strength.h b/src/include/units/physical/si/electric_field_strength.h
index 0547d2a3..88126358 100644
--- a/src/include/units/physical/si/electric_field_strength.h
+++ b/src/include/units/physical/si/electric_field_strength.h
@@ -37,8 +37,8 @@ using electric_field_strength = quantity<dim_electric_field_strength, U, Rep>;
 inline namespace literals {
 
 // V/m
-constexpr auto operator"" q_V_per_m(unsigned long long l) { return electric_field_strength<volt_per_metre, std::int64_t>(l); }
-constexpr auto operator"" q_V_per_m(long double l) { return electric_field_strength<volt_per_metre, long double>(l); }
+constexpr auto operator"" _q_V_per_m(unsigned long long l) { return electric_field_strength<volt_per_metre, std::int64_t>(l); }
+constexpr auto operator"" _q_V_per_m(long double l) { return electric_field_strength<volt_per_metre, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/energy.h b/src/include/units/physical/si/energy.h
index d18fcd0e..23b71076 100644
--- a/src/include/units/physical/si/energy.h
+++ b/src/include/units/physical/si/energy.h
@@ -58,80 +58,80 @@ using energy = quantity<dim_energy, U, Rep>;
 inline namespace literals {
 
 // J
-constexpr auto operator"" q_J(unsigned long long l) { return energy<joule, std::int64_t>(l); }
-constexpr auto operator"" q_J(long double l) { return energy<joule, long double>(l); }
+constexpr auto operator"" _q_J(unsigned long long l) { return energy<joule, std::int64_t>(l); }
+constexpr auto operator"" _q_J(long double l) { return energy<joule, long double>(l); }
 
 // yJ
-constexpr auto operator"" q_yJ(unsigned long long l) { return energy<yoctojoule, std::int64_t>(l); }
-constexpr auto operator"" q_yJ(long double l) { return energy<yoctojoule, long double>(l); }
+constexpr auto operator"" _q_yJ(unsigned long long l) { return energy<yoctojoule, std::int64_t>(l); }
+constexpr auto operator"" _q_yJ(long double l) { return energy<yoctojoule, long double>(l); }
 
 // zJ
-constexpr auto operator"" q_zJ(unsigned long long l) { return energy<zeptojoule, std::int64_t>(l); }
-constexpr auto operator"" q_zJ(long double l) { return energy<zeptojoule, long double>(l); }
+constexpr auto operator"" _q_zJ(unsigned long long l) { return energy<zeptojoule, std::int64_t>(l); }
+constexpr auto operator"" _q_zJ(long double l) { return energy<zeptojoule, long double>(l); }
 
 // aJ
-constexpr auto operator"" q_aJ(unsigned long long l) { return energy<attojoule, std::int64_t>(l); }
-constexpr auto operator"" q_aJ(long double l) { return energy<attojoule, long double>(l); }
+constexpr auto operator"" _q_aJ(unsigned long long l) { return energy<attojoule, std::int64_t>(l); }
+constexpr auto operator"" _q_aJ(long double l) { return energy<attojoule, long double>(l); }
 
 // fJ
-constexpr auto operator"" q_fJ(unsigned long long l) { return energy<femtojoule, std::int64_t>(l); }
-constexpr auto operator"" q_fJ(long double l) { return energy<femtojoule, long double>(l); }
+constexpr auto operator"" _q_fJ(unsigned long long l) { return energy<femtojoule, std::int64_t>(l); }
+constexpr auto operator"" _q_fJ(long double l) { return energy<femtojoule, long double>(l); }
 
 // pJ
-constexpr auto operator"" q_pJ(unsigned long long l) { return energy<picojoule, std::int64_t>(l); }
-constexpr auto operator"" q_pJ(long double l) { return energy<picojoule, long double>(l); }
+constexpr auto operator"" _q_pJ(unsigned long long l) { return energy<picojoule, std::int64_t>(l); }
+constexpr auto operator"" _q_pJ(long double l) { return energy<picojoule, long double>(l); }
 
 // nJ
-constexpr auto operator"" q_nJ(unsigned long long l) { return energy<nanojoule, std::int64_t>(l); }
-constexpr auto operator"" q_nJ(long double l) { return energy<nanojoule, long double>(l); }
+constexpr auto operator"" _q_nJ(unsigned long long l) { return energy<nanojoule, std::int64_t>(l); }
+constexpr auto operator"" _q_nJ(long double l) { return energy<nanojoule, long double>(l); }
 
 // uJ
-constexpr auto operator"" q_uJ(unsigned long long l) { return energy<microjoule, std::int64_t>(l); }
-constexpr auto operator"" q_uJ(long double l) { return energy<microjoule, long double>(l); }
+constexpr auto operator"" _q_uJ(unsigned long long l) { return energy<microjoule, std::int64_t>(l); }
+constexpr auto operator"" _q_uJ(long double l) { return energy<microjoule, long double>(l); }
 
 // mJ
-constexpr auto operator"" q_mJ(unsigned long long l) { return energy<millijoule, std::int64_t>(l); }
-constexpr auto operator"" q_mJ(long double l) { return energy<millijoule, long double>(l); }
+constexpr auto operator"" _q_mJ(unsigned long long l) { return energy<millijoule, std::int64_t>(l); }
+constexpr auto operator"" _q_mJ(long double l) { return energy<millijoule, long double>(l); }
 
 // kJ
-constexpr auto operator"" q_kJ(unsigned long long l) { return energy<kilojoule, std::int64_t>(l); }
-constexpr auto operator"" q_kJ(long double l) { return energy<kilojoule, long double>(l); }
+constexpr auto operator"" _q_kJ(unsigned long long l) { return energy<kilojoule, std::int64_t>(l); }
+constexpr auto operator"" _q_kJ(long double l) { return energy<kilojoule, long double>(l); }
 
 // MJ
-constexpr auto operator"" q_MJ(unsigned long long l) { return energy<megajoule, std::int64_t>(l); }
-constexpr auto operator"" q_MJ(long double l) { return energy<megajoule, long double>(l); }
+constexpr auto operator"" _q_MJ(unsigned long long l) { return energy<megajoule, std::int64_t>(l); }
+constexpr auto operator"" _q_MJ(long double l) { return energy<megajoule, long double>(l); }
 
 // GJ
-constexpr auto operator"" q_GJ(unsigned long long l) { return energy<gigajoule, std::int64_t>(l); }
-constexpr auto operator"" q_GJ(long double l) { return energy<gigajoule, long double>(l); }
+constexpr auto operator"" _q_GJ(unsigned long long l) { return energy<gigajoule, std::int64_t>(l); }
+constexpr auto operator"" _q_GJ(long double l) { return energy<gigajoule, long double>(l); }
 
 // TJ
-constexpr auto operator"" q_TJ(unsigned long long l) { return energy<terajoule, std::int64_t>(l); }
-constexpr auto operator"" q_TJ(long double l) { return energy<terajoule, long double>(l); }
+constexpr auto operator"" _q_TJ(unsigned long long l) { return energy<terajoule, std::int64_t>(l); }
+constexpr auto operator"" _q_TJ(long double l) { return energy<terajoule, long double>(l); }
 
 // PJ
-constexpr auto operator"" q_PJ(unsigned long long l) { return energy<petajoule, std::int64_t>(l); }
-constexpr auto operator"" q_PJ(long double l) { return energy<petajoule, long double>(l); }
+constexpr auto operator"" _q_PJ(unsigned long long l) { return energy<petajoule, std::int64_t>(l); }
+constexpr auto operator"" _q_PJ(long double l) { return energy<petajoule, long double>(l); }
 
 // EJ
-constexpr auto operator"" q_EJ(unsigned long long l) { return energy<exajoule, std::int64_t>(l); }
-constexpr auto operator"" q_EJ(long double l) { return energy<exajoule, long double>(l); }
+constexpr auto operator"" _q_EJ(unsigned long long l) { return energy<exajoule, std::int64_t>(l); }
+constexpr auto operator"" _q_EJ(long double l) { return energy<exajoule, long double>(l); }
 
 // ZJ
-constexpr auto operator"" q_ZJ(unsigned long long l) { return energy<zettajoule, std::int64_t>(l); }
-constexpr auto operator"" q_ZJ(long double l) { return energy<zettajoule, long double>(l); }
+constexpr auto operator"" _q_ZJ(unsigned long long l) { return energy<zettajoule, std::int64_t>(l); }
+constexpr auto operator"" _q_ZJ(long double l) { return energy<zettajoule, long double>(l); }
 
 // YJ
-constexpr auto operator"" q_YJ(unsigned long long l) { return energy<yottajoule, std::int64_t>(l); }
-constexpr auto operator"" q_YJ(long double l) { return energy<yottajoule, long double>(l); }
+constexpr auto operator"" _q_YJ(unsigned long long l) { return energy<yottajoule, std::int64_t>(l); }
+constexpr auto operator"" _q_YJ(long double l) { return energy<yottajoule, long double>(l); }
 
 // eV
-constexpr auto operator"" q_eV(unsigned long long l) { return energy<electronvolt, std::int64_t>(l); }
-constexpr auto operator"" q_eV(long double l) { return energy<electronvolt, long double>(l); }
+constexpr auto operator"" _q_eV(unsigned long long l) { return energy<electronvolt, std::int64_t>(l); }
+constexpr auto operator"" _q_eV(long double l) { return energy<electronvolt, long double>(l); }
 
 // GeV
-constexpr auto operator"" q_GeV(unsigned long long l) { return energy<gigaelectronvolt, std::int64_t>(l); }
-constexpr auto operator"" q_GeV(long double l) { return energy<gigaelectronvolt, long double>(l); }
+constexpr auto operator"" _q_GeV(unsigned long long l) { return energy<gigaelectronvolt, std::int64_t>(l); }
+constexpr auto operator"" _q_GeV(long double l) { return energy<gigaelectronvolt, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/force.h b/src/include/units/physical/si/force.h
index ce60ad7c..93c5430f 100644
--- a/src/include/units/physical/si/force.h
+++ b/src/include/units/physical/si/force.h
@@ -60,88 +60,88 @@ using force = quantity<dim_force, U, Rep>;
 inline namespace literals {
 
 // N
-constexpr auto operator"" q_N(unsigned long long l) { return force<newton, std::int64_t>(l); }
-constexpr auto operator"" q_N(long double l) { return force<newton, long double>(l); }
+constexpr auto operator"" _q_N(unsigned long long l) { return force<newton, std::int64_t>(l); }
+constexpr auto operator"" _q_N(long double l) { return force<newton, long double>(l); }
 
 // yN
-constexpr auto operator"" q_yN(unsigned long long l) { return force<yoctonewton, std::int64_t>(l); }
-constexpr auto operator"" q_yN(long double l) { return force<yoctonewton, long double>(l); }
+constexpr auto operator"" _q_yN(unsigned long long l) { return force<yoctonewton, std::int64_t>(l); }
+constexpr auto operator"" _q_yN(long double l) { return force<yoctonewton, long double>(l); }
 
 // zN
-constexpr auto operator"" q_zN(unsigned long long l) { return force<zeptonewton, std::int64_t>(l); }
-constexpr auto operator"" q_zN(long double l) { return force<zeptonewton, long double>(l); }
+constexpr auto operator"" _q_zN(unsigned long long l) { return force<zeptonewton, std::int64_t>(l); }
+constexpr auto operator"" _q_zN(long double l) { return force<zeptonewton, long double>(l); }
 
 // aN
-constexpr auto operator"" q_aN(unsigned long long l) { return force<attonewton, std::int64_t>(l); }
-constexpr auto operator"" q_aN(long double l) { return force<attonewton, long double>(l); }
+constexpr auto operator"" _q_aN(unsigned long long l) { return force<attonewton, std::int64_t>(l); }
+constexpr auto operator"" _q_aN(long double l) { return force<attonewton, long double>(l); }
 
 // fN
-constexpr auto operator"" q_fN(unsigned long long l) { return force<femtonewton, std::int64_t>(l); }
-constexpr auto operator"" q_fN(long double l) { return force<femtonewton, long double>(l); }
+constexpr auto operator"" _q_fN(unsigned long long l) { return force<femtonewton, std::int64_t>(l); }
+constexpr auto operator"" _q_fN(long double l) { return force<femtonewton, long double>(l); }
 
 // pN
-constexpr auto operator"" q_pN(unsigned long long l) { return force<piconewton, std::int64_t>(l); }
-constexpr auto operator"" q_pN(long double l) { return force<piconewton, long double>(l); }
+constexpr auto operator"" _q_pN(unsigned long long l) { return force<piconewton, std::int64_t>(l); }
+constexpr auto operator"" _q_pN(long double l) { return force<piconewton, long double>(l); }
 
 // nN
-constexpr auto operator"" q_nN(unsigned long long l) { return force<nanonewton, std::int64_t>(l); }
-constexpr auto operator"" q_nN(long double l) { return force<nanonewton, long double>(l); }
+constexpr auto operator"" _q_nN(unsigned long long l) { return force<nanonewton, std::int64_t>(l); }
+constexpr auto operator"" _q_nN(long double l) { return force<nanonewton, long double>(l); }
 
 // uN
-constexpr auto operator"" q_uN(unsigned long long l) { return force<micronewton, std::int64_t>(l); }
-constexpr auto operator"" q_uN(long double l) { return force<micronewton, long double>(l); }
+constexpr auto operator"" _q_uN(unsigned long long l) { return force<micronewton, std::int64_t>(l); }
+constexpr auto operator"" _q_uN(long double l) { return force<micronewton, long double>(l); }
 
 // mN
-constexpr auto operator"" q_mN(unsigned long long l) { return force<millinewton, std::int64_t>(l); }
-constexpr auto operator"" q_mN(long double l) { return force<millinewton, long double>(l); }
+constexpr auto operator"" _q_mN(unsigned long long l) { return force<millinewton, std::int64_t>(l); }
+constexpr auto operator"" _q_mN(long double l) { return force<millinewton, long double>(l); }
 
 // cN
-constexpr auto operator"" q_cN(unsigned long long l) { return force<centinewton, std::int64_t>(l); }
-constexpr auto operator"" q_cN(long double l) { return force<centinewton, long double>(l); }
+constexpr auto operator"" _q_cN(unsigned long long l) { return force<centinewton, std::int64_t>(l); }
+constexpr auto operator"" _q_cN(long double l) { return force<centinewton, long double>(l); }
 
 // dN
-constexpr auto operator"" q_dN(unsigned long long l) { return force<decinewton, std::int64_t>(l); }
-constexpr auto operator"" q_dN(long double l) { return force<decinewton, long double>(l); }
+constexpr auto operator"" _q_dN(unsigned long long l) { return force<decinewton, std::int64_t>(l); }
+constexpr auto operator"" _q_dN(long double l) { return force<decinewton, long double>(l); }
 
 // daN
-constexpr auto operator"" q_daN(unsigned long long l) { return force<decanewton, std::int64_t>(l); }
-constexpr auto operator"" q_daN(long double l) { return force<decanewton, long double>(l); }
+constexpr auto operator"" _q_daN(unsigned long long l) { return force<decanewton, std::int64_t>(l); }
+constexpr auto operator"" _q_daN(long double l) { return force<decanewton, long double>(l); }
 
 // hN
-constexpr auto operator"" q_hN(unsigned long long l) { return force<hectonewton, std::int64_t>(l); }
-constexpr auto operator"" q_hN(long double l) { return force<hectonewton, long double>(l); }
+constexpr auto operator"" _q_hN(unsigned long long l) { return force<hectonewton, std::int64_t>(l); }
+constexpr auto operator"" _q_hN(long double l) { return force<hectonewton, long double>(l); }
 
 // kN
-constexpr auto operator"" q_kN(unsigned long long l) { return force<kilonewton, std::int64_t>(l); }
-constexpr auto operator"" q_kN(long double l) { return force<kilonewton, long double>(l); }
+constexpr auto operator"" _q_kN(unsigned long long l) { return force<kilonewton, std::int64_t>(l); }
+constexpr auto operator"" _q_kN(long double l) { return force<kilonewton, long double>(l); }
 
 // MN
-constexpr auto operator"" q_MN(unsigned long long l) { return force<meganewton, std::int64_t>(l); }
-constexpr auto operator"" q_MN(long double l) { return force<meganewton, long double>(l); }
+constexpr auto operator"" _q_MN(unsigned long long l) { return force<meganewton, std::int64_t>(l); }
+constexpr auto operator"" _q_MN(long double l) { return force<meganewton, long double>(l); }
 
 // GN
-constexpr auto operator"" q_GN(unsigned long long l) { return force<giganewton, std::int64_t>(l); }
-constexpr auto operator"" q_GN(long double l) { return force<giganewton, long double>(l); }
+constexpr auto operator"" _q_GN(unsigned long long l) { return force<giganewton, std::int64_t>(l); }
+constexpr auto operator"" _q_GN(long double l) { return force<giganewton, long double>(l); }
 
 // TN
-constexpr auto operator"" q_TN(unsigned long long l) { return force<teranewton, std::int64_t>(l); }
-constexpr auto operator"" q_TN(long double l) { return force<teranewton, long double>(l); }
+constexpr auto operator"" _q_TN(unsigned long long l) { return force<teranewton, std::int64_t>(l); }
+constexpr auto operator"" _q_TN(long double l) { return force<teranewton, long double>(l); }
 
 // PN
-constexpr auto operator"" q_PN(unsigned long long l) { return force<petanewton, std::int64_t>(l); }
-constexpr auto operator"" q_PN(long double l) { return force<petanewton, long double>(l); }
+constexpr auto operator"" _q_PN(unsigned long long l) { return force<petanewton, std::int64_t>(l); }
+constexpr auto operator"" _q_PN(long double l) { return force<petanewton, long double>(l); }
 
 // EN
-constexpr auto operator"" q_EN(unsigned long long l) { return force<exanewton, std::int64_t>(l); }
-constexpr auto operator"" q_EN(long double l) { return force<exanewton, long double>(l); }
+constexpr auto operator"" _q_EN(unsigned long long l) { return force<exanewton, std::int64_t>(l); }
+constexpr auto operator"" _q_EN(long double l) { return force<exanewton, long double>(l); }
 
 // ZN
-constexpr auto operator"" q_ZN(unsigned long long l) { return force<zettanewton, std::int64_t>(l); }
-constexpr auto operator"" q_ZN(long double l) { return force<zettanewton, long double>(l); }
+constexpr auto operator"" _q_ZN(unsigned long long l) { return force<zettanewton, std::int64_t>(l); }
+constexpr auto operator"" _q_ZN(long double l) { return force<zettanewton, long double>(l); }
 
 // YN
-constexpr auto operator"" q_YN(unsigned long long l) { return force<yottanewton, std::int64_t>(l); }
-constexpr auto operator"" q_YN(long double l) { return force<yottanewton, long double>(l); }
+constexpr auto operator"" _q_YN(unsigned long long l) { return force<yottanewton, std::int64_t>(l); }
+constexpr auto operator"" _q_YN(long double l) { return force<yottanewton, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/frequency.h b/src/include/units/physical/si/frequency.h
index b41f4e46..b737089a 100644
--- a/src/include/units/physical/si/frequency.h
+++ b/src/include/units/physical/si/frequency.h
@@ -54,72 +54,72 @@ using frequency = quantity<dim_frequency, U, Rep>;
 inline namespace literals {
 
 // Hz
-constexpr auto operator"" q_Hz(unsigned long long l) { return frequency<hertz, std::int64_t>(l); }
-constexpr auto operator"" q_Hz(long double l) { return frequency<hertz, long double>(l); }
+constexpr auto operator"" _q_Hz(unsigned long long l) { return frequency<hertz, std::int64_t>(l); }
+constexpr auto operator"" _q_Hz(long double l) { return frequency<hertz, long double>(l); }
 
 // yHz
-constexpr auto operator"" q_yHz(unsigned long long l) { return frequency<yoctohertz, std::int64_t>(l); }
-constexpr auto operator"" q_yHz(long double l) { return frequency<yoctohertz, long double>(l); }
+constexpr auto operator"" _q_yHz(unsigned long long l) { return frequency<yoctohertz, std::int64_t>(l); }
+constexpr auto operator"" _q_yHz(long double l) { return frequency<yoctohertz, long double>(l); }
 
 // zHz
-constexpr auto operator"" q_zHz(unsigned long long l) { return frequency<zeptohertz, std::int64_t>(l); }
-constexpr auto operator"" q_zHz(long double l) { return frequency<zeptohertz, long double>(l); }
+constexpr auto operator"" _q_zHz(unsigned long long l) { return frequency<zeptohertz, std::int64_t>(l); }
+constexpr auto operator"" _q_zHz(long double l) { return frequency<zeptohertz, long double>(l); }
 
 // aHz
-constexpr auto operator"" q_aHz(unsigned long long l) { return frequency<attohertz, std::int64_t>(l); }
-constexpr auto operator"" q_aHz(long double l) { return frequency<attohertz, long double>(l); }
+constexpr auto operator"" _q_aHz(unsigned long long l) { return frequency<attohertz, std::int64_t>(l); }
+constexpr auto operator"" _q_aHz(long double l) { return frequency<attohertz, long double>(l); }
 
 // fHz
-constexpr auto operator"" q_fHz(unsigned long long l) { return frequency<femtohertz, std::int64_t>(l); }
-constexpr auto operator"" q_fHz(long double l) { return frequency<femtohertz, long double>(l); }
+constexpr auto operator"" _q_fHz(unsigned long long l) { return frequency<femtohertz, std::int64_t>(l); }
+constexpr auto operator"" _q_fHz(long double l) { return frequency<femtohertz, long double>(l); }
 
 // pHz
-constexpr auto operator"" q_pHz(unsigned long long l) { return frequency<picohertz, std::int64_t>(l); }
-constexpr auto operator"" q_pHz(long double l) { return frequency<picohertz, long double>(l); }
+constexpr auto operator"" _q_pHz(unsigned long long l) { return frequency<picohertz, std::int64_t>(l); }
+constexpr auto operator"" _q_pHz(long double l) { return frequency<picohertz, long double>(l); }
 
 // nHz
-constexpr auto operator"" q_nHz(unsigned long long l) { return frequency<nanohertz, std::int64_t>(l); }
-constexpr auto operator"" q_nHz(long double l) { return frequency<nanohertz, long double>(l); }
+constexpr auto operator"" _q_nHz(unsigned long long l) { return frequency<nanohertz, std::int64_t>(l); }
+constexpr auto operator"" _q_nHz(long double l) { return frequency<nanohertz, long double>(l); }
 
 // uHz
-constexpr auto operator"" q_uHz(unsigned long long l) { return frequency<microhertz, std::int64_t>(l); }
-constexpr auto operator"" q_uHz(long double l) { return frequency<microhertz, long double>(l); }
+constexpr auto operator"" _q_uHz(unsigned long long l) { return frequency<microhertz, std::int64_t>(l); }
+constexpr auto operator"" _q_uHz(long double l) { return frequency<microhertz, long double>(l); }
 
 // mHz
-constexpr auto operator"" q_mHz(unsigned long long l) { return frequency<millihertz, std::int64_t>(l); }
-constexpr auto operator"" q_mHz(long double l) { return frequency<millihertz, long double>(l); }
+constexpr auto operator"" _q_mHz(unsigned long long l) { return frequency<millihertz, std::int64_t>(l); }
+constexpr auto operator"" _q_mHz(long double l) { return frequency<millihertz, long double>(l); }
 
 // kHz
-constexpr auto operator"" q_kHz(unsigned long long l) { return frequency<kilohertz, std::int64_t>(l); }
-constexpr auto operator"" q_kHz(long double l) { return frequency<kilohertz, long double>(l); }
+constexpr auto operator"" _q_kHz(unsigned long long l) { return frequency<kilohertz, std::int64_t>(l); }
+constexpr auto operator"" _q_kHz(long double l) { return frequency<kilohertz, long double>(l); }
 
 // MHz
-constexpr auto operator"" q_MHz(unsigned long long l) { return frequency<megahertz, std::int64_t>(l); }
-constexpr auto operator"" q_MHz(long double l) { return frequency<megahertz, long double>(l); }
+constexpr auto operator"" _q_MHz(unsigned long long l) { return frequency<megahertz, std::int64_t>(l); }
+constexpr auto operator"" _q_MHz(long double l) { return frequency<megahertz, long double>(l); }
 
 // GHz
-constexpr auto operator"" q_GHz(unsigned long long l) { return frequency<gigahertz, std::int64_t>(l); }
-constexpr auto operator"" q_GHz(long double l) { return frequency<gigahertz, long double>(l); }
+constexpr auto operator"" _q_GHz(unsigned long long l) { return frequency<gigahertz, std::int64_t>(l); }
+constexpr auto operator"" _q_GHz(long double l) { return frequency<gigahertz, long double>(l); }
 
 // THz
-constexpr auto operator"" q_THz(unsigned long long l) { return frequency<terahertz, std::int64_t>(l); }
-constexpr auto operator"" q_THz(long double l) { return frequency<terahertz, long double>(l); }
+constexpr auto operator"" _q_THz(unsigned long long l) { return frequency<terahertz, std::int64_t>(l); }
+constexpr auto operator"" _q_THz(long double l) { return frequency<terahertz, long double>(l); }
 
 // PHz
-constexpr auto operator"" q_PHz(unsigned long long l) { return frequency<petahertz, std::int64_t>(l); }
-constexpr auto operator"" q_PHz(long double l) { return frequency<petahertz, long double>(l); }
+constexpr auto operator"" _q_PHz(unsigned long long l) { return frequency<petahertz, std::int64_t>(l); }
+constexpr auto operator"" _q_PHz(long double l) { return frequency<petahertz, long double>(l); }
 
 // EHz
-constexpr auto operator"" q_EHz(unsigned long long l) { return frequency<exahertz, std::int64_t>(l); }
-constexpr auto operator"" q_EHz(long double l) { return frequency<exahertz, long double>(l); }
+constexpr auto operator"" _q_EHz(unsigned long long l) { return frequency<exahertz, std::int64_t>(l); }
+constexpr auto operator"" _q_EHz(long double l) { return frequency<exahertz, long double>(l); }
 
 // ZHz
-constexpr auto operator"" q_ZHz(unsigned long long l) { return frequency<zettahertz, std::int64_t>(l); }
-constexpr auto operator"" q_ZHz(long double l) { return frequency<zettahertz, long double>(l); }
+constexpr auto operator"" _q_ZHz(unsigned long long l) { return frequency<zettahertz, std::int64_t>(l); }
+constexpr auto operator"" _q_ZHz(long double l) { return frequency<zettahertz, long double>(l); }
 
 // YHz
-constexpr auto operator"" q_YHz(unsigned long long l) { return frequency<yottahertz, std::int64_t>(l); }
-constexpr auto operator"" q_YHz(long double l) { return frequency<yottahertz, long double>(l); }
+constexpr auto operator"" _q_YHz(unsigned long long l) { return frequency<yottahertz, std::int64_t>(l); }
+constexpr auto operator"" _q_YHz(long double l) { return frequency<yottahertz, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/heat_capacity.h b/src/include/units/physical/si/heat_capacity.h
index 3911dc59..880a3b71 100644
--- a/src/include/units/physical/si/heat_capacity.h
+++ b/src/include/units/physical/si/heat_capacity.h
@@ -51,16 +51,16 @@ using molar_heat_capacity = quantity<dim_molar_heat_capacity, U, Rep>;
 inline namespace literals {
 
 // J/K
-constexpr auto operator"" q_J_per_K(unsigned long long l) { return heat_capacity<joule_per_kelvin, std::int64_t>(l); }
-constexpr auto operator"" q_J_per_K(long double l) { return heat_capacity<joule_per_kelvin, long double>(l); }
+constexpr auto operator"" _q_J_per_K(unsigned long long l) { return heat_capacity<joule_per_kelvin, std::int64_t>(l); }
+constexpr auto operator"" _q_J_per_K(long double l) { return heat_capacity<joule_per_kelvin, long double>(l); }
 
 // J/(kg·K)
-constexpr auto operator"" q_J_per_kg_K(unsigned long long l) { return specific_heat_capacity<joule_per_kilogram_kelvin, std::int64_t>(l); }
-constexpr auto operator"" q_J_per_kg_K(long double l) { return specific_heat_capacity<joule_per_kilogram_kelvin, long double>(l); }
+constexpr auto operator"" _q_J_per_kg_K(unsigned long long l) { return specific_heat_capacity<joule_per_kilogram_kelvin, std::int64_t>(l); }
+constexpr auto operator"" _q_J_per_kg_K(long double l) { return specific_heat_capacity<joule_per_kilogram_kelvin, long double>(l); }
 
 // J/(mol·K)
-constexpr auto operator"" q_J_per_mol_K(unsigned long long l) { return molar_heat_capacity<joule_per_mole_kelvin, std::int64_t>(l); }
-constexpr auto operator"" q_J_per_mol_K(long double l) { return molar_heat_capacity<joule_per_mole_kelvin, long double>(l); }
+constexpr auto operator"" _q_J_per_mol_K(unsigned long long l) { return molar_heat_capacity<joule_per_mole_kelvin, std::int64_t>(l); }
+constexpr auto operator"" _q_J_per_mol_K(long double l) { return molar_heat_capacity<joule_per_mole_kelvin, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/inductance.h b/src/include/units/physical/si/inductance.h
index 5a100fa6..f14c3798 100644
--- a/src/include/units/physical/si/inductance.h
+++ b/src/include/units/physical/si/inductance.h
@@ -56,72 +56,72 @@ using inductance = quantity<dim_inductance, U, Rep>;
 inline namespace literals {
 
 // H
-constexpr auto operator"" q_H(unsigned long long l) { return inductance<henry, std::int64_t>(l); }
-constexpr auto operator"" q_H(long double l) { return inductance<henry, long double>(l); }
+constexpr auto operator"" _q_H(unsigned long long l) { return inductance<henry, std::int64_t>(l); }
+constexpr auto operator"" _q_H(long double l) { return inductance<henry, long double>(l); }
 
 // yH
-constexpr auto operator"" q_yH(unsigned long long l) { return inductance<yoctohenry, std::int64_t>(l); }
-constexpr auto operator"" q_yH(long double l) { return inductance<yoctohenry, long double>(l); }
+constexpr auto operator"" _q_yH(unsigned long long l) { return inductance<yoctohenry, std::int64_t>(l); }
+constexpr auto operator"" _q_yH(long double l) { return inductance<yoctohenry, long double>(l); }
 
 // zH
-constexpr auto operator"" q_zH(unsigned long long l) { return inductance<zeptohenry, std::int64_t>(l); }
-constexpr auto operator"" q_zH(long double l) { return inductance<zeptohenry, long double>(l); }
+constexpr auto operator"" _q_zH(unsigned long long l) { return inductance<zeptohenry, std::int64_t>(l); }
+constexpr auto operator"" _q_zH(long double l) { return inductance<zeptohenry, long double>(l); }
 
 // aH
-constexpr auto operator"" q_aH(unsigned long long l) { return inductance<attohenry, std::int64_t>(l); }
-constexpr auto operator"" q_aH(long double l) { return inductance<attohenry, long double>(l); }
+constexpr auto operator"" _q_aH(unsigned long long l) { return inductance<attohenry, std::int64_t>(l); }
+constexpr auto operator"" _q_aH(long double l) { return inductance<attohenry, long double>(l); }
 
 // fH
-constexpr auto operator"" q_fH(unsigned long long l) { return inductance<femtohenry, std::int64_t>(l); }
-constexpr auto operator"" q_fH(long double l) { return inductance<femtohenry, long double>(l); }
+constexpr auto operator"" _q_fH(unsigned long long l) { return inductance<femtohenry, std::int64_t>(l); }
+constexpr auto operator"" _q_fH(long double l) { return inductance<femtohenry, long double>(l); }
 
 // pH
-constexpr auto operator"" q_pH(unsigned long long l) { return inductance<picohenry, std::int64_t>(l); }
-constexpr auto operator"" q_pH(long double l) { return inductance<picohenry, long double>(l); }
+constexpr auto operator"" _q_pH(unsigned long long l) { return inductance<picohenry, std::int64_t>(l); }
+constexpr auto operator"" _q_pH(long double l) { return inductance<picohenry, long double>(l); }
 
 // nH
-constexpr auto operator"" q_nH(unsigned long long l) { return inductance<nanohenry, std::int64_t>(l); }
-constexpr auto operator"" q_nH(long double l) { return inductance<nanohenry, long double>(l); }
+constexpr auto operator"" _q_nH(unsigned long long l) { return inductance<nanohenry, std::int64_t>(l); }
+constexpr auto operator"" _q_nH(long double l) { return inductance<nanohenry, long double>(l); }
 
 // µH
-constexpr auto operator"" q_uH(unsigned long long l) { return inductance<microhenry, std::int64_t>(l); }
-constexpr auto operator"" q_uH(long double l) { return inductance<microhenry, long double>(l); }
+constexpr auto operator"" _q_uH(unsigned long long l) { return inductance<microhenry, std::int64_t>(l); }
+constexpr auto operator"" _q_uH(long double l) { return inductance<microhenry, long double>(l); }
 
 // mH
-constexpr auto operator"" q_mH(unsigned long long l) { return inductance<millihenry, std::int64_t>(l); }
-constexpr auto operator"" q_mH(long double l) { return inductance<millihenry, long double>(l); }
+constexpr auto operator"" _q_mH(unsigned long long l) { return inductance<millihenry, std::int64_t>(l); }
+constexpr auto operator"" _q_mH(long double l) { return inductance<millihenry, long double>(l); }
 
 // kH
-constexpr auto operator"" q_kH(unsigned long long l) { return inductance<kilohenry, std::int64_t>(l); }
-constexpr auto operator"" q_kH(long double l) { return inductance<kilohenry, long double>(l); }
+constexpr auto operator"" _q_kH(unsigned long long l) { return inductance<kilohenry, std::int64_t>(l); }
+constexpr auto operator"" _q_kH(long double l) { return inductance<kilohenry, long double>(l); }
 
 // MH
-constexpr auto operator"" q_MH(unsigned long long l) { return inductance<megahenry, std::int64_t>(l); }
-constexpr auto operator"" q_MH(long double l) { return inductance<megahenry, long double>(l); }
+constexpr auto operator"" _q_MH(unsigned long long l) { return inductance<megahenry, std::int64_t>(l); }
+constexpr auto operator"" _q_MH(long double l) { return inductance<megahenry, long double>(l); }
 
 // GH
-constexpr auto operator"" q_GH(unsigned long long l) { return inductance<gigahenry, std::int64_t>(l); }
-constexpr auto operator"" q_GH(long double l) { return inductance<gigahenry, long double>(l); }
+constexpr auto operator"" _q_GH(unsigned long long l) { return inductance<gigahenry, std::int64_t>(l); }
+constexpr auto operator"" _q_GH(long double l) { return inductance<gigahenry, long double>(l); }
 
 // TH
-constexpr auto operator"" q_TH(unsigned long long l) { return inductance<terahenry, std::int64_t>(l); }
-constexpr auto operator"" q_TH(long double l) { return inductance<terahenry, long double>(l); }
+constexpr auto operator"" _q_TH(unsigned long long l) { return inductance<terahenry, std::int64_t>(l); }
+constexpr auto operator"" _q_TH(long double l) { return inductance<terahenry, long double>(l); }
 
 // PH
-constexpr auto operator"" q_PH(unsigned long long l) { return inductance<petahenry, std::int64_t>(l); }
-constexpr auto operator"" q_PH(long double l) { return inductance<petahenry, long double>(l); }
+constexpr auto operator"" _q_PH(unsigned long long l) { return inductance<petahenry, std::int64_t>(l); }
+constexpr auto operator"" _q_PH(long double l) { return inductance<petahenry, long double>(l); }
 
 // EH
-constexpr auto operator"" q_EH(unsigned long long l) { return inductance<exahenry, std::int64_t>(l); }
-constexpr auto operator"" q_EH(long double l) { return inductance<exahenry, long double>(l); }
+constexpr auto operator"" _q_EH(unsigned long long l) { return inductance<exahenry, std::int64_t>(l); }
+constexpr auto operator"" _q_EH(long double l) { return inductance<exahenry, long double>(l); }
 
 // ZH
-constexpr auto operator"" q_ZH(unsigned long long l) { return inductance<zettahenry, std::int64_t>(l); }
-constexpr auto operator"" q_ZH(long double l) { return inductance<zettahenry, long double>(l); }
+constexpr auto operator"" _q_ZH(unsigned long long l) { return inductance<zettahenry, std::int64_t>(l); }
+constexpr auto operator"" _q_ZH(long double l) { return inductance<zettahenry, long double>(l); }
 
 // YH
-constexpr auto operator"" q_YH(unsigned long long l) { return inductance<yottahenry, std::int64_t>(l); }
-constexpr auto operator"" q_YH(long double l) { return inductance<yottahenry, long double>(l); }
+constexpr auto operator"" _q_YH(unsigned long long l) { return inductance<yottahenry, std::int64_t>(l); }
+constexpr auto operator"" _q_YH(long double l) { return inductance<yottahenry, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/length.h b/src/include/units/physical/si/length.h
index c9c7e4be..b2aae6cb 100644
--- a/src/include/units/physical/si/length.h
+++ b/src/include/units/physical/si/length.h
@@ -60,92 +60,92 @@ using length = quantity<dim_length, U, Rep>;
 inline namespace literals {
 
 // m
-constexpr auto operator"" q_m(unsigned long long l) { return length<metre, std::int64_t>(l); }
-constexpr auto operator"" q_m(long double l) { return length<metre, long double>(l); }
+constexpr auto operator"" _q_m(unsigned long long l) { return length<metre, std::int64_t>(l); }
+constexpr auto operator"" _q_m(long double l) { return length<metre, long double>(l); }
 
 // ym
-constexpr auto operator"" q_ym(unsigned long long l) { return length<yoctometre, std::int64_t>(l); }
-constexpr auto operator"" q_ym(long double l) { return length<yoctometre, long double>(l); }
+constexpr auto operator"" _q_ym(unsigned long long l) { return length<yoctometre, std::int64_t>(l); }
+constexpr auto operator"" _q_ym(long double l) { return length<yoctometre, long double>(l); }
 
 // zm
-constexpr auto operator"" q_zm(unsigned long long l) { return length<zeptometre, std::int64_t>(l); }
-constexpr auto operator"" q_zm(long double l) { return length<zeptometre, long double>(l); }
+constexpr auto operator"" _q_zm(unsigned long long l) { return length<zeptometre, std::int64_t>(l); }
+constexpr auto operator"" _q_zm(long double l) { return length<zeptometre, long double>(l); }
 
 // am
-constexpr auto operator"" q_am(unsigned long long l) { return length<attometre, std::int64_t>(l); }
-constexpr auto operator"" q_am(long double l) { return length<attometre, long double>(l); }
+constexpr auto operator"" _q_am(unsigned long long l) { return length<attometre, std::int64_t>(l); }
+constexpr auto operator"" _q_am(long double l) { return length<attometre, long double>(l); }
 
 // fm
-constexpr auto operator"" q_fm(unsigned long long l) { return length<femtometre, std::int64_t>(l); }
-constexpr auto operator"" q_fm(long double l) { return length<femtometre, long double>(l); }
+constexpr auto operator"" _q_fm(unsigned long long l) { return length<femtometre, std::int64_t>(l); }
+constexpr auto operator"" _q_fm(long double l) { return length<femtometre, long double>(l); }
 
 // pm
-constexpr auto operator"" q_pm(unsigned long long l) { return length<picometre, std::int64_t>(l); }
-constexpr auto operator"" q_pm(long double l) { return length<picometre, long double>(l); }
+constexpr auto operator"" _q_pm(unsigned long long l) { return length<picometre, std::int64_t>(l); }
+constexpr auto operator"" _q_pm(long double l) { return length<picometre, long double>(l); }
 
 // nm
-constexpr auto operator"" q_nm(unsigned long long l) { return length<nanometre, std::int64_t>(l); }
-constexpr auto operator"" q_nm(long double l) { return length<nanometre, long double>(l); }
+constexpr auto operator"" _q_nm(unsigned long long l) { return length<nanometre, std::int64_t>(l); }
+constexpr auto operator"" _q_nm(long double l) { return length<nanometre, long double>(l); }
 
 // um
-constexpr auto operator"" q_um(unsigned long long l) { return length<micrometre, std::int64_t>(l); }
-constexpr auto operator"" q_um(long double l) { return length<micrometre, long double>(l); }
+constexpr auto operator"" _q_um(unsigned long long l) { return length<micrometre, std::int64_t>(l); }
+constexpr auto operator"" _q_um(long double l) { return length<micrometre, long double>(l); }
 
 // mm
-constexpr auto operator"" q_mm(unsigned long long l) { return length<millimetre, std::int64_t>(l); }
-constexpr auto operator"" q_mm(long double l) { return length<millimetre, long double>(l); }
+constexpr auto operator"" _q_mm(unsigned long long l) { return length<millimetre, std::int64_t>(l); }
+constexpr auto operator"" _q_mm(long double l) { return length<millimetre, long double>(l); }
 
 // cm
-constexpr auto operator"" q_cm(unsigned long long l) { return length<centimetre, std::int64_t>(l); }
-constexpr auto operator"" q_cm(long double l) { return length<centimetre, long double>(l); }
+constexpr auto operator"" _q_cm(unsigned long long l) { return length<centimetre, std::int64_t>(l); }
+constexpr auto operator"" _q_cm(long double l) { return length<centimetre, long double>(l); }
 
 // dm
-constexpr auto operator"" q_dm(unsigned long long l) { return length<decimetre, std::int64_t>(l); }
-constexpr auto operator"" q_dm(long double l) { return length<decimetre, long double>(l); }
+constexpr auto operator"" _q_dm(unsigned long long l) { return length<decimetre, std::int64_t>(l); }
+constexpr auto operator"" _q_dm(long double l) { return length<decimetre, long double>(l); }
 
 // dam
-constexpr auto operator"" q_dam(unsigned long long l) { return length<decametre, std::int64_t>(l); }
-constexpr auto operator"" q_dam(long double l) { return length<decametre, long double>(l); }
+constexpr auto operator"" _q_dam(unsigned long long l) { return length<decametre, std::int64_t>(l); }
+constexpr auto operator"" _q_dam(long double l) { return length<decametre, long double>(l); }
 
 // hm
-constexpr auto operator"" q_hm(unsigned long long l) { return length<hectometre, std::int64_t>(l); }
-constexpr auto operator"" q_hm(long double l) { return length<hectometre, long double>(l); }
+constexpr auto operator"" _q_hm(unsigned long long l) { return length<hectometre, std::int64_t>(l); }
+constexpr auto operator"" _q_hm(long double l) { return length<hectometre, long double>(l); }
 
 // km
-constexpr auto operator"" q_km(unsigned long long l) { return length<kilometre, std::int64_t>(l); }
-constexpr auto operator"" q_km(long double l) { return length<kilometre, long double>(l); }
+constexpr auto operator"" _q_km(unsigned long long l) { return length<kilometre, std::int64_t>(l); }
+constexpr auto operator"" _q_km(long double l) { return length<kilometre, long double>(l); }
 
 // Mm
-constexpr auto operator"" q_Mm(unsigned long long l) { return length<megametre, std::int64_t>(l); }
-constexpr auto operator"" q_Mm(long double l) { return length<megametre, long double>(l); }
+constexpr auto operator"" _q_Mm(unsigned long long l) { return length<megametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Mm(long double l) { return length<megametre, long double>(l); }
 
 // Gm
-constexpr auto operator"" q_Gm(unsigned long long l) { return length<gigametre, std::int64_t>(l); }
-constexpr auto operator"" q_Gm(long double l) { return length<gigametre, long double>(l); }
+constexpr auto operator"" _q_Gm(unsigned long long l) { return length<gigametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Gm(long double l) { return length<gigametre, long double>(l); }
 
 // Tm
-constexpr auto operator"" q_Tm(unsigned long long l) { return length<terametre, std::int64_t>(l); }
-constexpr auto operator"" q_Tm(long double l) { return length<terametre, long double>(l); }
+constexpr auto operator"" _q_Tm(unsigned long long l) { return length<terametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Tm(long double l) { return length<terametre, long double>(l); }
 
 // Pm
-constexpr auto operator"" q_Pm(unsigned long long l) { return length<petametre, std::int64_t>(l); }
-constexpr auto operator"" q_Pm(long double l) { return length<petametre, long double>(l); }
+constexpr auto operator"" _q_Pm(unsigned long long l) { return length<petametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Pm(long double l) { return length<petametre, long double>(l); }
 
 // Em
-constexpr auto operator"" q_Em(unsigned long long l) { return length<exametre, std::int64_t>(l); }
-constexpr auto operator"" q_Em(long double l) { return length<exametre, long double>(l); }
+constexpr auto operator"" _q_Em(unsigned long long l) { return length<exametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Em(long double l) { return length<exametre, long double>(l); }
 
 // Zm
-constexpr auto operator"" q_Zm(unsigned long long l) { return length<zettametre, std::int64_t>(l); }
-constexpr auto operator"" q_Zm(long double l) { return length<zettametre, long double>(l); }
+constexpr auto operator"" _q_Zm(unsigned long long l) { return length<zettametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Zm(long double l) { return length<zettametre, long double>(l); }
 
 // Ym
-constexpr auto operator"" q_Ym(unsigned long long l) { return length<yottametre, std::int64_t>(l); }
-constexpr auto operator"" q_Ym(long double l) { return length<yottametre, long double>(l); }
+constexpr auto operator"" _q_Ym(unsigned long long l) { return length<yottametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Ym(long double l) { return length<yottametre, long double>(l); }
 
 // au
-constexpr auto operator"" q_au(unsigned long long l) { return length<astronomical_unit, std::int64_t>(l); }
-constexpr auto operator"" q_au(long double l) { return length<astronomical_unit, long double>(l); }
+constexpr auto operator"" _q_au(unsigned long long l) { return length<astronomical_unit, std::int64_t>(l); }
+constexpr auto operator"" _q_au(long double l) { return length<astronomical_unit, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/luminance.h b/src/include/units/physical/si/luminance.h
index 1f1be254..0c49866c 100644
--- a/src/include/units/physical/si/luminance.h
+++ b/src/include/units/physical/si/luminance.h
@@ -38,8 +38,8 @@ using luminance = quantity<dim_luminance, U, Rep>;
 inline namespace literals {
 
 // cd/m²
-constexpr auto operator"" q_cd_per_m2(unsigned long long l) { return luminance<candela_per_metre_sq, std::int64_t>(l); }
-constexpr auto operator"" q_cd_per_m2(long double l) { return luminance<candela_per_metre_sq, long double>(l); }
+constexpr auto operator"" _q_cd_per_m2(unsigned long long l) { return luminance<candela_per_metre_sq, std::int64_t>(l); }
+constexpr auto operator"" _q_cd_per_m2(long double l) { return luminance<candela_per_metre_sq, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/luminous_intensity.h b/src/include/units/physical/si/luminous_intensity.h
index 27396f89..82cdda12 100644
--- a/src/include/units/physical/si/luminous_intensity.h
+++ b/src/include/units/physical/si/luminous_intensity.h
@@ -58,88 +58,88 @@ using luminous_intensity = quantity<dim_luminous_intensity, U, Rep>;
 inline namespace literals {
 
 // cd
-constexpr auto operator"" q_cd(unsigned long long l) { return luminous_intensity<candela, std::int64_t>(l); }
-constexpr auto operator"" q_cd(long double l) { return luminous_intensity<candela, long double>(l); }
+constexpr auto operator"" _q_cd(unsigned long long l) { return luminous_intensity<candela, std::int64_t>(l); }
+constexpr auto operator"" _q_cd(long double l) { return luminous_intensity<candela, long double>(l); }
 
 // ycd
-constexpr auto operator"" q_ycd(unsigned long long l) { return luminous_intensity<yoctocandela, std::int64_t>(l); }
-constexpr auto operator"" q_ycd(long double l) { return luminous_intensity<yoctocandela, long double>(l); }
+constexpr auto operator"" _q_ycd(unsigned long long l) { return luminous_intensity<yoctocandela, std::int64_t>(l); }
+constexpr auto operator"" _q_ycd(long double l) { return luminous_intensity<yoctocandela, long double>(l); }
 
 // zcd
-constexpr auto operator"" q_zcd(unsigned long long l) { return luminous_intensity<zeptocandela, std::int64_t>(l); }
-constexpr auto operator"" q_zcd(long double l) { return luminous_intensity<zeptocandela, long double>(l); }
+constexpr auto operator"" _q_zcd(unsigned long long l) { return luminous_intensity<zeptocandela, std::int64_t>(l); }
+constexpr auto operator"" _q_zcd(long double l) { return luminous_intensity<zeptocandela, long double>(l); }
 
 // acd
-constexpr auto operator"" q_acd(unsigned long long l) { return luminous_intensity<attocandela, std::int64_t>(l); }
-constexpr auto operator"" q_acd(long double l) { return luminous_intensity<attocandela, long double>(l); }
+constexpr auto operator"" _q_acd(unsigned long long l) { return luminous_intensity<attocandela, std::int64_t>(l); }
+constexpr auto operator"" _q_acd(long double l) { return luminous_intensity<attocandela, long double>(l); }
 
 // fcd
-constexpr auto operator"" q_fcd(unsigned long long l) { return luminous_intensity<femtocandela, std::int64_t>(l); }
-constexpr auto operator"" q_fcd(long double l) { return luminous_intensity<femtocandela, long double>(l); }
+constexpr auto operator"" _q_fcd(unsigned long long l) { return luminous_intensity<femtocandela, std::int64_t>(l); }
+constexpr auto operator"" _q_fcd(long double l) { return luminous_intensity<femtocandela, long double>(l); }
 
 // pcd
-constexpr auto operator"" q_pcd(unsigned long long l) { return luminous_intensity<picocandela, std::int64_t>(l); }
-constexpr auto operator"" q_pcd(long double l) { return luminous_intensity<picocandela, long double>(l); }
+constexpr auto operator"" _q_pcd(unsigned long long l) { return luminous_intensity<picocandela, std::int64_t>(l); }
+constexpr auto operator"" _q_pcd(long double l) { return luminous_intensity<picocandela, long double>(l); }
 
 // ncd
-constexpr auto operator"" q_ncd(unsigned long long l) { return luminous_intensity<nanocandela, std::int64_t>(l); }
-constexpr auto operator"" q_ncd(long double l) { return luminous_intensity<nanocandela, long double>(l); }
+constexpr auto operator"" _q_ncd(unsigned long long l) { return luminous_intensity<nanocandela, std::int64_t>(l); }
+constexpr auto operator"" _q_ncd(long double l) { return luminous_intensity<nanocandela, long double>(l); }
 
 // ucd
-constexpr auto operator"" q_ucd(unsigned long long l) { return luminous_intensity<microcandela, std::int64_t>(l); }
-constexpr auto operator"" q_ucd(long double l) { return luminous_intensity<microcandela, long double>(l); }
+constexpr auto operator"" _q_ucd(unsigned long long l) { return luminous_intensity<microcandela, std::int64_t>(l); }
+constexpr auto operator"" _q_ucd(long double l) { return luminous_intensity<microcandela, long double>(l); }
 
 // mcd
-constexpr auto operator"" q_mcd(unsigned long long l) { return luminous_intensity<millicandela, std::int64_t>(l); }
-constexpr auto operator"" q_mcd(long double l) { return luminous_intensity<millicandela, long double>(l); }
+constexpr auto operator"" _q_mcd(unsigned long long l) { return luminous_intensity<millicandela, std::int64_t>(l); }
+constexpr auto operator"" _q_mcd(long double l) { return luminous_intensity<millicandela, long double>(l); }
 
 // ccd
-constexpr auto operator"" q_ccd(unsigned long long l) { return luminous_intensity<centicandela, std::int64_t>(l); }
-constexpr auto operator"" q_ccd(long double l) { return luminous_intensity<centicandela, long double>(l); }
+constexpr auto operator"" _q_ccd(unsigned long long l) { return luminous_intensity<centicandela, std::int64_t>(l); }
+constexpr auto operator"" _q_ccd(long double l) { return luminous_intensity<centicandela, long double>(l); }
 
 // dcd
-constexpr auto operator"" q_dcd(unsigned long long l) { return luminous_intensity<decicandela, std::int64_t>(l); }
-constexpr auto operator"" q_dcd(long double l) { return luminous_intensity<decicandela, long double>(l); }
+constexpr auto operator"" _q_dcd(unsigned long long l) { return luminous_intensity<decicandela, std::int64_t>(l); }
+constexpr auto operator"" _q_dcd(long double l) { return luminous_intensity<decicandela, long double>(l); }
 
 // dacd
-constexpr auto operator"" q_dacd(unsigned long long l) { return luminous_intensity<decacandela, std::int64_t>(l); }
-constexpr auto operator"" q_dacd(long double l) { return luminous_intensity<decacandela, long double>(l); }
+constexpr auto operator"" _q_dacd(unsigned long long l) { return luminous_intensity<decacandela, std::int64_t>(l); }
+constexpr auto operator"" _q_dacd(long double l) { return luminous_intensity<decacandela, long double>(l); }
 
 // hcd
-constexpr auto operator"" q_hcd(unsigned long long l) { return luminous_intensity<hectocandela, std::int64_t>(l); }
-constexpr auto operator"" q_hcd(long double l) { return luminous_intensity<hectocandela, long double>(l); }
+constexpr auto operator"" _q_hcd(unsigned long long l) { return luminous_intensity<hectocandela, std::int64_t>(l); }
+constexpr auto operator"" _q_hcd(long double l) { return luminous_intensity<hectocandela, long double>(l); }
 
 // kcd
-constexpr auto operator"" q_kcd(unsigned long long l) { return luminous_intensity<kilocandela, std::int64_t>(l); }
-constexpr auto operator"" q_kcd(long double l) { return luminous_intensity<kilocandela, long double>(l); }
+constexpr auto operator"" _q_kcd(unsigned long long l) { return luminous_intensity<kilocandela, std::int64_t>(l); }
+constexpr auto operator"" _q_kcd(long double l) { return luminous_intensity<kilocandela, long double>(l); }
 
 // Mcd
-constexpr auto operator"" q_Mcd(unsigned long long l) { return luminous_intensity<megacandela, std::int64_t>(l); }
-constexpr auto operator"" q_Mcd(long double l) { return luminous_intensity<megacandela, long double>(l); }
+constexpr auto operator"" _q_Mcd(unsigned long long l) { return luminous_intensity<megacandela, std::int64_t>(l); }
+constexpr auto operator"" _q_Mcd(long double l) { return luminous_intensity<megacandela, long double>(l); }
 
 // Gcd
-constexpr auto operator"" q_Gcd(unsigned long long l) { return luminous_intensity<gigacandela, std::int64_t>(l); }
-constexpr auto operator"" q_Gcd(long double l) { return luminous_intensity<gigacandela, long double>(l); }
+constexpr auto operator"" _q_Gcd(unsigned long long l) { return luminous_intensity<gigacandela, std::int64_t>(l); }
+constexpr auto operator"" _q_Gcd(long double l) { return luminous_intensity<gigacandela, long double>(l); }
 
 // Tcd
-constexpr auto operator"" q_Tcd(unsigned long long l) { return luminous_intensity<teracandela, std::int64_t>(l); }
-constexpr auto operator"" q_Tcd(long double l) { return luminous_intensity<teracandela, long double>(l); }
+constexpr auto operator"" _q_Tcd(unsigned long long l) { return luminous_intensity<teracandela, std::int64_t>(l); }
+constexpr auto operator"" _q_Tcd(long double l) { return luminous_intensity<teracandela, long double>(l); }
 
 // Pcd
-constexpr auto operator"" q_Pcd(unsigned long long l) { return luminous_intensity<petacandela, std::int64_t>(l); }
-constexpr auto operator"" q_Pcd(long double l) { return luminous_intensity<petacandela, long double>(l); }
+constexpr auto operator"" _q_Pcd(unsigned long long l) { return luminous_intensity<petacandela, std::int64_t>(l); }
+constexpr auto operator"" _q_Pcd(long double l) { return luminous_intensity<petacandela, long double>(l); }
 
 // Ecd
-constexpr auto operator"" q_Ecd(unsigned long long l) { return luminous_intensity<exacandela, std::int64_t>(l); }
-constexpr auto operator"" q_Ecd(long double l) { return luminous_intensity<exacandela, long double>(l); }
+constexpr auto operator"" _q_Ecd(unsigned long long l) { return luminous_intensity<exacandela, std::int64_t>(l); }
+constexpr auto operator"" _q_Ecd(long double l) { return luminous_intensity<exacandela, long double>(l); }
 
 // Zcd
-constexpr auto operator"" q_Zcd(unsigned long long l) { return luminous_intensity<zettacandela, std::int64_t>(l); }
-constexpr auto operator"" q_Zcd(long double l) { return luminous_intensity<zettacandela, long double>(l); }
+constexpr auto operator"" _q_Zcd(unsigned long long l) { return luminous_intensity<zettacandela, std::int64_t>(l); }
+constexpr auto operator"" _q_Zcd(long double l) { return luminous_intensity<zettacandela, long double>(l); }
 
 // Ycd
-constexpr auto operator"" q_Ycd(unsigned long long l) { return luminous_intensity<yottacandela, std::int64_t>(l); }
-constexpr auto operator"" q_Ycd(long double l) { return luminous_intensity<yottacandela, long double>(l); }
+constexpr auto operator"" _q_Ycd(unsigned long long l) { return luminous_intensity<yottacandela, std::int64_t>(l); }
+constexpr auto operator"" _q_Ycd(long double l) { return luminous_intensity<yottacandela, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/magnetic_flux.h b/src/include/units/physical/si/magnetic_flux.h
index 3d501fbb..b1e097cb 100644
--- a/src/include/units/physical/si/magnetic_flux.h
+++ b/src/include/units/physical/si/magnetic_flux.h
@@ -56,72 +56,72 @@ using magnetic_flux = quantity<dim_magnetic_flux, U, Rep>;
 inline namespace literals {
 
 // Wb
-constexpr auto operator"" q_Wb(unsigned long long l) { return magnetic_flux<weber, std::int64_t>(l); }
-constexpr auto operator"" q_Wb(long double l) { return magnetic_flux<weber, long double>(l); }
+constexpr auto operator"" _q_Wb(unsigned long long l) { return magnetic_flux<weber, std::int64_t>(l); }
+constexpr auto operator"" _q_Wb(long double l) { return magnetic_flux<weber, long double>(l); }
 
 // yWb
-constexpr auto operator"" q_yWb(unsigned long long l) { return magnetic_flux<yoctoweber, std::int64_t>(l); }
-constexpr auto operator"" q_yWb(long double l) { return magnetic_flux<yoctoweber, long double>(l); }
+constexpr auto operator"" _q_yWb(unsigned long long l) { return magnetic_flux<yoctoweber, std::int64_t>(l); }
+constexpr auto operator"" _q_yWb(long double l) { return magnetic_flux<yoctoweber, long double>(l); }
 
 // zWb
-constexpr auto operator"" q_zWb(unsigned long long l) { return magnetic_flux<zeptoweber, std::int64_t>(l); }
-constexpr auto operator"" q_zWb(long double l) { return magnetic_flux<zeptoweber, long double>(l); }
+constexpr auto operator"" _q_zWb(unsigned long long l) { return magnetic_flux<zeptoweber, std::int64_t>(l); }
+constexpr auto operator"" _q_zWb(long double l) { return magnetic_flux<zeptoweber, long double>(l); }
 
 // aWb
-constexpr auto operator"" q_aWb(unsigned long long l) { return magnetic_flux<attoweber, std::int64_t>(l); }
-constexpr auto operator"" q_aWb(long double l) { return magnetic_flux<attoweber, long double>(l); }
+constexpr auto operator"" _q_aWb(unsigned long long l) { return magnetic_flux<attoweber, std::int64_t>(l); }
+constexpr auto operator"" _q_aWb(long double l) { return magnetic_flux<attoweber, long double>(l); }
 
 // fWb
-constexpr auto operator"" q_fWb(unsigned long long l) { return magnetic_flux<femtoweber, std::int64_t>(l); }
-constexpr auto operator"" q_fWb(long double l) { return magnetic_flux<femtoweber, long double>(l); }
+constexpr auto operator"" _q_fWb(unsigned long long l) { return magnetic_flux<femtoweber, std::int64_t>(l); }
+constexpr auto operator"" _q_fWb(long double l) { return magnetic_flux<femtoweber, long double>(l); }
 
 // pWb
-constexpr auto operator"" q_pWb(unsigned long long l) { return magnetic_flux<picoweber, std::int64_t>(l); }
-constexpr auto operator"" q_pWb(long double l) { return magnetic_flux<picoweber, long double>(l); }
+constexpr auto operator"" _q_pWb(unsigned long long l) { return magnetic_flux<picoweber, std::int64_t>(l); }
+constexpr auto operator"" _q_pWb(long double l) { return magnetic_flux<picoweber, long double>(l); }
 
 // nWb
-constexpr auto operator"" q_nWb(unsigned long long l) { return magnetic_flux<nanoweber, std::int64_t>(l); }
-constexpr auto operator"" q_nWb(long double l) { return magnetic_flux<nanoweber, long double>(l); }
+constexpr auto operator"" _q_nWb(unsigned long long l) { return magnetic_flux<nanoweber, std::int64_t>(l); }
+constexpr auto operator"" _q_nWb(long double l) { return magnetic_flux<nanoweber, long double>(l); }
 
 // µWb
-constexpr auto operator"" q_uWb(unsigned long long l) { return magnetic_flux<microweber, std::int64_t>(l); }
-constexpr auto operator"" q_uWb(long double l) { return magnetic_flux<microweber, long double>(l); }
+constexpr auto operator"" _q_uWb(unsigned long long l) { return magnetic_flux<microweber, std::int64_t>(l); }
+constexpr auto operator"" _q_uWb(long double l) { return magnetic_flux<microweber, long double>(l); }
 
 // mWb
-constexpr auto operator"" q_mWb(unsigned long long l) { return magnetic_flux<milliweber, std::int64_t>(l); }
-constexpr auto operator"" q_mWb(long double l) { return magnetic_flux<milliweber, long double>(l); }
+constexpr auto operator"" _q_mWb(unsigned long long l) { return magnetic_flux<milliweber, std::int64_t>(l); }
+constexpr auto operator"" _q_mWb(long double l) { return magnetic_flux<milliweber, long double>(l); }
 
 // kWb
-constexpr auto operator"" q_kWb(unsigned long long l) { return magnetic_flux<kiloweber, std::int64_t>(l); }
-constexpr auto operator"" q_kWb(long double l) { return magnetic_flux<kiloweber, long double>(l); }
+constexpr auto operator"" _q_kWb(unsigned long long l) { return magnetic_flux<kiloweber, std::int64_t>(l); }
+constexpr auto operator"" _q_kWb(long double l) { return magnetic_flux<kiloweber, long double>(l); }
 
 // MWb
-constexpr auto operator"" q_MWb(unsigned long long l) { return magnetic_flux<megaweber, std::int64_t>(l); }
-constexpr auto operator"" q_MWb(long double l) { return magnetic_flux<megaweber, long double>(l); }
+constexpr auto operator"" _q_MWb(unsigned long long l) { return magnetic_flux<megaweber, std::int64_t>(l); }
+constexpr auto operator"" _q_MWb(long double l) { return magnetic_flux<megaweber, long double>(l); }
 
 // GWb
-constexpr auto operator"" q_GWb(unsigned long long l) { return magnetic_flux<gigaweber, std::int64_t>(l); }
-constexpr auto operator"" q_GWb(long double l) { return magnetic_flux<gigaweber, long double>(l); }
+constexpr auto operator"" _q_GWb(unsigned long long l) { return magnetic_flux<gigaweber, std::int64_t>(l); }
+constexpr auto operator"" _q_GWb(long double l) { return magnetic_flux<gigaweber, long double>(l); }
 
 // TWb
-constexpr auto operator"" q_TWb(unsigned long long l) { return magnetic_flux<teraweber, std::int64_t>(l); }
-constexpr auto operator"" q_TWb(long double l) { return magnetic_flux<teraweber, long double>(l); }
+constexpr auto operator"" _q_TWb(unsigned long long l) { return magnetic_flux<teraweber, std::int64_t>(l); }
+constexpr auto operator"" _q_TWb(long double l) { return magnetic_flux<teraweber, long double>(l); }
 
 // PWb
-constexpr auto operator"" q_PWb(unsigned long long l) { return magnetic_flux<petaweber, std::int64_t>(l); }
-constexpr auto operator"" q_PWb(long double l) { return magnetic_flux<petaweber, long double>(l); }
+constexpr auto operator"" _q_PWb(unsigned long long l) { return magnetic_flux<petaweber, std::int64_t>(l); }
+constexpr auto operator"" _q_PWb(long double l) { return magnetic_flux<petaweber, long double>(l); }
 
 // EWb
-constexpr auto operator"" q_EWb(unsigned long long l) { return magnetic_flux<exaweber, std::int64_t>(l); }
-constexpr auto operator"" q_EWb(long double l) { return magnetic_flux<exaweber, long double>(l); }
+constexpr auto operator"" _q_EWb(unsigned long long l) { return magnetic_flux<exaweber, std::int64_t>(l); }
+constexpr auto operator"" _q_EWb(long double l) { return magnetic_flux<exaweber, long double>(l); }
 
 // ZWb
-constexpr auto operator"" q_ZWb(unsigned long long l) { return magnetic_flux<zettaweber, std::int64_t>(l); }
-constexpr auto operator"" q_ZWb(long double l) { return magnetic_flux<zettaweber, long double>(l); }
+constexpr auto operator"" _q_ZWb(unsigned long long l) { return magnetic_flux<zettaweber, std::int64_t>(l); }
+constexpr auto operator"" _q_ZWb(long double l) { return magnetic_flux<zettaweber, long double>(l); }
 
 // YWb
-constexpr auto operator"" q_YWb(unsigned long long l) { return magnetic_flux<yottaweber, std::int64_t>(l); }
-constexpr auto operator"" q_YWb(long double l) { return magnetic_flux<yottaweber, long double>(l); }
+constexpr auto operator"" _q_YWb(unsigned long long l) { return magnetic_flux<yottaweber, std::int64_t>(l); }
+constexpr auto operator"" _q_YWb(long double l) { return magnetic_flux<yottaweber, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/magnetic_induction.h b/src/include/units/physical/si/magnetic_induction.h
index 9d631e4e..7cfd15fe 100644
--- a/src/include/units/physical/si/magnetic_induction.h
+++ b/src/include/units/physical/si/magnetic_induction.h
@@ -60,76 +60,76 @@ using magnetic_induction = quantity<dim_magnetic_induction, U, Rep>;
 inline namespace literals {
 
 // T
-constexpr auto operator"" q_T(unsigned long long l) { return magnetic_induction<tesla, std::int64_t>(l); }
-constexpr auto operator"" q_T(long double l) { return magnetic_induction<tesla, long double>(l); }
+constexpr auto operator"" _q_T(unsigned long long l) { return magnetic_induction<tesla, std::int64_t>(l); }
+constexpr auto operator"" _q_T(long double l) { return magnetic_induction<tesla, long double>(l); }
 
 // yT
-constexpr auto operator"" q_yT(unsigned long long l) { return magnetic_induction<yoctotesla, std::int64_t>(l); }
-constexpr auto operator"" q_yT(long double l) { return magnetic_induction<yoctotesla, long double>(l); }
+constexpr auto operator"" _q_yT(unsigned long long l) { return magnetic_induction<yoctotesla, std::int64_t>(l); }
+constexpr auto operator"" _q_yT(long double l) { return magnetic_induction<yoctotesla, long double>(l); }
 
 // zT
-constexpr auto operator"" q_zT(unsigned long long l) { return magnetic_induction<zeptotesla, std::int64_t>(l); }
-constexpr auto operator"" q_zT(long double l) { return magnetic_induction<zeptotesla, long double>(l); }
+constexpr auto operator"" _q_zT(unsigned long long l) { return magnetic_induction<zeptotesla, std::int64_t>(l); }
+constexpr auto operator"" _q_zT(long double l) { return magnetic_induction<zeptotesla, long double>(l); }
 
 // aT
-constexpr auto operator"" q_aT(unsigned long long l) { return magnetic_induction<attotesla, std::int64_t>(l); }
-constexpr auto operator"" q_aT(long double l) { return magnetic_induction<attotesla, long double>(l); }
+constexpr auto operator"" _q_aT(unsigned long long l) { return magnetic_induction<attotesla, std::int64_t>(l); }
+constexpr auto operator"" _q_aT(long double l) { return magnetic_induction<attotesla, long double>(l); }
 
 // fT
-constexpr auto operator"" q_fT(unsigned long long l) { return magnetic_induction<femtotesla, std::int64_t>(l); }
-constexpr auto operator"" q_fT(long double l) { return magnetic_induction<femtotesla, long double>(l); }
+constexpr auto operator"" _q_fT(unsigned long long l) { return magnetic_induction<femtotesla, std::int64_t>(l); }
+constexpr auto operator"" _q_fT(long double l) { return magnetic_induction<femtotesla, long double>(l); }
 
 // pT
-constexpr auto operator"" q_pT(unsigned long long l) { return magnetic_induction<picotesla, std::int64_t>(l); }
-constexpr auto operator"" q_pT(long double l) { return magnetic_induction<picotesla, long double>(l); }
+constexpr auto operator"" _q_pT(unsigned long long l) { return magnetic_induction<picotesla, std::int64_t>(l); }
+constexpr auto operator"" _q_pT(long double l) { return magnetic_induction<picotesla, long double>(l); }
 
 // nT
-constexpr auto operator"" q_nT(unsigned long long l) { return magnetic_induction<nanotesla, std::int64_t>(l); }
-constexpr auto operator"" q_nT(long double l) { return magnetic_induction<nanotesla, long double>(l); }
+constexpr auto operator"" _q_nT(unsigned long long l) { return magnetic_induction<nanotesla, std::int64_t>(l); }
+constexpr auto operator"" _q_nT(long double l) { return magnetic_induction<nanotesla, long double>(l); }
 
 // µT
-constexpr auto operator"" q_uT(unsigned long long l) { return magnetic_induction<microtesla, std::int64_t>(l); }
-constexpr auto operator"" q_uT(long double l) { return magnetic_induction<microtesla, long double>(l); }
+constexpr auto operator"" _q_uT(unsigned long long l) { return magnetic_induction<microtesla, std::int64_t>(l); }
+constexpr auto operator"" _q_uT(long double l) { return magnetic_induction<microtesla, long double>(l); }
 
 // mT
-constexpr auto operator"" q_mT(unsigned long long l) { return magnetic_induction<millitesla, std::int64_t>(l); }
-constexpr auto operator"" q_mT(long double l) { return magnetic_induction<millitesla, long double>(l); }
+constexpr auto operator"" _q_mT(unsigned long long l) { return magnetic_induction<millitesla, std::int64_t>(l); }
+constexpr auto operator"" _q_mT(long double l) { return magnetic_induction<millitesla, long double>(l); }
 
 // kT
-constexpr auto operator"" q_kT(unsigned long long l) { return magnetic_induction<kilotesla, std::int64_t>(l); }
-constexpr auto operator"" q_kT(long double l) { return magnetic_induction<kilotesla, long double>(l); }
+constexpr auto operator"" _q_kT(unsigned long long l) { return magnetic_induction<kilotesla, std::int64_t>(l); }
+constexpr auto operator"" _q_kT(long double l) { return magnetic_induction<kilotesla, long double>(l); }
 
 // MT
-constexpr auto operator"" q_MT(unsigned long long l) { return magnetic_induction<megatesla, std::int64_t>(l); }
-constexpr auto operator"" q_MT(long double l) { return magnetic_induction<megatesla, long double>(l); }
+constexpr auto operator"" _q_MT(unsigned long long l) { return magnetic_induction<megatesla, std::int64_t>(l); }
+constexpr auto operator"" _q_MT(long double l) { return magnetic_induction<megatesla, long double>(l); }
 
 // GT
-constexpr auto operator"" q_GT(unsigned long long l) { return magnetic_induction<gigatesla, std::int64_t>(l); }
-constexpr auto operator"" q_GT(long double l) { return magnetic_induction<gigatesla, long double>(l); }
+constexpr auto operator"" _q_GT(unsigned long long l) { return magnetic_induction<gigatesla, std::int64_t>(l); }
+constexpr auto operator"" _q_GT(long double l) { return magnetic_induction<gigatesla, long double>(l); }
 
 // TT
-constexpr auto operator"" q_TT(unsigned long long l) { return magnetic_induction<teratesla, std::int64_t>(l); }
-constexpr auto operator"" q_TT(long double l) { return magnetic_induction<teratesla, long double>(l); }
+constexpr auto operator"" _q_TT(unsigned long long l) { return magnetic_induction<teratesla, std::int64_t>(l); }
+constexpr auto operator"" _q_TT(long double l) { return magnetic_induction<teratesla, long double>(l); }
 
 // PT
-constexpr auto operator"" q_PT(unsigned long long l) { return magnetic_induction<petatesla, std::int64_t>(l); }
-constexpr auto operator"" q_PT(long double l) { return magnetic_induction<petatesla, long double>(l); }
+constexpr auto operator"" _q_PT(unsigned long long l) { return magnetic_induction<petatesla, std::int64_t>(l); }
+constexpr auto operator"" _q_PT(long double l) { return magnetic_induction<petatesla, long double>(l); }
 
 // ET
-constexpr auto operator"" q_ET(unsigned long long l) { return magnetic_induction<exatesla, std::int64_t>(l); }
-constexpr auto operator"" q_ET(long double l) { return magnetic_induction<exatesla, long double>(l); }
+constexpr auto operator"" _q_ET(unsigned long long l) { return magnetic_induction<exatesla, std::int64_t>(l); }
+constexpr auto operator"" _q_ET(long double l) { return magnetic_induction<exatesla, long double>(l); }
 
 // ZT
-constexpr auto operator"" q_ZT(unsigned long long l) { return magnetic_induction<zettatesla, std::int64_t>(l); }
-constexpr auto operator"" q_ZT(long double l) { return magnetic_induction<zettatesla, long double>(l); }
+constexpr auto operator"" _q_ZT(unsigned long long l) { return magnetic_induction<zettatesla, std::int64_t>(l); }
+constexpr auto operator"" _q_ZT(long double l) { return magnetic_induction<zettatesla, long double>(l); }
 
 // YT
-constexpr auto operator"" q_YT(unsigned long long l) { return magnetic_induction<yottatesla, std::int64_t>(l); }
-constexpr auto operator"" q_YT(long double l) { return magnetic_induction<yottatesla, long double>(l); }
+constexpr auto operator"" _q_YT(unsigned long long l) { return magnetic_induction<yottatesla, std::int64_t>(l); }
+constexpr auto operator"" _q_YT(long double l) { return magnetic_induction<yottatesla, long double>(l); }
 
 // G
-constexpr auto operator"" q_G(unsigned long long l) { return magnetic_induction<gauss, std::int64_t>(l); }
-constexpr auto operator"" q_G(long double l) { return magnetic_induction<gauss, long double>(l); }
+constexpr auto operator"" _q_G(unsigned long long l) { return magnetic_induction<gauss, std::int64_t>(l); }
+constexpr auto operator"" _q_G(long double l) { return magnetic_induction<gauss, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/mass.h b/src/include/units/physical/si/mass.h
index 8ff950da..d39e7417 100644
--- a/src/include/units/physical/si/mass.h
+++ b/src/include/units/physical/si/mass.h
@@ -82,176 +82,176 @@ using mass = quantity<dim_mass, U, Rep>;
 inline namespace literals {
 
 // g
-constexpr auto operator"" q_g(unsigned long long l) { return mass<gram, std::int64_t>(l); }
-constexpr auto operator"" q_g(long double l) { return mass<gram, long double>(l); }
+constexpr auto operator"" _q_g(unsigned long long l) { return mass<gram, std::int64_t>(l); }
+constexpr auto operator"" _q_g(long double l) { return mass<gram, long double>(l); }
 
 // yg
-constexpr auto operator"" q_yg(unsigned long long l) { return mass<yoctogram, std::int64_t>(l); }
-constexpr auto operator"" q_yg(long double l) { return mass<yoctogram, long double>(l); }
+constexpr auto operator"" _q_yg(unsigned long long l) { return mass<yoctogram, std::int64_t>(l); }
+constexpr auto operator"" _q_yg(long double l) { return mass<yoctogram, long double>(l); }
 
 // zg
-constexpr auto operator"" q_zg(unsigned long long l) { return mass<zeptogram, std::int64_t>(l); }
-constexpr auto operator"" q_zg(long double l) { return mass<zeptogram, long double>(l); }
+constexpr auto operator"" _q_zg(unsigned long long l) { return mass<zeptogram, std::int64_t>(l); }
+constexpr auto operator"" _q_zg(long double l) { return mass<zeptogram, long double>(l); }
 
 // ag
-constexpr auto operator"" q_ag(unsigned long long l) { return mass<attogram, std::int64_t>(l); }
-constexpr auto operator"" q_ag(long double l) { return mass<attogram, long double>(l); }
+constexpr auto operator"" _q_ag(unsigned long long l) { return mass<attogram, std::int64_t>(l); }
+constexpr auto operator"" _q_ag(long double l) { return mass<attogram, long double>(l); }
 
 // fg
-constexpr auto operator"" q_fg(unsigned long long l) { return mass<femtogram, std::int64_t>(l); }
-constexpr auto operator"" q_fg(long double l) { return mass<femtogram, long double>(l); }
+constexpr auto operator"" _q_fg(unsigned long long l) { return mass<femtogram, std::int64_t>(l); }
+constexpr auto operator"" _q_fg(long double l) { return mass<femtogram, long double>(l); }
 
 // pg
-constexpr auto operator"" q_pg(unsigned long long l) { return mass<picogram, std::int64_t>(l); }
-constexpr auto operator"" q_pg(long double l) { return mass<picogram, long double>(l); }
+constexpr auto operator"" _q_pg(unsigned long long l) { return mass<picogram, std::int64_t>(l); }
+constexpr auto operator"" _q_pg(long double l) { return mass<picogram, long double>(l); }
 
 // ng
-constexpr auto operator"" q_ng(unsigned long long l) { return mass<nanogram, std::int64_t>(l); }
-constexpr auto operator"" q_ng(long double l) { return mass<nanogram, long double>(l); }
+constexpr auto operator"" _q_ng(unsigned long long l) { return mass<nanogram, std::int64_t>(l); }
+constexpr auto operator"" _q_ng(long double l) { return mass<nanogram, long double>(l); }
 
 // ug
-constexpr auto operator"" q_ug(unsigned long long l) { return mass<microgram, std::int64_t>(l); }
-constexpr auto operator"" q_ug(long double l) { return mass<microgram, long double>(l); }
+constexpr auto operator"" _q_ug(unsigned long long l) { return mass<microgram, std::int64_t>(l); }
+constexpr auto operator"" _q_ug(long double l) { return mass<microgram, long double>(l); }
 
 // mg
-constexpr auto operator"" q_mg(unsigned long long l) { return mass<milligram, std::int64_t>(l); }
-constexpr auto operator"" q_mg(long double l) { return mass<milligram, long double>(l); }
+constexpr auto operator"" _q_mg(unsigned long long l) { return mass<milligram, std::int64_t>(l); }
+constexpr auto operator"" _q_mg(long double l) { return mass<milligram, long double>(l); }
 
 // cg
-constexpr auto operator"" q_cg(unsigned long long l) { return mass<centigram, std::int64_t>(l); }
-constexpr auto operator"" q_cg(long double l) { return mass<centigram, long double>(l); }
+constexpr auto operator"" _q_cg(unsigned long long l) { return mass<centigram, std::int64_t>(l); }
+constexpr auto operator"" _q_cg(long double l) { return mass<centigram, long double>(l); }
 
 // dg
-constexpr auto operator"" q_dg(unsigned long long l) { return mass<decigram, std::int64_t>(l); }
-constexpr auto operator"" q_dg(long double l) { return mass<decigram, long double>(l); }
+constexpr auto operator"" _q_dg(unsigned long long l) { return mass<decigram, std::int64_t>(l); }
+constexpr auto operator"" _q_dg(long double l) { return mass<decigram, long double>(l); }
 
 // dag
-constexpr auto operator"" q_dag(unsigned long long l) { return mass<decagram, std::int64_t>(l); }
-constexpr auto operator"" q_dag(long double l) { return mass<decagram, long double>(l); }
+constexpr auto operator"" _q_dag(unsigned long long l) { return mass<decagram, std::int64_t>(l); }
+constexpr auto operator"" _q_dag(long double l) { return mass<decagram, long double>(l); }
 
 // hg
-constexpr auto operator"" q_hg(unsigned long long l) { return mass<hectogram, std::int64_t>(l); }
-constexpr auto operator"" q_hg(long double l) { return mass<hectogram, long double>(l); }
+constexpr auto operator"" _q_hg(unsigned long long l) { return mass<hectogram, std::int64_t>(l); }
+constexpr auto operator"" _q_hg(long double l) { return mass<hectogram, long double>(l); }
 
 // kg
-constexpr auto operator"" q_kg(unsigned long long l) { return mass<kilogram, std::int64_t>(l); }
-constexpr auto operator"" q_kg(long double l) { return mass<kilogram, long double>(l); }
+constexpr auto operator"" _q_kg(unsigned long long l) { return mass<kilogram, std::int64_t>(l); }
+constexpr auto operator"" _q_kg(long double l) { return mass<kilogram, long double>(l); }
 
 // Mg
-constexpr auto operator"" q_Mg(unsigned long long l) { return mass<megagram, std::int64_t>(l); }
-constexpr auto operator"" q_Mg(long double l) { return mass<megagram, long double>(l); }
+constexpr auto operator"" _q_Mg(unsigned long long l) { return mass<megagram, std::int64_t>(l); }
+constexpr auto operator"" _q_Mg(long double l) { return mass<megagram, long double>(l); }
 
 // Gg
-constexpr auto operator"" q_Gg(unsigned long long l) { return mass<gigagram, std::int64_t>(l); }
-constexpr auto operator"" q_Gg(long double l) { return mass<gigagram, long double>(l); }
+constexpr auto operator"" _q_Gg(unsigned long long l) { return mass<gigagram, std::int64_t>(l); }
+constexpr auto operator"" _q_Gg(long double l) { return mass<gigagram, long double>(l); }
 
 // Tg
-constexpr auto operator"" q_Tg(unsigned long long l) { return mass<teragram, std::int64_t>(l); }
-constexpr auto operator"" q_Tg(long double l) { return mass<teragram, long double>(l); }
+constexpr auto operator"" _q_Tg(unsigned long long l) { return mass<teragram, std::int64_t>(l); }
+constexpr auto operator"" _q_Tg(long double l) { return mass<teragram, long double>(l); }
 
 // Pg
-constexpr auto operator"" q_Pg(unsigned long long l) { return mass<petagram, std::int64_t>(l); }
-constexpr auto operator"" q_Pg(long double l) { return mass<petagram, long double>(l); }
+constexpr auto operator"" _q_Pg(unsigned long long l) { return mass<petagram, std::int64_t>(l); }
+constexpr auto operator"" _q_Pg(long double l) { return mass<petagram, long double>(l); }
 
 // Eg
-constexpr auto operator"" q_Eg(unsigned long long l) { return mass<exagram, std::int64_t>(l); }
-constexpr auto operator"" q_Eg(long double l) { return mass<exagram, long double>(l); }
+constexpr auto operator"" _q_Eg(unsigned long long l) { return mass<exagram, std::int64_t>(l); }
+constexpr auto operator"" _q_Eg(long double l) { return mass<exagram, long double>(l); }
 
 // Zg
-constexpr auto operator"" q_Zg(unsigned long long l) { return mass<zettagram, std::int64_t>(l); }
-constexpr auto operator"" q_Zg(long double l) { return mass<zettagram, long double>(l); }
+constexpr auto operator"" _q_Zg(unsigned long long l) { return mass<zettagram, std::int64_t>(l); }
+constexpr auto operator"" _q_Zg(long double l) { return mass<zettagram, long double>(l); }
 
 // Yg
-constexpr auto operator"" q_Yg(unsigned long long l) { return mass<yottagram, std::int64_t>(l); }
-constexpr auto operator"" q_Yg(long double l) { return mass<yottagram, long double>(l); }
+constexpr auto operator"" _q_Yg(unsigned long long l) { return mass<yottagram, std::int64_t>(l); }
+constexpr auto operator"" _q_Yg(long double l) { return mass<yottagram, long double>(l); }
 
 // t
-constexpr auto operator"" q_t(unsigned long long l) { return mass<tonne, std::int64_t>(l); }
-constexpr auto operator"" q_t(long double l) { return mass<tonne, long double>(l); }
+constexpr auto operator"" _q_t(unsigned long long l) { return mass<tonne, std::int64_t>(l); }
+constexpr auto operator"" _q_t(long double l) { return mass<tonne, long double>(l); }
 
 // yt
-constexpr auto operator"" q_yt(unsigned long long l) { return mass<yoctotonne, std::int64_t>(l); }
-constexpr auto operator"" q_yt(long double l) { return mass<yoctotonne, long double>(l); }
+constexpr auto operator"" _q_yt(unsigned long long l) { return mass<yoctotonne, std::int64_t>(l); }
+constexpr auto operator"" _q_yt(long double l) { return mass<yoctotonne, long double>(l); }
 
 // zt
-constexpr auto operator"" q_zt(unsigned long long l) { return mass<zeptotonne, std::int64_t>(l); }
-constexpr auto operator"" q_zt(long double l) { return mass<zeptotonne, long double>(l); }
+constexpr auto operator"" _q_zt(unsigned long long l) { return mass<zeptotonne, std::int64_t>(l); }
+constexpr auto operator"" _q_zt(long double l) { return mass<zeptotonne, long double>(l); }
 
 // at
-constexpr auto operator"" q_at(unsigned long long l) { return mass<attotonne, std::int64_t>(l); }
-constexpr auto operator"" q_at(long double l) { return mass<attotonne, long double>(l); }
+constexpr auto operator"" _q_at(unsigned long long l) { return mass<attotonne, std::int64_t>(l); }
+constexpr auto operator"" _q_at(long double l) { return mass<attotonne, long double>(l); }
 
 // ft
-/*constexpr auto operator"" q_ft(unsigned long long l) { return mass<femtotonne, std::int64_t>(l); }
-constexpr auto operator"" q_ft(long double l) { return mass<femtotonne, long double>(l); }*/
+/*constexpr auto operator"" _q_ft(unsigned long long l) { return mass<femtotonne, std::int64_t>(l); }
+constexpr auto operator"" _q_ft(long double l) { return mass<femtotonne, long double>(l); }*/
 
 // pt
-constexpr auto operator"" q_pt(unsigned long long l) { return mass<picotonne, std::int64_t>(l); }
-constexpr auto operator"" q_pt(long double l) { return mass<picotonne, long double>(l); }
+constexpr auto operator"" _q_pt(unsigned long long l) { return mass<picotonne, std::int64_t>(l); }
+constexpr auto operator"" _q_pt(long double l) { return mass<picotonne, long double>(l); }
 
 // nt
-constexpr auto operator"" q_nt(unsigned long long l) { return mass<nanotonne, std::int64_t>(l); }
-constexpr auto operator"" q_nt(long double l) { return mass<nanotonne, long double>(l); }
+constexpr auto operator"" _q_nt(unsigned long long l) { return mass<nanotonne, std::int64_t>(l); }
+constexpr auto operator"" _q_nt(long double l) { return mass<nanotonne, long double>(l); }
 
 // ut
-constexpr auto operator"" q_ut(unsigned long long l) { return mass<microtonne, std::int64_t>(l); }
-constexpr auto operator"" q_ut(long double l) { return mass<microtonne, long double>(l); }
+constexpr auto operator"" _q_ut(unsigned long long l) { return mass<microtonne, std::int64_t>(l); }
+constexpr auto operator"" _q_ut(long double l) { return mass<microtonne, long double>(l); }
 
 // mt
-constexpr auto operator"" q_mt(unsigned long long l) { return mass<millitonne, std::int64_t>(l); }
-constexpr auto operator"" q_mt(long double l) { return mass<millitonne, long double>(l); }
+constexpr auto operator"" _q_mt(unsigned long long l) { return mass<millitonne, std::int64_t>(l); }
+constexpr auto operator"" _q_mt(long double l) { return mass<millitonne, long double>(l); }
 
 // ct
-constexpr auto operator"" q_ct(unsigned long long l) { return mass<centitonne, std::int64_t>(l); }
-constexpr auto operator"" q_ct(long double l) { return mass<centitonne, long double>(l); }
+constexpr auto operator"" _q_ct(unsigned long long l) { return mass<centitonne, std::int64_t>(l); }
+constexpr auto operator"" _q_ct(long double l) { return mass<centitonne, long double>(l); }
 
 // dt
-constexpr auto operator"" q_dt(unsigned long long l) { return mass<decitonne, std::int64_t>(l); }
-constexpr auto operator"" q_dt(long double l) { return mass<decitonne, long double>(l); }
+constexpr auto operator"" _q_dt(unsigned long long l) { return mass<decitonne, std::int64_t>(l); }
+constexpr auto operator"" _q_dt(long double l) { return mass<decitonne, long double>(l); }
 
 // dat
-constexpr auto operator"" q_dat(unsigned long long l) { return mass<decatonne, std::int64_t>(l); }
-constexpr auto operator"" q_dat(long double l) { return mass<decatonne, long double>(l); }
+constexpr auto operator"" _q_dat(unsigned long long l) { return mass<decatonne, std::int64_t>(l); }
+constexpr auto operator"" _q_dat(long double l) { return mass<decatonne, long double>(l); }
 
 // ht
-constexpr auto operator"" q_ht(unsigned long long l) { return mass<hectotonne, std::int64_t>(l); }
-constexpr auto operator"" q_ht(long double l) { return mass<hectotonne, long double>(l); }
+constexpr auto operator"" _q_ht(unsigned long long l) { return mass<hectotonne, std::int64_t>(l); }
+constexpr auto operator"" _q_ht(long double l) { return mass<hectotonne, long double>(l); }
 
 // kt
-constexpr auto operator"" q_kt(unsigned long long l) { return mass<kilotonne, std::int64_t>(l); }
-constexpr auto operator"" q_kt(long double l) { return mass<kilotonne, long double>(l); }
+constexpr auto operator"" _q_kt(unsigned long long l) { return mass<kilotonne, std::int64_t>(l); }
+constexpr auto operator"" _q_kt(long double l) { return mass<kilotonne, long double>(l); }
 
 // Mt
-constexpr auto operator"" q_Mt(unsigned long long l) { return mass<megatonne, std::int64_t>(l); }
-constexpr auto operator"" q_Mt(long double l) { return mass<megatonne, long double>(l); }
+constexpr auto operator"" _q_Mt(unsigned long long l) { return mass<megatonne, std::int64_t>(l); }
+constexpr auto operator"" _q_Mt(long double l) { return mass<megatonne, long double>(l); }
 
 // Gt
-constexpr auto operator"" q_Gt(unsigned long long l) { return mass<gigatonne, std::int64_t>(l); }
-constexpr auto operator"" q_Gt(long double l) { return mass<gigatonne, long double>(l); }
+constexpr auto operator"" _q_Gt(unsigned long long l) { return mass<gigatonne, std::int64_t>(l); }
+constexpr auto operator"" _q_Gt(long double l) { return mass<gigatonne, long double>(l); }
 
 // Tt
-constexpr auto operator"" q_Tt(unsigned long long l) { return mass<teratonne, std::int64_t>(l); }
-constexpr auto operator"" q_Tt(long double l) { return mass<teratonne, long double>(l); }
+constexpr auto operator"" _q_Tt(unsigned long long l) { return mass<teratonne, std::int64_t>(l); }
+constexpr auto operator"" _q_Tt(long double l) { return mass<teratonne, long double>(l); }
 
 // Pt
-constexpr auto operator"" q_Pt(unsigned long long l) { return mass<petatonne, std::int64_t>(l); }
-constexpr auto operator"" q_Pt(long double l) { return mass<petatonne, long double>(l); }
+constexpr auto operator"" _q_Pt(unsigned long long l) { return mass<petatonne, std::int64_t>(l); }
+constexpr auto operator"" _q_Pt(long double l) { return mass<petatonne, long double>(l); }
 
 // Et
-constexpr auto operator"" q_Et(unsigned long long l) { return mass<exatonne, std::int64_t>(l); }
-constexpr auto operator"" q_Et(long double l) { return mass<exatonne, long double>(l); }
+constexpr auto operator"" _q_Et(unsigned long long l) { return mass<exatonne, std::int64_t>(l); }
+constexpr auto operator"" _q_Et(long double l) { return mass<exatonne, long double>(l); }
 
 // Zt
-constexpr auto operator"" q_Zt(unsigned long long l) { return mass<zettatonne, std::int64_t>(l); }
-constexpr auto operator"" q_Zt(long double l) { return mass<zettatonne, long double>(l); }
+constexpr auto operator"" _q_Zt(unsigned long long l) { return mass<zettatonne, std::int64_t>(l); }
+constexpr auto operator"" _q_Zt(long double l) { return mass<zettatonne, long double>(l); }
 
 // Yt
-constexpr auto operator"" q_Yt(unsigned long long l) { return mass<yottatonne, std::int64_t>(l); }
-constexpr auto operator"" q_Yt(long double l) { return mass<yottatonne, long double>(l); }
+constexpr auto operator"" _q_Yt(unsigned long long l) { return mass<yottatonne, std::int64_t>(l); }
+constexpr auto operator"" _q_Yt(long double l) { return mass<yottatonne, long double>(l); }
 
 // Da
-constexpr auto operator"" q_Da(unsigned long long l) { return mass<dalton, std::int64_t>(l); }
-constexpr auto operator"" q_Da(long double l) { return mass<dalton, long double>(l); }
+constexpr auto operator"" _q_Da(unsigned long long l) { return mass<dalton, std::int64_t>(l); }
+constexpr auto operator"" _q_Da(long double l) { return mass<dalton, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/molar_energy.h b/src/include/units/physical/si/molar_energy.h
index cbfd44d6..3a3d8cd4 100644
--- a/src/include/units/physical/si/molar_energy.h
+++ b/src/include/units/physical/si/molar_energy.h
@@ -40,8 +40,8 @@ using molar_energy = quantity<dim_molar_energy, U, Rep>;
 inline namespace literals {
 
 // H/m
-constexpr auto operator"" q_J_per_mol(unsigned long long l) { return molar_energy<joule_per_mole, std::int64_t>(l); }
-constexpr auto operator"" q_J_per_mol(long double l) { return molar_energy<joule_per_mole, long double>(l); }
+constexpr auto operator"" _q_J_per_mol(unsigned long long l) { return molar_energy<joule_per_mole, std::int64_t>(l); }
+constexpr auto operator"" _q_J_per_mol(long double l) { return molar_energy<joule_per_mole, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/momentum.h b/src/include/units/physical/si/momentum.h
index f8f3d6da..b311ef60 100644
--- a/src/include/units/physical/si/momentum.h
+++ b/src/include/units/physical/si/momentum.h
@@ -38,8 +38,8 @@ using momentum = quantity<dim_momentum, U, Rep>;
 inline namespace literals {
 
 // kgmps
-constexpr auto operator"" q_kg_m_per_s(unsigned long long l) { return momentum<kilogram_metre_per_second, std::int64_t>(l); }
-constexpr auto operator"" q_kg_m_per_s(long double l) { return momentum<kilogram_metre_per_second, long double>(l); }
+constexpr auto operator"" _q_kg_m_per_s(unsigned long long l) { return momentum<kilogram_metre_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_kg_m_per_s(long double l) { return momentum<kilogram_metre_per_second, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/permeability.h b/src/include/units/physical/si/permeability.h
index a0bd9640..defc7715 100644
--- a/src/include/units/physical/si/permeability.h
+++ b/src/include/units/physical/si/permeability.h
@@ -39,8 +39,8 @@ using permeability = quantity<dim_permeability, U, Rep>;
 inline namespace literals {
 
 // H/m
-constexpr auto operator"" q_H_per_m(unsigned long long l) { return permeability<henry_per_metre, std::int64_t>(l); }
-constexpr auto operator"" q_H_per_m(long double l) { return permeability<henry_per_metre, long double>(l); }
+constexpr auto operator"" _q_H_per_m(unsigned long long l) { return permeability<henry_per_metre, std::int64_t>(l); }
+constexpr auto operator"" _q_H_per_m(long double l) { return permeability<henry_per_metre, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/permittivity.h b/src/include/units/physical/si/permittivity.h
index 151147ca..3d3a3239 100644
--- a/src/include/units/physical/si/permittivity.h
+++ b/src/include/units/physical/si/permittivity.h
@@ -39,8 +39,8 @@ using permittivity = quantity<dim_permittivity, U, Rep>;
 inline namespace literals {
 
 // F/m
-constexpr auto operator"" q_F_per_m(unsigned long long l) { return permittivity<farad_per_metre, std::int64_t>(l); }
-constexpr auto operator"" q_F_per_m(long double l) { return permittivity<farad_per_metre, long double>(l); }
+constexpr auto operator"" _q_F_per_m(unsigned long long l) { return permittivity<farad_per_metre, std::int64_t>(l); }
+constexpr auto operator"" _q_F_per_m(long double l) { return permittivity<farad_per_metre, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/power.h b/src/include/units/physical/si/power.h
index 42f62a02..def6ae9b 100644
--- a/src/include/units/physical/si/power.h
+++ b/src/include/units/physical/si/power.h
@@ -55,72 +55,72 @@ using power = quantity<dim_power, U, Rep>;
 inline namespace literals {
 
 // W
-constexpr auto operator"" q_W(unsigned long long l) { return power<watt, std::int64_t>(l); }
-constexpr auto operator"" q_W(long double l) { return power<watt, long double>(l); }
+constexpr auto operator"" _q_W(unsigned long long l) { return power<watt, std::int64_t>(l); }
+constexpr auto operator"" _q_W(long double l) { return power<watt, long double>(l); }
 
 // yW
-constexpr auto operator"" q_yW(unsigned long long l) { return power<yoctowatt, std::int64_t>(l); }
-constexpr auto operator"" q_yW(long double l) { return power<yoctowatt, long double>(l); }
+constexpr auto operator"" _q_yW(unsigned long long l) { return power<yoctowatt, std::int64_t>(l); }
+constexpr auto operator"" _q_yW(long double l) { return power<yoctowatt, long double>(l); }
 
 // zW
-constexpr auto operator"" q_zW(unsigned long long l) { return power<zeptowatt, std::int64_t>(l); }
-constexpr auto operator"" q_zW(long double l) { return power<zeptowatt, long double>(l); }
+constexpr auto operator"" _q_zW(unsigned long long l) { return power<zeptowatt, std::int64_t>(l); }
+constexpr auto operator"" _q_zW(long double l) { return power<zeptowatt, long double>(l); }
 
 // aW
-constexpr auto operator"" q_aW(unsigned long long l) { return power<attowatt, std::int64_t>(l); }
-constexpr auto operator"" q_aW(long double l) { return power<attowatt, long double>(l); }
+constexpr auto operator"" _q_aW(unsigned long long l) { return power<attowatt, std::int64_t>(l); }
+constexpr auto operator"" _q_aW(long double l) { return power<attowatt, long double>(l); }
 
 // fW
-constexpr auto operator"" q_fW(unsigned long long l) { return power<femtowatt, std::int64_t>(l); }
-constexpr auto operator"" q_fW(long double l) { return power<femtowatt, long double>(l); }
+constexpr auto operator"" _q_fW(unsigned long long l) { return power<femtowatt, std::int64_t>(l); }
+constexpr auto operator"" _q_fW(long double l) { return power<femtowatt, long double>(l); }
 
 // pW
-constexpr auto operator"" q_pW(unsigned long long l) { return power<picowatt, std::int64_t>(l); }
-constexpr auto operator"" q_pW(long double l) { return power<picowatt, long double>(l); }
+constexpr auto operator"" _q_pW(unsigned long long l) { return power<picowatt, std::int64_t>(l); }
+constexpr auto operator"" _q_pW(long double l) { return power<picowatt, long double>(l); }
 
 // nW
-constexpr auto operator"" q_nW(unsigned long long l) { return power<nanowatt, std::int64_t>(l); }
-constexpr auto operator"" q_nW(long double l) { return power<nanowatt, long double>(l); }
+constexpr auto operator"" _q_nW(unsigned long long l) { return power<nanowatt, std::int64_t>(l); }
+constexpr auto operator"" _q_nW(long double l) { return power<nanowatt, long double>(l); }
 
 // uW
-constexpr auto operator"" q_uW(unsigned long long l) { return power<microwatt, std::int64_t>(l); }
-constexpr auto operator"" q_uW(long double l) { return power<microwatt, long double>(l); }
+constexpr auto operator"" _q_uW(unsigned long long l) { return power<microwatt, std::int64_t>(l); }
+constexpr auto operator"" _q_uW(long double l) { return power<microwatt, long double>(l); }
 
 // mW
-constexpr auto operator"" q_mW(unsigned long long l) { return power<milliwatt, std::int64_t>(l); }
-constexpr auto operator"" q_mW(long double l) { return power<milliwatt, long double>(l); }
+constexpr auto operator"" _q_mW(unsigned long long l) { return power<milliwatt, std::int64_t>(l); }
+constexpr auto operator"" _q_mW(long double l) { return power<milliwatt, long double>(l); }
 
 // kW
-constexpr auto operator"" q_kW(unsigned long long l) { return power<kilowatt, std::int64_t>(l); }
-constexpr auto operator"" q_kW(long double l) { return power<kilowatt, long double>(l); }
+constexpr auto operator"" _q_kW(unsigned long long l) { return power<kilowatt, std::int64_t>(l); }
+constexpr auto operator"" _q_kW(long double l) { return power<kilowatt, long double>(l); }
 
 // MW
-constexpr auto operator"" q_MW(unsigned long long l) { return power<megawatt, std::int64_t>(l); }
-constexpr auto operator"" q_MW(long double l) { return power<megawatt, long double>(l); }
+constexpr auto operator"" _q_MW(unsigned long long l) { return power<megawatt, std::int64_t>(l); }
+constexpr auto operator"" _q_MW(long double l) { return power<megawatt, long double>(l); }
 
 // GW
-constexpr auto operator"" q_GW(unsigned long long l) { return power<gigawatt, std::int64_t>(l); }
-constexpr auto operator"" q_GW(long double l) { return power<gigawatt, long double>(l); }
+constexpr auto operator"" _q_GW(unsigned long long l) { return power<gigawatt, std::int64_t>(l); }
+constexpr auto operator"" _q_GW(long double l) { return power<gigawatt, long double>(l); }
 
 // TW
-constexpr auto operator"" q_TW(unsigned long long l) { return power<terawatt, std::int64_t>(l); }
-constexpr auto operator"" q_TW(long double l) { return power<terawatt, long double>(l); }
+constexpr auto operator"" _q_TW(unsigned long long l) { return power<terawatt, std::int64_t>(l); }
+constexpr auto operator"" _q_TW(long double l) { return power<terawatt, long double>(l); }
 
 // PW
-constexpr auto operator"" q_PW(unsigned long long l) { return power<petawatt, std::int64_t>(l); }
-constexpr auto operator"" q_PW(long double l) { return power<petawatt, long double>(l); }
+constexpr auto operator"" _q_PW(unsigned long long l) { return power<petawatt, std::int64_t>(l); }
+constexpr auto operator"" _q_PW(long double l) { return power<petawatt, long double>(l); }
 
 // EW
-constexpr auto operator"" q_EW(unsigned long long l) { return power<exawatt, std::int64_t>(l); }
-constexpr auto operator"" q_EW(long double l) { return power<exawatt, long double>(l); }
+constexpr auto operator"" _q_EW(unsigned long long l) { return power<exawatt, std::int64_t>(l); }
+constexpr auto operator"" _q_EW(long double l) { return power<exawatt, long double>(l); }
 
 // ZW
-constexpr auto operator"" q_ZW(unsigned long long l) { return power<zettawatt, std::int64_t>(l); }
-constexpr auto operator"" q_ZW(long double l) { return power<zettawatt, long double>(l); }
+constexpr auto operator"" _q_ZW(unsigned long long l) { return power<zettawatt, std::int64_t>(l); }
+constexpr auto operator"" _q_ZW(long double l) { return power<zettawatt, long double>(l); }
 
 // YW
-constexpr auto operator"" q_YW(unsigned long long l) { return power<yottawatt, std::int64_t>(l); }
-constexpr auto operator"" q_YW(long double l) { return power<yottawatt, long double>(l); }
+constexpr auto operator"" _q_YW(unsigned long long l) { return power<yottawatt, std::int64_t>(l); }
+constexpr auto operator"" _q_YW(long double l) { return power<yottawatt, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/pressure.h b/src/include/units/physical/si/pressure.h
index e0903d9d..a20d64c2 100644
--- a/src/include/units/physical/si/pressure.h
+++ b/src/include/units/physical/si/pressure.h
@@ -60,88 +60,88 @@ using pressure = quantity<dim_pressure, U, Rep>;
 inline namespace literals {
 
 // Pa
-constexpr auto operator"" q_Pa(unsigned long long l) { return pressure<pascal, std::int64_t>(l); }
-constexpr auto operator"" q_Pa(long double l) { return pressure<pascal, long double>(l); }
+constexpr auto operator"" _q_Pa(unsigned long long l) { return pressure<pascal, std::int64_t>(l); }
+constexpr auto operator"" _q_Pa(long double l) { return pressure<pascal, long double>(l); }
 
 // yPa
-constexpr auto operator"" q_yPa(unsigned long long l) { return pressure<yoctopascal, std::int64_t>(l); }
-constexpr auto operator"" q_yPa(long double l) { return pressure<yoctopascal, long double>(l); }
+constexpr auto operator"" _q_yPa(unsigned long long l) { return pressure<yoctopascal, std::int64_t>(l); }
+constexpr auto operator"" _q_yPa(long double l) { return pressure<yoctopascal, long double>(l); }
 
 // zPa
-constexpr auto operator"" q_zPa(unsigned long long l) { return pressure<zeptopascal, std::int64_t>(l); }
-constexpr auto operator"" q_zPa(long double l) { return pressure<zeptopascal, long double>(l); }
+constexpr auto operator"" _q_zPa(unsigned long long l) { return pressure<zeptopascal, std::int64_t>(l); }
+constexpr auto operator"" _q_zPa(long double l) { return pressure<zeptopascal, long double>(l); }
 
 // aPa
-constexpr auto operator"" q_aPa(unsigned long long l) { return pressure<attopascal, std::int64_t>(l); }
-constexpr auto operator"" q_aPa(long double l) { return pressure<attopascal, long double>(l); }
+constexpr auto operator"" _q_aPa(unsigned long long l) { return pressure<attopascal, std::int64_t>(l); }
+constexpr auto operator"" _q_aPa(long double l) { return pressure<attopascal, long double>(l); }
 
 // fPa
-constexpr auto operator"" q_fPa(unsigned long long l) { return pressure<femtopascal, std::int64_t>(l); }
-constexpr auto operator"" q_fPa(long double l) { return pressure<femtopascal, long double>(l); }
+constexpr auto operator"" _q_fPa(unsigned long long l) { return pressure<femtopascal, std::int64_t>(l); }
+constexpr auto operator"" _q_fPa(long double l) { return pressure<femtopascal, long double>(l); }
 
 // pPa
-constexpr auto operator"" q_pPa(unsigned long long l) { return pressure<picopascal, std::int64_t>(l); }
-constexpr auto operator"" q_pPa(long double l) { return pressure<picopascal, long double>(l); }
+constexpr auto operator"" _q_pPa(unsigned long long l) { return pressure<picopascal, std::int64_t>(l); }
+constexpr auto operator"" _q_pPa(long double l) { return pressure<picopascal, long double>(l); }
 
 // nPa
-constexpr auto operator"" q_nPa(unsigned long long l) { return pressure<nanopascal, std::int64_t>(l); }
-constexpr auto operator"" q_nPa(long double l) { return pressure<nanopascal, long double>(l); }
+constexpr auto operator"" _q_nPa(unsigned long long l) { return pressure<nanopascal, std::int64_t>(l); }
+constexpr auto operator"" _q_nPa(long double l) { return pressure<nanopascal, long double>(l); }
 
 // uPa
-constexpr auto operator"" q_uPa(unsigned long long l) { return pressure<micropascal, std::int64_t>(l); }
-constexpr auto operator"" q_uPa(long double l) { return pressure<micropascal, long double>(l); }
+constexpr auto operator"" _q_uPa(unsigned long long l) { return pressure<micropascal, std::int64_t>(l); }
+constexpr auto operator"" _q_uPa(long double l) { return pressure<micropascal, long double>(l); }
 
 // mPa
-constexpr auto operator"" q_mPa(unsigned long long l) { return pressure<millipascal, std::int64_t>(l); }
-constexpr auto operator"" q_mPa(long double l) { return pressure<millipascal, long double>(l); }
+constexpr auto operator"" _q_mPa(unsigned long long l) { return pressure<millipascal, std::int64_t>(l); }
+constexpr auto operator"" _q_mPa(long double l) { return pressure<millipascal, long double>(l); }
 
 // cPa
-constexpr auto operator"" q_cPa(unsigned long long l) { return pressure<centipascal, std::int64_t>(l); }
-constexpr auto operator"" q_cPa(long double l) { return pressure<centipascal, long double>(l); }
+constexpr auto operator"" _q_cPa(unsigned long long l) { return pressure<centipascal, std::int64_t>(l); }
+constexpr auto operator"" _q_cPa(long double l) { return pressure<centipascal, long double>(l); }
 
 // dPa
-constexpr auto operator"" q_dPa(unsigned long long l) { return pressure<decipascal, std::int64_t>(l); }
-constexpr auto operator"" q_dPa(long double l) { return pressure<decipascal, long double>(l); }
+constexpr auto operator"" _q_dPa(unsigned long long l) { return pressure<decipascal, std::int64_t>(l); }
+constexpr auto operator"" _q_dPa(long double l) { return pressure<decipascal, long double>(l); }
 
 // daPa
-constexpr auto operator"" q_daPa(unsigned long long l) { return pressure<decapascal, std::int64_t>(l); }
-constexpr auto operator"" q_daPa(long double l) { return pressure<decapascal, long double>(l); }
+constexpr auto operator"" _q_daPa(unsigned long long l) { return pressure<decapascal, std::int64_t>(l); }
+constexpr auto operator"" _q_daPa(long double l) { return pressure<decapascal, long double>(l); }
 
 // hPa
-constexpr auto operator"" q_hPa(unsigned long long l) { return pressure<hectopascal, std::int64_t>(l); }
-constexpr auto operator"" q_hPa(long double l) { return pressure<hectopascal, long double>(l); }
+constexpr auto operator"" _q_hPa(unsigned long long l) { return pressure<hectopascal, std::int64_t>(l); }
+constexpr auto operator"" _q_hPa(long double l) { return pressure<hectopascal, long double>(l); }
 
 // kPa
-constexpr auto operator"" q_kPa(unsigned long long l) { return pressure<kilopascal, std::int64_t>(l); }
-constexpr auto operator"" q_kPa(long double l) { return pressure<kilopascal, long double>(l); }
+constexpr auto operator"" _q_kPa(unsigned long long l) { return pressure<kilopascal, std::int64_t>(l); }
+constexpr auto operator"" _q_kPa(long double l) { return pressure<kilopascal, long double>(l); }
 
 // MPa
-constexpr auto operator"" q_MPa(unsigned long long l) { return pressure<megapascal, std::int64_t>(l); }
-constexpr auto operator"" q_MPa(long double l) { return pressure<megapascal, long double>(l); }
+constexpr auto operator"" _q_MPa(unsigned long long l) { return pressure<megapascal, std::int64_t>(l); }
+constexpr auto operator"" _q_MPa(long double l) { return pressure<megapascal, long double>(l); }
 
 // GPa
-constexpr auto operator"" q_GPa(unsigned long long l) { return pressure<gigapascal, std::int64_t>(l); }
-constexpr auto operator"" q_GPa(long double l) { return pressure<gigapascal, long double>(l); }
+constexpr auto operator"" _q_GPa(unsigned long long l) { return pressure<gigapascal, std::int64_t>(l); }
+constexpr auto operator"" _q_GPa(long double l) { return pressure<gigapascal, long double>(l); }
 
 // TPa
-constexpr auto operator"" q_TPa(unsigned long long l) { return pressure<terapascal, std::int64_t>(l); }
-constexpr auto operator"" q_TPa(long double l) { return pressure<terapascal, long double>(l); }
+constexpr auto operator"" _q_TPa(unsigned long long l) { return pressure<terapascal, std::int64_t>(l); }
+constexpr auto operator"" _q_TPa(long double l) { return pressure<terapascal, long double>(l); }
 
 // PPa
-constexpr auto operator"" q_PPa(unsigned long long l) { return pressure<petapascal, std::int64_t>(l); }
-constexpr auto operator"" q_PPa(long double l) { return pressure<petapascal, long double>(l); }
+constexpr auto operator"" _q_PPa(unsigned long long l) { return pressure<petapascal, std::int64_t>(l); }
+constexpr auto operator"" _q_PPa(long double l) { return pressure<petapascal, long double>(l); }
 
 // EPa
-constexpr auto operator"" q_EPa(unsigned long long l) { return pressure<exapascal, std::int64_t>(l); }
-constexpr auto operator"" q_EPa(long double l) { return pressure<exapascal, long double>(l); }
+constexpr auto operator"" _q_EPa(unsigned long long l) { return pressure<exapascal, std::int64_t>(l); }
+constexpr auto operator"" _q_EPa(long double l) { return pressure<exapascal, long double>(l); }
 
 // ZPa
-constexpr auto operator"" q_ZPa(unsigned long long l) { return pressure<zettapascal, std::int64_t>(l); }
-constexpr auto operator"" q_ZPa(long double l) { return pressure<zettapascal, long double>(l); }
+constexpr auto operator"" _q_ZPa(unsigned long long l) { return pressure<zettapascal, std::int64_t>(l); }
+constexpr auto operator"" _q_ZPa(long double l) { return pressure<zettapascal, long double>(l); }
 
 // YPa
-constexpr auto operator"" q_YPa(unsigned long long l) { return pressure<yottapascal, std::int64_t>(l); }
-constexpr auto operator"" q_YPa(long double l) { return pressure<yottapascal, long double>(l); }
+constexpr auto operator"" _q_YPa(unsigned long long l) { return pressure<yottapascal, std::int64_t>(l); }
+constexpr auto operator"" _q_YPa(long double l) { return pressure<yottapascal, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/resistance.h b/src/include/units/physical/si/resistance.h
index 4576b977..e857a845 100644
--- a/src/include/units/physical/si/resistance.h
+++ b/src/include/units/physical/si/resistance.h
@@ -56,72 +56,72 @@ using resistance = quantity<dim_resistance, U, Rep>;
 inline namespace literals {
 
 // R
-constexpr auto operator"" q_R(unsigned long long l) { return resistance<ohm, std::int64_t>(l); }
-constexpr auto operator"" q_R(long double l) { return resistance<ohm, long double>(l); }
+constexpr auto operator"" _q_R(unsigned long long l) { return resistance<ohm, std::int64_t>(l); }
+constexpr auto operator"" _q_R(long double l) { return resistance<ohm, long double>(l); }
 
 // yR
-constexpr auto operator"" q_yR(unsigned long long l) { return resistance<yoctoohm, std::int64_t>(l); }
-constexpr auto operator"" q_yR(long double l) { return resistance<yoctoohm, long double>(l); }
+constexpr auto operator"" _q_yR(unsigned long long l) { return resistance<yoctoohm, std::int64_t>(l); }
+constexpr auto operator"" _q_yR(long double l) { return resistance<yoctoohm, long double>(l); }
 
 // zR
-constexpr auto operator"" q_zR(unsigned long long l) { return resistance<zeptoohm, std::int64_t>(l); }
-constexpr auto operator"" q_zR(long double l) { return resistance<zeptoohm, long double>(l); }
+constexpr auto operator"" _q_zR(unsigned long long l) { return resistance<zeptoohm, std::int64_t>(l); }
+constexpr auto operator"" _q_zR(long double l) { return resistance<zeptoohm, long double>(l); }
 
 // aR
-constexpr auto operator"" q_aR(unsigned long long l) { return resistance<attoohm, std::int64_t>(l); }
-constexpr auto operator"" q_aR(long double l) { return resistance<attoohm, long double>(l); }
+constexpr auto operator"" _q_aR(unsigned long long l) { return resistance<attoohm, std::int64_t>(l); }
+constexpr auto operator"" _q_aR(long double l) { return resistance<attoohm, long double>(l); }
 
 // fR
-constexpr auto operator"" q_fR(unsigned long long l) { return resistance<femtoohm, std::int64_t>(l); }
-constexpr auto operator"" q_fR(long double l) { return resistance<femtoohm, long double>(l); }
+constexpr auto operator"" _q_fR(unsigned long long l) { return resistance<femtoohm, std::int64_t>(l); }
+constexpr auto operator"" _q_fR(long double l) { return resistance<femtoohm, long double>(l); }
 
 // pR
-constexpr auto operator"" q_pR(unsigned long long l) { return resistance<picoohm, std::int64_t>(l); }
-constexpr auto operator"" q_pR(long double l) { return resistance<picoohm, long double>(l); }
+constexpr auto operator"" _q_pR(unsigned long long l) { return resistance<picoohm, std::int64_t>(l); }
+constexpr auto operator"" _q_pR(long double l) { return resistance<picoohm, long double>(l); }
 
 // nR
-constexpr auto operator"" q_nR(unsigned long long l) { return resistance<nanoohm, std::int64_t>(l); }
-constexpr auto operator"" q_nR(long double l) { return resistance<nanoohm, long double>(l); }
+constexpr auto operator"" _q_nR(unsigned long long l) { return resistance<nanoohm, std::int64_t>(l); }
+constexpr auto operator"" _q_nR(long double l) { return resistance<nanoohm, long double>(l); }
 
 // uR
-constexpr auto operator"" q_uR(unsigned long long l) { return resistance<microohm, std::int64_t>(l); }
-constexpr auto operator"" q_uR(long double l) { return resistance<microohm, long double>(l); }
+constexpr auto operator"" _q_uR(unsigned long long l) { return resistance<microohm, std::int64_t>(l); }
+constexpr auto operator"" _q_uR(long double l) { return resistance<microohm, long double>(l); }
 
 // mR
-constexpr auto operator"" q_mR(unsigned long long l) { return resistance<milliohm, std::int64_t>(l); }
-constexpr auto operator"" q_mR(long double l) { return resistance<milliohm, long double>(l); }
+constexpr auto operator"" _q_mR(unsigned long long l) { return resistance<milliohm, std::int64_t>(l); }
+constexpr auto operator"" _q_mR(long double l) { return resistance<milliohm, long double>(l); }
 
 // kR
-constexpr auto operator"" q_kR(unsigned long long l) { return resistance<kiloohm, std::int64_t>(l); }
-constexpr auto operator"" q_kR(long double l) { return resistance<kiloohm, long double>(l); }
+constexpr auto operator"" _q_kR(unsigned long long l) { return resistance<kiloohm, std::int64_t>(l); }
+constexpr auto operator"" _q_kR(long double l) { return resistance<kiloohm, long double>(l); }
 
 // MR
-constexpr auto operator"" q_MR(unsigned long long l) { return resistance<megaohm, std::int64_t>(l); }
-constexpr auto operator"" q_MR(long double l) { return resistance<megaohm, long double>(l); }
+constexpr auto operator"" _q_MR(unsigned long long l) { return resistance<megaohm, std::int64_t>(l); }
+constexpr auto operator"" _q_MR(long double l) { return resistance<megaohm, long double>(l); }
 
 // GR
-constexpr auto operator"" q_GR(unsigned long long l) { return resistance<gigaohm, std::int64_t>(l); }
-constexpr auto operator"" q_GR(long double l) { return resistance<gigaohm, long double>(l); }
+constexpr auto operator"" _q_GR(unsigned long long l) { return resistance<gigaohm, std::int64_t>(l); }
+constexpr auto operator"" _q_GR(long double l) { return resistance<gigaohm, long double>(l); }
 
 // TR
-constexpr auto operator"" q_TR(unsigned long long l) { return resistance<teraohm, std::int64_t>(l); }
-constexpr auto operator"" q_TR(long double l) { return resistance<teraohm, long double>(l); }
+constexpr auto operator"" _q_TR(unsigned long long l) { return resistance<teraohm, std::int64_t>(l); }
+constexpr auto operator"" _q_TR(long double l) { return resistance<teraohm, long double>(l); }
 
 // PR
-constexpr auto operator"" q_PR(unsigned long long l) { return resistance<petaohm, std::int64_t>(l); }
-constexpr auto operator"" q_PR(long double l) { return resistance<petaohm, long double>(l); }
+constexpr auto operator"" _q_PR(unsigned long long l) { return resistance<petaohm, std::int64_t>(l); }
+constexpr auto operator"" _q_PR(long double l) { return resistance<petaohm, long double>(l); }
 
 // ER
-constexpr auto operator"" q_ER(unsigned long long l) { return resistance<exaohm, std::int64_t>(l); }
-constexpr auto operator"" q_ER(long double l) { return resistance<exaohm, long double>(l); }
+constexpr auto operator"" _q_ER(unsigned long long l) { return resistance<exaohm, std::int64_t>(l); }
+constexpr auto operator"" _q_ER(long double l) { return resistance<exaohm, long double>(l); }
 
 // ZR
-constexpr auto operator"" q_ZR(unsigned long long l) { return resistance<zettaohm, std::int64_t>(l); }
-constexpr auto operator"" q_ZR(long double l) { return resistance<zettaohm, long double>(l); }
+constexpr auto operator"" _q_ZR(unsigned long long l) { return resistance<zettaohm, std::int64_t>(l); }
+constexpr auto operator"" _q_ZR(long double l) { return resistance<zettaohm, long double>(l); }
 
 // YR
-constexpr auto operator"" q_YR(unsigned long long l) { return resistance<yottaohm, std::int64_t>(l); }
-constexpr auto operator"" q_YR(long double l) { return resistance<yottaohm, long double>(l); }
+constexpr auto operator"" _q_YR(unsigned long long l) { return resistance<yottaohm, std::int64_t>(l); }
+constexpr auto operator"" _q_YR(long double l) { return resistance<yottaohm, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/speed.h b/src/include/units/physical/si/speed.h
index 14f08186..d05af1bf 100644
--- a/src/include/units/physical/si/speed.h
+++ b/src/include/units/physical/si/speed.h
@@ -40,12 +40,12 @@ using speed = quantity<dim_speed, U, Rep>;
 inline namespace literals {
 
 // mps
-constexpr auto operator"" q_m_per_s(unsigned long long l) { return speed<metre_per_second, std::int64_t>(l); }
-constexpr auto operator"" q_m_per_s(long double l) { return speed<metre_per_second, long double>(l); }
+constexpr auto operator"" _q_m_per_s(unsigned long long l) { return speed<metre_per_second, std::int64_t>(l); }
+constexpr auto operator"" _q_m_per_s(long double l) { return speed<metre_per_second, long double>(l); }
 
 // kmph
-constexpr auto operator"" q_km_per_h(unsigned long long l) { return speed<kilometre_per_hour, std::int64_t>(l); }
-constexpr auto operator"" q_km_per_h(long double l) { return speed<kilometre_per_hour, long double>(l); }
+constexpr auto operator"" _q_km_per_h(unsigned long long l) { return speed<kilometre_per_hour, std::int64_t>(l); }
+constexpr auto operator"" _q_km_per_h(long double l) { return speed<kilometre_per_hour, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/substance.h b/src/include/units/physical/si/substance.h
index c7706edc..4c3c5a5a 100644
--- a/src/include/units/physical/si/substance.h
+++ b/src/include/units/physical/si/substance.h
@@ -38,8 +38,8 @@ using substance = quantity<dim_substance, U, Rep>;
 inline namespace literals {
 
 // mol
-constexpr auto operator"" q_mol(unsigned long long l) { return substance<mole, std::int64_t>(l); }
-constexpr auto operator"" q_mol(long double l) { return substance<mole, long double>(l); }
+constexpr auto operator"" _q_mol(unsigned long long l) { return substance<mole, std::int64_t>(l); }
+constexpr auto operator"" _q_mol(long double l) { return substance<mole, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/surface_tension.h b/src/include/units/physical/si/surface_tension.h
index 67867061..1b20f461 100644
--- a/src/include/units/physical/si/surface_tension.h
+++ b/src/include/units/physical/si/surface_tension.h
@@ -38,8 +38,8 @@ using surface_tension = quantity<dim_surface_tension, U, Rep>;
 inline namespace literals {
 
   // Nm
-  constexpr auto operator"" q_N_per_m(unsigned long long l) { return surface_tension<newton_per_metre, std::int64_t>(l); }
-  constexpr auto operator"" q_N_per_m(long double l) { return surface_tension<newton_per_metre, long double>(l); }
+  constexpr auto operator"" _q_N_per_m(unsigned long long l) { return surface_tension<newton_per_metre, std::int64_t>(l); }
+  constexpr auto operator"" _q_N_per_m(long double l) { return surface_tension<newton_per_metre, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/temperature.h b/src/include/units/physical/si/temperature.h
index 19fc2ddb..c52fd838 100644
--- a/src/include/units/physical/si/temperature.h
+++ b/src/include/units/physical/si/temperature.h
@@ -37,8 +37,8 @@ using temperature = quantity<dim_thermodynamic_temperature, U, Rep>;
 inline namespace literals {
 
 // K
-constexpr auto operator"" q_K(unsigned long long l) { return temperature<kelvin, std::int64_t>(l); }
-constexpr auto operator"" q_K(long double l) { return temperature<kelvin, long double>(l); }
+constexpr auto operator"" _q_K(unsigned long long l) { return temperature<kelvin, std::int64_t>(l); }
+constexpr auto operator"" _q_K(long double l) { return temperature<kelvin, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/thermal_conductivity.h b/src/include/units/physical/si/thermal_conductivity.h
index ff845792..8b20b744 100644
--- a/src/include/units/physical/si/thermal_conductivity.h
+++ b/src/include/units/physical/si/thermal_conductivity.h
@@ -39,8 +39,8 @@ using thermal_conductivity = quantity<dim_thermal_conductivity, U, Rep>;
 inline namespace literals {
 
 // J/K
-constexpr auto operator"" q_W_per_m_K(unsigned long long l) { return thermal_conductivity<watt_per_metre_kelvin, std::int64_t>(l); }
-constexpr auto operator"" q_W_per_m_K(long double l) { return thermal_conductivity<watt_per_metre_kelvin, long double>(l); }
+constexpr auto operator"" _q_W_per_m_K(unsigned long long l) { return thermal_conductivity<watt_per_metre_kelvin, std::int64_t>(l); }
+constexpr auto operator"" _q_W_per_m_K(long double l) { return thermal_conductivity<watt_per_metre_kelvin, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/time.h b/src/include/units/physical/si/time.h
index f3352295..c6c37359 100644
--- a/src/include/units/physical/si/time.h
+++ b/src/include/units/physical/si/time.h
@@ -49,52 +49,52 @@ using time = quantity<dim_time, U, Rep>;
 inline namespace literals {
 
 // ys
-constexpr auto operator"" q_ys(unsigned long long l) { return time<yoctosecond, std::int64_t>(l); }
-constexpr auto operator"" q_ys(long double l) { return time<yoctosecond, long double>(l); }
+constexpr auto operator"" _q_ys(unsigned long long l) { return time<yoctosecond, std::int64_t>(l); }
+constexpr auto operator"" _q_ys(long double l) { return time<yoctosecond, long double>(l); }
 
 // zs
-constexpr auto operator"" q_zs(unsigned long long l) { return time<zeptosecond, std::int64_t>(l); }
-constexpr auto operator"" q_zs(long double l) { return time<zeptosecond, long double>(l); }
+constexpr auto operator"" _q_zs(unsigned long long l) { return time<zeptosecond, std::int64_t>(l); }
+constexpr auto operator"" _q_zs(long double l) { return time<zeptosecond, long double>(l); }
 
 // as
-constexpr auto operator"" q_as(unsigned long long l) { return time<attosecond, std::int64_t>(l); }
-constexpr auto operator"" q_as(long double l) { return time<attosecond, long double>(l); }
+constexpr auto operator"" _q_as(unsigned long long l) { return time<attosecond, std::int64_t>(l); }
+constexpr auto operator"" _q_as(long double l) { return time<attosecond, long double>(l); }
 
 // fs
-constexpr auto operator"" q_fs(unsigned long long l) { return time<femtosecond, std::int64_t>(l); }
-constexpr auto operator"" q_fs(long double l) { return time<femtosecond, long double>(l); }
+constexpr auto operator"" _q_fs(unsigned long long l) { return time<femtosecond, std::int64_t>(l); }
+constexpr auto operator"" _q_fs(long double l) { return time<femtosecond, long double>(l); }
 
 // ps
-constexpr auto operator"" q_ps(unsigned long long l) { return time<picosecond, std::int64_t>(l); }
-constexpr auto operator"" q_ps(long double l) { return time<picosecond, long double>(l); }
+constexpr auto operator"" _q_ps(unsigned long long l) { return time<picosecond, std::int64_t>(l); }
+constexpr auto operator"" _q_ps(long double l) { return time<picosecond, long double>(l); }
 
 // ns
-constexpr auto operator"" q_ns(unsigned long long l) { return time<nanosecond, std::int64_t>(l); }
-constexpr auto operator"" q_ns(long double l) { return time<nanosecond, long double>(l); }
+constexpr auto operator"" _q_ns(unsigned long long l) { return time<nanosecond, std::int64_t>(l); }
+constexpr auto operator"" _q_ns(long double l) { return time<nanosecond, long double>(l); }
 
 // us
-constexpr auto operator"" q_us(unsigned long long l) { return time<microsecond, std::int64_t>(l); }
-constexpr auto operator"" q_us(long double l) { return time<microsecond, long double>(l); }
+constexpr auto operator"" _q_us(unsigned long long l) { return time<microsecond, std::int64_t>(l); }
+constexpr auto operator"" _q_us(long double l) { return time<microsecond, long double>(l); }
 
 // ms
-constexpr auto operator"" q_ms(unsigned long long l) { return time<millisecond, std::int64_t>(l); }
-constexpr auto operator"" q_ms(long double l) { return time<millisecond, long double>(l); }
+constexpr auto operator"" _q_ms(unsigned long long l) { return time<millisecond, std::int64_t>(l); }
+constexpr auto operator"" _q_ms(long double l) { return time<millisecond, long double>(l); }
 
 // s
-constexpr auto operator"" q_s(unsigned long long l) { return time<second, std::int64_t>(l); }
-constexpr auto operator"" q_s(long double l) { return time<second, long double>(l); }
+constexpr auto operator"" _q_s(unsigned long long l) { return time<second, std::int64_t>(l); }
+constexpr auto operator"" _q_s(long double l) { return time<second, long double>(l); }
 
 // min
-constexpr auto operator"" q_min(unsigned long long l) { return time<minute, std::int64_t>(l); }
-constexpr auto operator"" q_min(long double l) { return time<minute, long double>(l); }
+constexpr auto operator"" _q_min(unsigned long long l) { return time<minute, std::int64_t>(l); }
+constexpr auto operator"" _q_min(long double l) { return time<minute, long double>(l); }
 
 // h
-constexpr auto operator"" q_h(unsigned long long l) { return time<hour, std::int64_t>(l); }
-constexpr auto operator"" q_h(long double l) { return time<hour, long double>(l); }
+constexpr auto operator"" _q_h(unsigned long long l) { return time<hour, std::int64_t>(l); }
+constexpr auto operator"" _q_h(long double l) { return time<hour, long double>(l); }
 
 // d
-constexpr auto operator"" q_d(unsigned long long l) { return time<day, std::int64_t>(l); }
-constexpr auto operator"" q_d(long double l) { return time<day, long double>(l); }
+constexpr auto operator"" _q_d(unsigned long long l) { return time<day, std::int64_t>(l); }
+constexpr auto operator"" _q_d(long double l) { return time<day, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/torque.h b/src/include/units/physical/si/torque.h
index e5aee85d..1792889a 100644
--- a/src/include/units/physical/si/torque.h
+++ b/src/include/units/physical/si/torque.h
@@ -40,8 +40,8 @@ using torque = quantity<dim_torque, U, Rep>;
 inline namespace literals {
 
 // Nm
-constexpr auto operator"" q_Nm(unsigned long long l) { return torque<newton_metre, std::int64_t>(l); }
-constexpr auto operator"" q_Nm(long double l) { return torque<newton_metre, long double>(l); }
+constexpr auto operator"" _q_Nm(unsigned long long l) { return torque<newton_metre, std::int64_t>(l); }
+constexpr auto operator"" _q_Nm(long double l) { return torque<newton_metre, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/voltage.h b/src/include/units/physical/si/voltage.h
index a0e9ee7a..3d6eba9a 100644
--- a/src/include/units/physical/si/voltage.h
+++ b/src/include/units/physical/si/voltage.h
@@ -60,88 +60,88 @@ using voltage = quantity<dim_voltage, U, Rep>;
 inline namespace literals {
 
 // V
-constexpr auto operator"" q_V(unsigned long long l) { return voltage<volt, std::int64_t>(l); }
-constexpr auto operator"" q_V(long double l) { return voltage<volt, long double>(l); }
+constexpr auto operator"" _q_V(unsigned long long l) { return voltage<volt, std::int64_t>(l); }
+constexpr auto operator"" _q_V(long double l) { return voltage<volt, long double>(l); }
 
 // yV
-constexpr auto operator"" q_yV(unsigned long long l) { return voltage<yoctovolt, std::int64_t>(l); }
-constexpr auto operator"" q_yV(long double l) { return voltage<yoctovolt, long double>(l); }
+constexpr auto operator"" _q_yV(unsigned long long l) { return voltage<yoctovolt, std::int64_t>(l); }
+constexpr auto operator"" _q_yV(long double l) { return voltage<yoctovolt, long double>(l); }
 
 // zV
-constexpr auto operator"" q_zV(unsigned long long l) { return voltage<zeptovolt, std::int64_t>(l); }
-constexpr auto operator"" q_zV(long double l) { return voltage<zeptovolt, long double>(l); }
+constexpr auto operator"" _q_zV(unsigned long long l) { return voltage<zeptovolt, std::int64_t>(l); }
+constexpr auto operator"" _q_zV(long double l) { return voltage<zeptovolt, long double>(l); }
 
 // aV
-constexpr auto operator"" q_aV(unsigned long long l) { return voltage<attovolt, std::int64_t>(l); }
-constexpr auto operator"" q_aV(long double l) { return voltage<attovolt, long double>(l); }
+constexpr auto operator"" _q_aV(unsigned long long l) { return voltage<attovolt, std::int64_t>(l); }
+constexpr auto operator"" _q_aV(long double l) { return voltage<attovolt, long double>(l); }
 
 // fV
-constexpr auto operator"" q_fV(unsigned long long l) { return voltage<femtovolt, std::int64_t>(l); }
-constexpr auto operator"" q_fV(long double l) { return voltage<femtovolt, long double>(l); }
+constexpr auto operator"" _q_fV(unsigned long long l) { return voltage<femtovolt, std::int64_t>(l); }
+constexpr auto operator"" _q_fV(long double l) { return voltage<femtovolt, long double>(l); }
 
 // pV
-constexpr auto operator"" q_pV(unsigned long long l) { return voltage<picovolt, std::int64_t>(l); }
-constexpr auto operator"" q_pV(long double l) { return voltage<picovolt, long double>(l); }
+constexpr auto operator"" _q_pV(unsigned long long l) { return voltage<picovolt, std::int64_t>(l); }
+constexpr auto operator"" _q_pV(long double l) { return voltage<picovolt, long double>(l); }
 
 // nV
-constexpr auto operator"" q_nV(unsigned long long l) { return voltage<nanovolt, std::int64_t>(l); }
-constexpr auto operator"" q_nV(long double l) { return voltage<nanovolt, long double>(l); }
+constexpr auto operator"" _q_nV(unsigned long long l) { return voltage<nanovolt, std::int64_t>(l); }
+constexpr auto operator"" _q_nV(long double l) { return voltage<nanovolt, long double>(l); }
 
 // uV
-constexpr auto operator"" q_uV(unsigned long long l) { return voltage<microvolt, std::int64_t>(l); }
-constexpr auto operator"" q_uV(long double l) { return voltage<microvolt, long double>(l); }
+constexpr auto operator"" _q_uV(unsigned long long l) { return voltage<microvolt, std::int64_t>(l); }
+constexpr auto operator"" _q_uV(long double l) { return voltage<microvolt, long double>(l); }
 
 // mV
-constexpr auto operator"" q_mV(unsigned long long l) { return voltage<millivolt, std::int64_t>(l); }
-constexpr auto operator"" q_mV(long double l) { return voltage<millivolt, long double>(l); }
+constexpr auto operator"" _q_mV(unsigned long long l) { return voltage<millivolt, std::int64_t>(l); }
+constexpr auto operator"" _q_mV(long double l) { return voltage<millivolt, long double>(l); }
 
 // cV
-constexpr auto operator"" q_cV(unsigned long long l) { return voltage<centivolt, std::int64_t>(l); }
-constexpr auto operator"" q_cV(long double l) { return voltage<centivolt, long double>(l); }
+constexpr auto operator"" _q_cV(unsigned long long l) { return voltage<centivolt, std::int64_t>(l); }
+constexpr auto operator"" _q_cV(long double l) { return voltage<centivolt, long double>(l); }
 
 // dV
-constexpr auto operator"" q_dV(unsigned long long l) { return voltage<decivolt, std::int64_t>(l); }
-constexpr auto operator"" q_dV(long double l) { return voltage<decivolt, long double>(l); }
+constexpr auto operator"" _q_dV(unsigned long long l) { return voltage<decivolt, std::int64_t>(l); }
+constexpr auto operator"" _q_dV(long double l) { return voltage<decivolt, long double>(l); }
 
 // daV
-constexpr auto operator"" q_daV(unsigned long long l) { return voltage<decavolt, std::int64_t>(l); }
-constexpr auto operator"" q_daV(long double l) { return voltage<decavolt, long double>(l); }
+constexpr auto operator"" _q_daV(unsigned long long l) { return voltage<decavolt, std::int64_t>(l); }
+constexpr auto operator"" _q_daV(long double l) { return voltage<decavolt, long double>(l); }
 
 // hV
-constexpr auto operator"" q_hV(unsigned long long l) { return voltage<hectovolt, std::int64_t>(l); }
-constexpr auto operator"" q_hV(long double l) { return voltage<hectovolt, long double>(l); }
+constexpr auto operator"" _q_hV(unsigned long long l) { return voltage<hectovolt, std::int64_t>(l); }
+constexpr auto operator"" _q_hV(long double l) { return voltage<hectovolt, long double>(l); }
 
 // kV
-constexpr auto operator"" q_kV(unsigned long long l) { return voltage<kilovolt, std::int64_t>(l); }
-constexpr auto operator"" q_kV(long double l) { return voltage<kilovolt, long double>(l); }
+constexpr auto operator"" _q_kV(unsigned long long l) { return voltage<kilovolt, std::int64_t>(l); }
+constexpr auto operator"" _q_kV(long double l) { return voltage<kilovolt, long double>(l); }
 
 // MV
-constexpr auto operator"" q_MV(unsigned long long l) { return voltage<megavolt, std::int64_t>(l); }
-constexpr auto operator"" q_MV(long double l) { return voltage<megavolt, long double>(l); }
+constexpr auto operator"" _q_MV(unsigned long long l) { return voltage<megavolt, std::int64_t>(l); }
+constexpr auto operator"" _q_MV(long double l) { return voltage<megavolt, long double>(l); }
 
 // GV
-constexpr auto operator"" q_GV(unsigned long long l) { return voltage<gigavolt, std::int64_t>(l); }
-constexpr auto operator"" q_GV(long double l) { return voltage<gigavolt, long double>(l); }
+constexpr auto operator"" _q_GV(unsigned long long l) { return voltage<gigavolt, std::int64_t>(l); }
+constexpr auto operator"" _q_GV(long double l) { return voltage<gigavolt, long double>(l); }
 
 // TV
-constexpr auto operator"" q_TV(unsigned long long l) { return voltage<teravolt, std::int64_t>(l); }
-constexpr auto operator"" q_TV(long double l) { return voltage<teravolt, long double>(l); }
+constexpr auto operator"" _q_TV(unsigned long long l) { return voltage<teravolt, std::int64_t>(l); }
+constexpr auto operator"" _q_TV(long double l) { return voltage<teravolt, long double>(l); }
 
 // PV
-constexpr auto operator"" q_PV(unsigned long long l) { return voltage<petavolt, std::int64_t>(l); }
-constexpr auto operator"" q_PV(long double l) { return voltage<petavolt, long double>(l); }
+constexpr auto operator"" _q_PV(unsigned long long l) { return voltage<petavolt, std::int64_t>(l); }
+constexpr auto operator"" _q_PV(long double l) { return voltage<petavolt, long double>(l); }
 
 // EV
-constexpr auto operator"" q_EV(unsigned long long l) { return voltage<exavolt, std::int64_t>(l); }
-constexpr auto operator"" q_EV(long double l) { return voltage<exavolt, long double>(l); }
+constexpr auto operator"" _q_EV(unsigned long long l) { return voltage<exavolt, std::int64_t>(l); }
+constexpr auto operator"" _q_EV(long double l) { return voltage<exavolt, long double>(l); }
 
 // ZV
-constexpr auto operator"" q_ZV(unsigned long long l) { return voltage<zettavolt, std::int64_t>(l); }
-constexpr auto operator"" q_ZV(long double l) { return voltage<zettavolt, long double>(l); }
+constexpr auto operator"" _q_ZV(unsigned long long l) { return voltage<zettavolt, std::int64_t>(l); }
+constexpr auto operator"" _q_ZV(long double l) { return voltage<zettavolt, long double>(l); }
 
 // YV
-constexpr auto operator"" q_YV(unsigned long long l) { return voltage<yottavolt, std::int64_t>(l); }
-constexpr auto operator"" q_YV(long double l) { return voltage<yottavolt, long double>(l); }
+constexpr auto operator"" _q_YV(unsigned long long l) { return voltage<yottavolt, std::int64_t>(l); }
+constexpr auto operator"" _q_YV(long double l) { return voltage<yottavolt, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/si/volume.h b/src/include/units/physical/si/volume.h
index 6d60139c..7490a56b 100644
--- a/src/include/units/physical/si/volume.h
+++ b/src/include/units/physical/si/volume.h
@@ -80,172 +80,172 @@ using volume = quantity<dim_volume, U, Rep>;
 inline namespace literals {
 
 // m3
-constexpr auto operator"" q_m3(unsigned long long l) { return volume<cubic_metre, std::int64_t>(l); }
-constexpr auto operator"" q_m3(long double l) { return volume<cubic_metre, long double>(l); }
+constexpr auto operator"" _q_m3(unsigned long long l) { return volume<cubic_metre, std::int64_t>(l); }
+constexpr auto operator"" _q_m3(long double l) { return volume<cubic_metre, long double>(l); }
 
 // ym3
-constexpr auto operator"" q_ym3(unsigned long long l) { return volume<cubic_yoctometre, std::int64_t>(l); }
-constexpr auto operator"" q_ym3(long double l) { return volume<cubic_yoctometre, long double>(l); }
+constexpr auto operator"" _q_ym3(unsigned long long l) { return volume<cubic_yoctometre, std::int64_t>(l); }
+constexpr auto operator"" _q_ym3(long double l) { return volume<cubic_yoctometre, long double>(l); }
 
 // zm3
-constexpr auto operator"" q_zm3(unsigned long long l) { return volume<cubic_zeptometre, std::int64_t>(l); }
-constexpr auto operator"" q_zm3(long double l) { return volume<cubic_zeptometre, long double>(l); }
+constexpr auto operator"" _q_zm3(unsigned long long l) { return volume<cubic_zeptometre, std::int64_t>(l); }
+constexpr auto operator"" _q_zm3(long double l) { return volume<cubic_zeptometre, long double>(l); }
 
 // am3
-constexpr auto operator"" q_am3(unsigned long long l) { return volume<cubic_attometre, std::int64_t>(l); }
-constexpr auto operator"" q_am3(long double l) { return volume<cubic_attometre, long double>(l); }
+constexpr auto operator"" _q_am3(unsigned long long l) { return volume<cubic_attometre, std::int64_t>(l); }
+constexpr auto operator"" _q_am3(long double l) { return volume<cubic_attometre, long double>(l); }
 
 // fm3
-constexpr auto operator"" q_fm3(unsigned long long l) { return volume<cubic_femtometre, std::int64_t>(l); }
-constexpr auto operator"" q_fm3(long double l) { return volume<cubic_femtometre, long double>(l); }
+constexpr auto operator"" _q_fm3(unsigned long long l) { return volume<cubic_femtometre, std::int64_t>(l); }
+constexpr auto operator"" _q_fm3(long double l) { return volume<cubic_femtometre, long double>(l); }
 
 // pm3
-constexpr auto operator"" q_pm3(unsigned long long l) { return volume<cubic_picometre, std::int64_t>(l); }
-constexpr auto operator"" q_pm3(long double l) { return volume<cubic_picometre, long double>(l); }
+constexpr auto operator"" _q_pm3(unsigned long long l) { return volume<cubic_picometre, std::int64_t>(l); }
+constexpr auto operator"" _q_pm3(long double l) { return volume<cubic_picometre, long double>(l); }
 
 // nm3
-constexpr auto operator"" q_nm3(unsigned long long l) { return volume<cubic_nanometre, std::int64_t>(l); }
-constexpr auto operator"" q_nm3(long double l) { return volume<cubic_nanometre, long double>(l); }
+constexpr auto operator"" _q_nm3(unsigned long long l) { return volume<cubic_nanometre, std::int64_t>(l); }
+constexpr auto operator"" _q_nm3(long double l) { return volume<cubic_nanometre, long double>(l); }
 
 // um3
-constexpr auto operator"" q_um3(unsigned long long l) { return volume<cubic_micrometre, std::int64_t>(l); }
-constexpr auto operator"" q_um3(long double l) { return volume<cubic_micrometre, long double>(l); }
+constexpr auto operator"" _q_um3(unsigned long long l) { return volume<cubic_micrometre, std::int64_t>(l); }
+constexpr auto operator"" _q_um3(long double l) { return volume<cubic_micrometre, long double>(l); }
 
 // mm3
-constexpr auto operator"" q_mm3(unsigned long long l) { return volume<cubic_millimetre, std::int64_t>(l); }
-constexpr auto operator"" q_mm3(long double l) { return volume<cubic_millimetre, long double>(l); }
+constexpr auto operator"" _q_mm3(unsigned long long l) { return volume<cubic_millimetre, std::int64_t>(l); }
+constexpr auto operator"" _q_mm3(long double l) { return volume<cubic_millimetre, long double>(l); }
 
 // cm3
-constexpr auto operator"" q_cm3(unsigned long long l) { return volume<cubic_centimetre, std::int64_t>(l); }
-constexpr auto operator"" q_cm3(long double l) { return volume<cubic_centimetre, long double>(l); }
+constexpr auto operator"" _q_cm3(unsigned long long l) { return volume<cubic_centimetre, std::int64_t>(l); }
+constexpr auto operator"" _q_cm3(long double l) { return volume<cubic_centimetre, long double>(l); }
 
 // dm3
-constexpr auto operator"" q_dm3(unsigned long long l) { return volume<cubic_decimetre, std::int64_t>(l); }
-constexpr auto operator"" q_dm3(long double l) { return volume<cubic_decimetre, long double>(l); }
+constexpr auto operator"" _q_dm3(unsigned long long l) { return volume<cubic_decimetre, std::int64_t>(l); }
+constexpr auto operator"" _q_dm3(long double l) { return volume<cubic_decimetre, long double>(l); }
 
 // dam3
-constexpr auto operator"" q_dam3(unsigned long long l) { return volume<cubic_decametre, std::int64_t>(l); }
-constexpr auto operator"" q_dam3(long double l) { return volume<cubic_decametre, long double>(l); }
+constexpr auto operator"" _q_dam3(unsigned long long l) { return volume<cubic_decametre, std::int64_t>(l); }
+constexpr auto operator"" _q_dam3(long double l) { return volume<cubic_decametre, long double>(l); }
 
 // hm3
-constexpr auto operator"" q_hm3(unsigned long long l) { return volume<cubic_hectometre, std::int64_t>(l); }
-constexpr auto operator"" q_hm3(long double l) { return volume<cubic_hectometre, long double>(l); }
+constexpr auto operator"" _q_hm3(unsigned long long l) { return volume<cubic_hectometre, std::int64_t>(l); }
+constexpr auto operator"" _q_hm3(long double l) { return volume<cubic_hectometre, long double>(l); }
 
 // km3
-constexpr auto operator"" q_km3(unsigned long long l) { return volume<cubic_kilometre, std::int64_t>(l); }
-constexpr auto operator"" q_km3(long double l) { return volume<cubic_kilometre, long double>(l); }
+constexpr auto operator"" _q_km3(unsigned long long l) { return volume<cubic_kilometre, std::int64_t>(l); }
+constexpr auto operator"" _q_km3(long double l) { return volume<cubic_kilometre, long double>(l); }
 
 // Mm3
-constexpr auto operator"" q_Mm3(unsigned long long l) { return volume<cubic_megametre, std::int64_t>(l); }
-constexpr auto operator"" q_Mm3(long double l) { return volume<cubic_megametre, long double>(l); }
+constexpr auto operator"" _q_Mm3(unsigned long long l) { return volume<cubic_megametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Mm3(long double l) { return volume<cubic_megametre, long double>(l); }
 
 // Gm3
-constexpr auto operator"" q_Gm3(unsigned long long l) { return volume<cubic_gigametre, std::int64_t>(l); }
-constexpr auto operator"" q_Gm3(long double l) { return volume<cubic_gigametre, long double>(l); }
+constexpr auto operator"" _q_Gm3(unsigned long long l) { return volume<cubic_gigametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Gm3(long double l) { return volume<cubic_gigametre, long double>(l); }
 
 // Tm3
-constexpr auto operator"" q_Tm3(unsigned long long l) { return volume<cubic_terametre, std::int64_t>(l); }
-constexpr auto operator"" q_Tm3(long double l) { return volume<cubic_terametre, long double>(l); }
+constexpr auto operator"" _q_Tm3(unsigned long long l) { return volume<cubic_terametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Tm3(long double l) { return volume<cubic_terametre, long double>(l); }
 
 // Pm3
-constexpr auto operator"" q_Pm3(unsigned long long l) { return volume<cubic_petametre, std::int64_t>(l); }
-constexpr auto operator"" q_Pm3(long double l) { return volume<cubic_petametre, long double>(l); }
+constexpr auto operator"" _q_Pm3(unsigned long long l) { return volume<cubic_petametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Pm3(long double l) { return volume<cubic_petametre, long double>(l); }
 
 // Em3
-constexpr auto operator"" q_Em3(unsigned long long l) { return volume<cubic_exametre, std::int64_t>(l); }
-constexpr auto operator"" q_Em3(long double l) { return volume<cubic_exametre, long double>(l); }
+constexpr auto operator"" _q_Em3(unsigned long long l) { return volume<cubic_exametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Em3(long double l) { return volume<cubic_exametre, long double>(l); }
 
 // Zm3
-constexpr auto operator"" q_Zm3(unsigned long long l) { return volume<cubic_zettametre, std::int64_t>(l); }
-constexpr auto operator"" q_Zm3(long double l) { return volume<cubic_zettametre, long double>(l); }
+constexpr auto operator"" _q_Zm3(unsigned long long l) { return volume<cubic_zettametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Zm3(long double l) { return volume<cubic_zettametre, long double>(l); }
 
 // Ym3
-constexpr auto operator"" q_Ym3(unsigned long long l) { return volume<cubic_yottametre, std::int64_t>(l); }
-constexpr auto operator"" q_Ym3(long double l) { return volume<cubic_yottametre, long double>(l); }
+constexpr auto operator"" _q_Ym3(unsigned long long l) { return volume<cubic_yottametre, std::int64_t>(l); }
+constexpr auto operator"" _q_Ym3(long double l) { return volume<cubic_yottametre, long double>(l); }
 
 // l
-constexpr auto operator"" q_l(unsigned long long l) { return volume<litre, std::int64_t>(l); }
-constexpr auto operator"" q_l(long double l) { return volume<litre, long double>(l); }
+constexpr auto operator"" _q_l(unsigned long long l) { return volume<litre, std::int64_t>(l); }
+constexpr auto operator"" _q_l(long double l) { return volume<litre, long double>(l); }
 
 // yl
-constexpr auto operator"" q_yl(unsigned long long l) { return volume<yoctolitre, std::int64_t>(l); }
-constexpr auto operator"" q_yl(long double l) { return volume<yoctolitre, long double>(l); }
+constexpr auto operator"" _q_yl(unsigned long long l) { return volume<yoctolitre, std::int64_t>(l); }
+constexpr auto operator"" _q_yl(long double l) { return volume<yoctolitre, long double>(l); }
 
 // zl
-constexpr auto operator"" q_zl(unsigned long long l) { return volume<zeptolitre, std::int64_t>(l); }
-constexpr auto operator"" q_zl(long double l) { return volume<zeptolitre, long double>(l); }
+constexpr auto operator"" _q_zl(unsigned long long l) { return volume<zeptolitre, std::int64_t>(l); }
+constexpr auto operator"" _q_zl(long double l) { return volume<zeptolitre, long double>(l); }
 
 // al
-constexpr auto operator"" q_al(unsigned long long l) { return volume<attolitre, std::int64_t>(l); }
-constexpr auto operator"" q_al(long double l) { return volume<attolitre, long double>(l); }
+constexpr auto operator"" _q_al(unsigned long long l) { return volume<attolitre, std::int64_t>(l); }
+constexpr auto operator"" _q_al(long double l) { return volume<attolitre, long double>(l); }
 
 // fl
-constexpr auto operator"" q_fl(unsigned long long l) { return volume<femtolitre, std::int64_t>(l); }
-constexpr auto operator"" q_fl(long double l) { return volume<femtolitre, long double>(l); }
+constexpr auto operator"" _q_fl(unsigned long long l) { return volume<femtolitre, std::int64_t>(l); }
+constexpr auto operator"" _q_fl(long double l) { return volume<femtolitre, long double>(l); }
 
 // pl
-constexpr auto operator"" q_pl(unsigned long long l) { return volume<picolitre, std::int64_t>(l); }
-constexpr auto operator"" q_pl(long double l) { return volume<picolitre, long double>(l); }
+constexpr auto operator"" _q_pl(unsigned long long l) { return volume<picolitre, std::int64_t>(l); }
+constexpr auto operator"" _q_pl(long double l) { return volume<picolitre, long double>(l); }
 
 // nl
-constexpr auto operator"" q_nl(unsigned long long l) { return volume<nanolitre, std::int64_t>(l); }
-constexpr auto operator"" q_nl(long double l) { return volume<nanolitre, long double>(l); }
+constexpr auto operator"" _q_nl(unsigned long long l) { return volume<nanolitre, std::int64_t>(l); }
+constexpr auto operator"" _q_nl(long double l) { return volume<nanolitre, long double>(l); }
 
 // ul
-constexpr auto operator"" q_ul(unsigned long long l) { return volume<microlitre, std::int64_t>(l); }
-constexpr auto operator"" q_ul(long double l) { return volume<microlitre, long double>(l); }
+constexpr auto operator"" _q_ul(unsigned long long l) { return volume<microlitre, std::int64_t>(l); }
+constexpr auto operator"" _q_ul(long double l) { return volume<microlitre, long double>(l); }
 
 // ml
-constexpr auto operator"" q_ml(unsigned long long l) { return volume<millilitre, std::int64_t>(l); }
-constexpr auto operator"" q_ml(long double l) { return volume<millilitre, long double>(l); }
+constexpr auto operator"" _q_ml(unsigned long long l) { return volume<millilitre, std::int64_t>(l); }
+constexpr auto operator"" _q_ml(long double l) { return volume<millilitre, long double>(l); }
 
 // cl
-constexpr auto operator"" q_cl(unsigned long long l) { return volume<centilitre, std::int64_t>(l); }
-constexpr auto operator"" q_cl(long double l) { return volume<centilitre, long double>(l); }
+constexpr auto operator"" _q_cl(unsigned long long l) { return volume<centilitre, std::int64_t>(l); }
+constexpr auto operator"" _q_cl(long double l) { return volume<centilitre, long double>(l); }
 
 // dl
-constexpr auto operator"" q_dl(unsigned long long l) { return volume<decilitre, std::int64_t>(l); }
-constexpr auto operator"" q_dl(long double l) { return volume<decilitre, long double>(l); }
+constexpr auto operator"" _q_dl(unsigned long long l) { return volume<decilitre, std::int64_t>(l); }
+constexpr auto operator"" _q_dl(long double l) { return volume<decilitre, long double>(l); }
 
 // dal
-constexpr auto operator"" q_dal(unsigned long long l) { return volume<decalitre, std::int64_t>(l); }
-constexpr auto operator"" q_dal(long double l) { return volume<decalitre, long double>(l); }
+constexpr auto operator"" _q_dal(unsigned long long l) { return volume<decalitre, std::int64_t>(l); }
+constexpr auto operator"" _q_dal(long double l) { return volume<decalitre, long double>(l); }
 
 // hl
-constexpr auto operator"" q_hl(unsigned long long l) { return volume<hectolitre, std::int64_t>(l); }
-constexpr auto operator"" q_hl(long double l) { return volume<hectolitre, long double>(l); }
+constexpr auto operator"" _q_hl(unsigned long long l) { return volume<hectolitre, std::int64_t>(l); }
+constexpr auto operator"" _q_hl(long double l) { return volume<hectolitre, long double>(l); }
 
 // kl
-constexpr auto operator"" q_kl(unsigned long long l) { return volume<kilolitre, std::int64_t>(l); }
-constexpr auto operator"" q_kl(long double l) { return volume<kilolitre, long double>(l); }
+constexpr auto operator"" _q_kl(unsigned long long l) { return volume<kilolitre, std::int64_t>(l); }
+constexpr auto operator"" _q_kl(long double l) { return volume<kilolitre, long double>(l); }
 
 // Ml
-constexpr auto operator"" q_Ml(unsigned long long l) { return volume<megalitre, std::int64_t>(l); }
-constexpr auto operator"" q_Ml(long double l) { return volume<megalitre, long double>(l); }
+constexpr auto operator"" _q_Ml(unsigned long long l) { return volume<megalitre, std::int64_t>(l); }
+constexpr auto operator"" _q_Ml(long double l) { return volume<megalitre, long double>(l); }
 
 // Gl
-constexpr auto operator"" q_Gl(unsigned long long l) { return volume<gigalitre, std::int64_t>(l); }
-constexpr auto operator"" q_Gl(long double l) { return volume<gigalitre, long double>(l); }
+constexpr auto operator"" _q_Gl(unsigned long long l) { return volume<gigalitre, std::int64_t>(l); }
+constexpr auto operator"" _q_Gl(long double l) { return volume<gigalitre, long double>(l); }
 
 // Tl
-constexpr auto operator"" q_Tl(unsigned long long l) { return volume<teralitre, std::int64_t>(l); }
-constexpr auto operator"" q_Tl(long double l) { return volume<teralitre, long double>(l); }
+constexpr auto operator"" _q_Tl(unsigned long long l) { return volume<teralitre, std::int64_t>(l); }
+constexpr auto operator"" _q_Tl(long double l) { return volume<teralitre, long double>(l); }
 
 // Pl
-constexpr auto operator"" q_Pl(unsigned long long l) { return volume<petalitre, std::int64_t>(l); }
-constexpr auto operator"" q_Pl(long double l) { return volume<petalitre, long double>(l); }
+constexpr auto operator"" _q_Pl(unsigned long long l) { return volume<petalitre, std::int64_t>(l); }
+constexpr auto operator"" _q_Pl(long double l) { return volume<petalitre, long double>(l); }
 
 // El
-constexpr auto operator"" q_El(unsigned long long l) { return volume<exalitre, std::int64_t>(l); }
-constexpr auto operator"" q_El(long double l) { return volume<exalitre, long double>(l); }
+constexpr auto operator"" _q_El(unsigned long long l) { return volume<exalitre, std::int64_t>(l); }
+constexpr auto operator"" _q_El(long double l) { return volume<exalitre, long double>(l); }
 
 // Zl
-constexpr auto operator"" q_Zl(unsigned long long l) { return volume<zettalitre, std::int64_t>(l); }
-constexpr auto operator"" q_Zl(long double l) { return volume<zettalitre, long double>(l); }
+constexpr auto operator"" _q_Zl(unsigned long long l) { return volume<zettalitre, std::int64_t>(l); }
+constexpr auto operator"" _q_Zl(long double l) { return volume<zettalitre, long double>(l); }
 
 // Yl
-constexpr auto operator"" q_Yl(unsigned long long l) { return volume<yottalitre, std::int64_t>(l); }
-constexpr auto operator"" q_Yl(long double l) { return volume<yottalitre, long double>(l); }
+constexpr auto operator"" _q_Yl(unsigned long long l) { return volume<yottalitre, std::int64_t>(l); }
+constexpr auto operator"" _q_Yl(long double l) { return volume<yottalitre, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/typographic/length.h b/src/include/units/physical/typographic/length.h
index 0d4080a8..9bd40b6c 100644
--- a/src/include/units/physical/typographic/length.h
+++ b/src/include/units/physical/typographic/length.h
@@ -36,20 +36,20 @@ struct point_prn : named_scaled_unit<point_prn, "point(prn)", no_prefix, ratio(1
 inline namespace literals {
 
 // pica comp
-constexpr auto operator"" q_pica_comp(unsigned long long l) { return si::length<pica_comp, std::int64_t>(l); }
-constexpr auto operator"" q_pica_comp(long double l) { return si::length<pica_comp, long double>(l); }
+constexpr auto operator"" _q_pica_comp(unsigned long long l) { return si::length<pica_comp, std::int64_t>(l); }
+constexpr auto operator"" _q_pica_comp(long double l) { return si::length<pica_comp, long double>(l); }
 
 // pica prn
-constexpr auto operator"" q_pica_prn(unsigned long long l) { return si::length<pica_prn, std::int64_t>(l); }
-constexpr auto operator"" q_pica_prn(long double l) { return si::length<pica_prn, long double>(l); }
+constexpr auto operator"" _q_pica_prn(unsigned long long l) { return si::length<pica_prn, std::int64_t>(l); }
+constexpr auto operator"" _q_pica_prn(long double l) { return si::length<pica_prn, long double>(l); }
 
 // point comp
-constexpr auto operator"" q_point_comp(unsigned long long l) { return si::length<point_comp, std::int64_t>(l); }
-constexpr auto operator"" q_point_comp(long double l) { return si::length<point_comp, long double>(l); }
+constexpr auto operator"" _q_point_comp(unsigned long long l) { return si::length<point_comp, std::int64_t>(l); }
+constexpr auto operator"" _q_point_comp(long double l) { return si::length<point_comp, long double>(l); }
 
 // point prn
-constexpr auto operator"" q_point_prn(unsigned long long l) { return si::length<point_prn, std::int64_t>(l); }
-constexpr auto operator"" q_point_prn(long double l) { return si::length<point_prn, long double>(l); }
+constexpr auto operator"" _q_point_prn(unsigned long long l) { return si::length<point_prn, std::int64_t>(l); }
+constexpr auto operator"" _q_point_prn(long double l) { return si::length<point_prn, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/physical/us/length.h b/src/include/units/physical/us/length.h
index 860e3cbf..54f97ef9 100644
--- a/src/include/units/physical/us/length.h
+++ b/src/include/units/physical/us/length.h
@@ -40,16 +40,16 @@ struct mile : named_scaled_unit<mile, "mi(us)", no_prefix, ratio(5280), us::foot
 inline namespace literals {
 
 // ft
-constexpr auto operator"" q_ft_us(unsigned long long l) { return si::length<units::physical::us::foot, std::int64_t>(l); }
-constexpr auto operator"" q_ft_us(long double l) { return si::length<units::physical::us::foot, long double>(l); }
+constexpr auto operator"" _q_ft_us(unsigned long long l) { return si::length<units::physical::us::foot, std::int64_t>(l); }
+constexpr auto operator"" _q_ft_us(long double l) { return si::length<units::physical::us::foot, long double>(l); }
 
 // fathom
-constexpr auto operator"" q_fathom_us(unsigned long long l) { return si::length<units::physical::us::fathom, std::int64_t>(l); }
-constexpr auto operator"" q_fathom_us(long double l) { return si::length<units::physical::us::fathom, long double>(l); }
+constexpr auto operator"" _q_fathom_us(unsigned long long l) { return si::length<units::physical::us::fathom, std::int64_t>(l); }
+constexpr auto operator"" _q_fathom_us(long double l) { return si::length<units::physical::us::fathom, long double>(l); }
 
 // ft
-constexpr auto operator"" q_mi_us(unsigned long long l) { return si::length<units::physical::us::mile, std::int64_t>(l); }
-constexpr auto operator"" q_mi_us(long double l) { return si::length<units::physical::us::mile, long double>(l); }
+constexpr auto operator"" _q_mi_us(unsigned long long l) { return si::length<units::physical::us::mile, std::int64_t>(l); }
+constexpr auto operator"" _q_mi_us(long double l) { return si::length<units::physical::us::mile, long double>(l); }
 
 }  // namespace literals
 
diff --git a/src/include/units/quantity_cast.h b/src/include/units/quantity_cast.h
index 7700f05b..3f66b91c 100644
--- a/src/include/units/quantity_cast.h
+++ b/src/include/units/quantity_cast.h
@@ -308,7 +308,7 @@ constexpr ratio cast_ratio(const Q1& from, const Q2& to)
  *
  * This cast gets the target quantity type to cast to. For example:
  *
- * auto q1 = units::quantity_cast<units::physical::si::time<units::physical::si::second>>(1q_ms);
+ * auto q1 = units::quantity_cast<units::physical::si::time<units::physical::si::second>>(1_q_ms);
  *
  * @tparam To a target quantity type to cast to
  */
@@ -332,7 +332,7 @@ template<Quantity To, typename D, typename U, typename Rep>
  *
  * This cast gets only the target dimension to cast to. For example:
  *
- * auto q1 = units::quantity_cast<units::physical::si::acceleration>(200q_Gal);
+ * auto q1 = units::quantity_cast<units::physical::si::acceleration>(200_q_Gal);
  *
  * @tparam ToD a dimension type to use for a target quantity
  */
@@ -351,7 +351,7 @@ template<Dimension ToD, typename D, typename U, typename Rep>
  *
  * This cast gets only the target unit to cast to. For example:
  *
- * auto q1 = units::quantity_cast<units::physical::si::second>(1q_ms);
+ * auto q1 = units::quantity_cast<units::physical::si::second>(1_q_ms);
  *
  * @tparam ToU a unit type to use for a target quantity
  */
@@ -370,7 +370,7 @@ template<Unit ToU, typename D, typename U, typename Rep>
  *
  * This cast gets only representation to cast to. For example:
  *
- * auto q1 = units::quantity_cast<int>(1q_ms);
+ * auto q1 = units::quantity_cast<int>(1_q_ms);
  *
  * @tparam ToRep a representation type to use for a target quantity
  */
@@ -388,11 +388,11 @@ template<ScalableNumber ToRep, typename D, typename U, typename Rep>
  *
  * This cast gets the target quantity point type to cast to or anything that works for quantity_cast. For example:
  *
- * auto q1 = units::quantity_point_cast<decltype(quantity_point{0q_s})>(quantity_point{1q_ms});
- * auto q1 = units::quantity_point_cast<units::physical::si::time<units::physical::si::second>>(quantity_point{1q_ms});
- * auto q1 = units::quantity_point_cast<units::physical::si::acceleration>(quantity_point{200q_Gal});
- * auto q1 = units::quantity_point_cast<units::physical::si::second>(quantity_point{1q_ms});
- * auto q1 = units::quantity_point_cast<int>(quantity_point{1q_ms});
+ * auto q1 = units::quantity_point_cast<decltype(quantity_point{0_q_s})>(quantity_point{1_q_ms});
+ * auto q1 = units::quantity_point_cast<units::physical::si::time<units::physical::si::second>>(quantity_point{1_q_ms});
+ * auto q1 = units::quantity_point_cast<units::physical::si::acceleration>(quantity_point{200_q_Gal});
+ * auto q1 = units::quantity_point_cast<units::physical::si::second>(quantity_point{1_q_ms});
+ * auto q1 = units::quantity_point_cast<int>(quantity_point{1_q_ms});
  *
  * @tparam CastSpec a target quantity point type to cast to or anything that works for quantity_cast
  */
diff --git a/test/unit_test/runtime/digital_info_test.cpp b/test/unit_test/runtime/digital_info_test.cpp
index 09526c1e..f043e1b6 100644
--- a/test/unit_test/runtime/digital_info_test.cpp
+++ b/test/unit_test/runtime/digital_info_test.cpp
@@ -34,25 +34,25 @@ TEST_CASE("operator<< on a data quantity", "[text][ostream]")
   {
     SECTION("named unit")
     {
-      stream << 64q_B;
+      stream << 64_q_B;
       REQUIRE(stream.str() == "64 B");
     }
 
     SECTION("prefixed coherent unit")
     {
-      stream << 256q_Kib;
+      stream << 256_q_Kib;
       REQUIRE(stream.str() == "256 Kib");
     }
 
     SECTION("prefixed non-coherent unit")
     {
-      stream << 1024q_KiB;
+      stream << 1024_q_KiB;
       REQUIRE(stream.str() == "1024 KiB");
     }
 
     SECTION("other unit matching prefix")
     {
-      stream << 8q_Kib * 8q_Kib / 2q_b;
+      stream << 8_q_Kib * 8_q_Kib / 2_q_b;
       REQUIRE(stream.str() == "32 Mib");
     }
   }
diff --git a/test/unit_test/runtime/distribution_test.cpp b/test/unit_test/runtime/distribution_test.cpp
index 101d569c..c391f76c 100644
--- a/test/unit_test/runtime/distribution_test.cpp
+++ b/test/unit_test/runtime/distribution_test.cpp
@@ -498,7 +498,7 @@ TEST_CASE("piecewise_constant_distribution")
   using q = length<metre, rep>;
 
   std::vector<rep> intervals_rep_vec = {1.0, 2.0, 3.0};
-  std::vector<q> intervals_qty_vec = {1.0q_m, 2.0q_m, 3.0q_m};
+  std::vector<q> intervals_qty_vec = {1.0_q_m, 2.0_q_m, 3.0_q_m};
 
   SECTION("default")
   {
@@ -515,7 +515,7 @@ TEST_CASE("piecewise_constant_distribution")
   
   SECTION ("parametrized_input_it") {
     constexpr std::array<rep, 3> intervals_rep = {1.0, 2.0, 3.0};
-    constexpr std::array<q, 3> intervals_qty = {1.0q_m, 2.0q_m, 3.0q_m};
+    constexpr std::array<q, 3> intervals_qty = {1.0_q_m, 2.0_q_m, 3.0_q_m};
     constexpr std::array<rep, 3> weights = {1.0, 2.0, 3.0};
     
     auto stl_dist = std::piecewise_constant_distribution<rep>(intervals_rep.cbegin(), intervals_rep.cend(), weights.cbegin());
@@ -528,7 +528,7 @@ TEST_CASE("piecewise_constant_distribution")
 
   SECTION ("parametrized_initializer_list") {
     std::initializer_list<rep> intervals_rep = {1.0, 2.0, 3.0};
-    std::initializer_list<q> intervals_qty = {1.0q_m, 2.0q_m, 3.0q_m};
+    std::initializer_list<q> intervals_qty = {1.0_q_m, 2.0_q_m, 3.0_q_m};
     
     auto stl_dist = std::piecewise_constant_distribution<rep>(intervals_rep, [](rep val) { return val; });
     auto units_dist = units::piecewise_constant_distribution<q>(intervals_qty, [](q qty) { return qty.count(); });
@@ -540,7 +540,7 @@ TEST_CASE("piecewise_constant_distribution")
   SECTION ("parametrized_range") {
     constexpr std::size_t nw = 2;
     constexpr rep xmin_rep = 1.0, xmax_rep = 3.0;
-    constexpr q xmin_qty = 1.0q_m, xmax_qty = 3.0q_m;
+    constexpr q xmin_qty = 1.0_q_m, xmax_qty = 3.0_q_m;
     
     auto stl_dist = std::piecewise_constant_distribution<rep>(nw, xmin_rep, xmax_rep, [](rep val) { return val; });
     auto units_dist = units::piecewise_constant_distribution<q>(nw, xmin_qty, xmax_qty, [](q qty) { return qty.count(); });
@@ -556,7 +556,7 @@ TEST_CASE("piecewise_linear_distribution")
   using q = length<metre, rep>;
 
   std::vector<rep> intervals_rep_vec = {1.0, 2.0, 3.0};
-  std::vector<q> intervals_qty_vec = {1.0q_m, 2.0q_m, 3.0q_m};
+  std::vector<q> intervals_qty_vec = {1.0_q_m, 2.0_q_m, 3.0_q_m};
 
   SECTION("default")
   {
@@ -573,7 +573,7 @@ TEST_CASE("piecewise_linear_distribution")
   
   SECTION ("parametrized_input_it") {
     constexpr std::array<rep, 3> intervals_rep = {1.0, 2.0, 3.0};
-    constexpr std::array<q, 3> intervals_qty = {1.0q_m, 2.0q_m, 3.0q_m};
+    constexpr std::array<q, 3> intervals_qty = {1.0_q_m, 2.0_q_m, 3.0_q_m};
     constexpr std::array<rep, 3> weights = {1.0, 2.0, 3.0};
     
     auto stl_dist = std::piecewise_linear_distribution<rep>(intervals_rep.cbegin(), intervals_rep.cend(), weights.cbegin());
@@ -586,7 +586,7 @@ TEST_CASE("piecewise_linear_distribution")
 
   SECTION ("parametrized_initializer_list") {
     std::initializer_list<rep> intervals_rep = {1.0, 2.0, 3.0};
-    std::initializer_list<q> intervals_qty = {1.0q_m, 2.0q_m, 3.0q_m};
+    std::initializer_list<q> intervals_qty = {1.0_q_m, 2.0_q_m, 3.0_q_m};
     
     auto stl_dist = std::piecewise_linear_distribution<rep>(intervals_rep, [](rep val) { return val; });
     auto units_dist = units::piecewise_linear_distribution<q>(intervals_qty, [](q qty) { return qty.count(); });
@@ -598,7 +598,7 @@ TEST_CASE("piecewise_linear_distribution")
   SECTION ("parametrized_range") {
     constexpr std::size_t nw = 2;
     constexpr rep xmin_rep = 1.0, xmax_rep = 3.0;
-    constexpr q xmin_qty = 1.0q_m, xmax_qty = 3.0q_m;
+    constexpr q xmin_qty = 1.0_q_m, xmax_qty = 3.0_q_m;
     
     auto stl_dist = std::piecewise_linear_distribution<rep>(nw, xmin_rep, xmax_rep, [](rep val) { return val; });
     auto units_dist = units::piecewise_linear_distribution<q>(nw, xmin_qty, xmax_qty, [](q qty) { return qty.count(); });
diff --git a/test/unit_test/runtime/fmt_test.cpp b/test/unit_test/runtime/fmt_test.cpp
index 01502f6a..16f6a01f 100644
--- a/test/unit_test/runtime/fmt_test.cpp
+++ b/test/unit_test/runtime/fmt_test.cpp
@@ -49,7 +49,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
   {
     SECTION("integral representation")
     {
-      const auto q = 60q_W;
+      const auto q = 60_q_W;
       os << q;
 
       SECTION("iostream")
@@ -70,7 +70,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("floating-point representation")
     {
-      const auto q = 1023.5q_Pa;
+      const auto q = 1023.5_q_Pa;
       os << q;
 
       SECTION("iostream")
@@ -92,7 +92,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
   SECTION("quantity with a predefined prefixed unit")
   {
-    const auto q = 125q_us;
+    const auto q = 125_q_us;
     os << q;
 
     SECTION("iostream")
@@ -158,7 +158,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
   SECTION("quantity with an alias unit")
   {
-    const auto q = 2q_l;
+    const auto q = 2_q_l;
     os << q;
 
     SECTION("iostream")
@@ -179,7 +179,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
   SECTION("quantity with a prefixed alias unit")
   {
-    const auto q = 2q_ml;
+    const auto q = 2_q_ml;
     os << q;
 
     SECTION("iostream")
@@ -204,7 +204,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
     {
       SECTION("acceleration")
       {
-        const auto q = 20q_m / 2q_s / 1q_s;
+        const auto q = 20_q_m / 2_q_s / 1_q_s;
         os << q;
 
         SECTION("iostream")
@@ -225,7 +225,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
       SECTION("volume")
       {
-        const auto q = 2q_m * 1q_m * 1q_m;
+        const auto q = 2_q_m * 1_q_m * 1_q_m;
         os << q;
 
         SECTION("iostream")
@@ -246,7 +246,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
       SECTION("surface tension")
       {
-        const auto q = 20q_N / 2q_m;
+        const auto q = 20_q_N / 2_q_m;
         os << q;
 
         SECTION("iostream")
@@ -270,7 +270,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
     {
       SECTION("speed")
       {
-        const auto q = 20q_km / 2q_h;
+        const auto q = 20_q_km / 2_q_h;
         os << q;
 
         SECTION("iostream")
@@ -317,7 +317,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
   {
     SECTION("unit::ratio as an SI prefix for a dimension with a special symbol")
     {
-      const auto q = 4q_N * 2q_cm;
+      const auto q = 4_q_N * 2_q_cm;
       os << q;
 
       SECTION("iostream")
@@ -338,7 +338,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("unit::ratio for a dimension without a special symbol")
     {
-      const auto q = 2q_um * 2q_cm * 2q_cm;
+      const auto q = 2_q_um * 2_q_cm * 2_q_cm;
       os << q;
 
       SECTION("iostream")
@@ -359,7 +359,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("unit::ratio::num != 1 && unit::ratio::den == 1")
     {
-      const auto q = 4 * 2q_min / (2q_s * 2q_s);
+      const auto q = 4 * 2_q_min / (2_q_s * 2_q_s);
       os << q;
 
       SECTION("iostream")
@@ -380,7 +380,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("unit::ratio::num == 1 && unit::ratio::den != 1")
     {
-      const auto q = 20q_J / 2q_min;
+      const auto q = 20_q_J / 2_q_min;
       os << q;
 
       SECTION("iostream")
@@ -401,7 +401,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("unit::ratio::num != 1 && unit::ratio::den != 1")
     {
-      const auto q = 60q_kJ / 2q_min;
+      const auto q = 60_q_kJ / 2_q_min;
       os << q;
 
       SECTION("iostream")
@@ -425,7 +425,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
   {
     SECTION("one with ratio == 1")
     {
-      const auto q = 4q_m / 2q_m;
+      const auto q = 4_q_m / 2_q_m;
       os << q;
 
       SECTION("iostream")
@@ -446,7 +446,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("one with ratio.exp != 0")
     {
-      const auto q = 4q_km / 2q_m;
+      const auto q = 4_q_km / 2_q_m;
       os << q;
 
       SECTION("iostream")
@@ -467,7 +467,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("percents")
     {
-      const auto q = quantity_cast<percent>(15.q_m / 100.q_m);
+      const auto q = quantity_cast<percent>(15._q_m / 100._q_m);
       os << q;
 
       SECTION("iostream")
@@ -493,7 +493,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
     {
       SECTION("SI base units")
       {
-        const auto q = 2q_s * 2q_m * 2q_kg;
+        const auto q = 2_q_s * 2_q_m * 2_q_kg;
         os << q;
 
         SECTION("iostream")
@@ -514,7 +514,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
       SECTION("CGS base units")
       {
-        const auto q = 2.q_s * cgs::length<cgs::centimetre>(2) * cgs::mass<cgs::gram>(2);
+        const auto q = 2._q_s * cgs::length<cgs::centimetre>(2) * cgs::mass<cgs::gram>(2);
         os << q;
 
         SECTION("iostream")
@@ -536,7 +536,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("unit::ratio as an SI prefix")
     {
-      const auto q = 4q_km * 2q_s;
+      const auto q = 4_q_km * 2_q_s;
       os << q;
 
       SECTION("iostream")
@@ -557,7 +557,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("unit::ratio::num != 1 && unit::ratio::den == 1")
     {
-      const auto q = 4q_kg * 2q_min / (2q_s * 2q_s);
+      const auto q = 4_q_kg * 2_q_min / (2_q_s * 2_q_s);
       os << q;
 
       SECTION("iostream")
@@ -578,7 +578,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("unit::ratio::num == 1 && unit::ratio::den != 1")
     {
-      const auto q = 20q_kg / 2q_min;
+      const auto q = 20_q_kg / 2_q_min;
       os << q;
 
       SECTION("iostream")
@@ -599,7 +599,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("CGS base units")
     {
-      const auto q = 2.q_s * cgs::length<si::metre>(2) * cgs::mass<si::kilogram>(2);
+      const auto q = 2._q_s * cgs::length<si::metre>(2) * cgs::mass<si::kilogram>(2);
       os << q;
 
       SECTION("iostream")
@@ -620,7 +620,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("unit::ratio::num != 1 && unit::ratio::den != 1")
     {
-      const auto q = 60q_min / 2q_km;
+      const auto q = 60_q_min / 2_q_km;
       os << q;
 
       SECTION("iostream")
@@ -641,7 +641,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("exponent::num == 1 && exponent::den == 1")
     {
-      const auto q = 4q_m * 2q_s;
+      const auto q = 4_q_m * 2_q_s;
       os << q;
 
       SECTION("iostream")
@@ -662,7 +662,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("exponent::num == 2 && exponent::den == 1 for positive exponent")
     {
-      const auto q = 4q_m * 2q_s * 2q_s;
+      const auto q = 4_q_m * 2_q_s * 2_q_s;
       os << q;
 
       SECTION("iostream")
@@ -683,7 +683,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("exponent::num == 2 && exponent::den == 1 for negative exponent (first dimension)")
     {
-      const auto q = 8q_s / 2q_m / 2q_m;
+      const auto q = 8_q_s / 2_q_m / 2_q_m;
       os << q;
 
       SECTION("iostream")
@@ -704,7 +704,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("exponent::num == 2 && exponent::den == 1 for negative exponent (not first dimension)")
     {
-      const auto q = 8q_m / 2q_kg / 2q_kg;
+      const auto q = 8_q_m / 2_q_kg / 2_q_kg;
       os << q;
 
       SECTION("iostream")
@@ -725,7 +725,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("fractional positive exponent")
     {
-      const auto q = sqrt(9q_m);
+      const auto q = sqrt(9_q_m);
       os << q;
 
       SECTION("iostream")
@@ -746,7 +746,7 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
     SECTION("fractional negative exponent")
     {
-      const auto q = sqrt(9 / 1q_m);
+      const auto q = sqrt(9 / 1_q_m);
       os << q;
 
       SECTION("iostream")
@@ -773,12 +773,12 @@ TEST_CASE("format string with only %Q should print quantity value only", "[text]
   {
     SECTION("positive value")
     {
-      CHECK(fmt::format("{:%Q}", 123q_km_per_h) == "123");
+      CHECK(fmt::format("{:%Q}", 123_q_km_per_h) == "123");
     }
 
     SECTION("negative value")
     {
-      CHECK(fmt::format("{:%Q}", 5q_m - 10q_m) == "-5");
+      CHECK(fmt::format("{:%Q}", 5_q_m - 10_q_m) == "-5");
     }
   }
 
@@ -786,12 +786,12 @@ TEST_CASE("format string with only %Q should print quantity value only", "[text]
   {
     SECTION("positive value")
     {
-      CHECK(fmt::format("{:%Q}", 221.q_km / 2q_h) == "110.5");
+      CHECK(fmt::format("{:%Q}", 221._q_km / 2_q_h) == "110.5");
     }
 
     SECTION("negative value")
     {
-      CHECK(fmt::format("{:%Q}", 3.14q_m - 10q_m) == "-6.86");
+      CHECK(fmt::format("{:%Q}", 3.14_q_m - 10_q_m) == "-6.86");
     }
 
     SECTION("nan")
@@ -815,24 +815,24 @@ TEST_CASE("format string with only %q should print quantity unit symbol only", "
 {
   SECTION("standard format for a unit without Unicode symbols")
   {
-    CHECK(fmt::format("{:%q}", 123q_km_per_h) == "km/h");
+    CHECK(fmt::format("{:%q}", 123_q_km_per_h) == "km/h");
   }
 
   SECTION("ASCII format for a unit without Unicode symbols")
   {
-    CHECK(fmt::format("{:%Aq}", 123q_km_per_h) == "km/h");
+    CHECK(fmt::format("{:%Aq}", 123_q_km_per_h) == "km/h");
   }
 
   SECTION("standard format for a unit with Unicode symbols")
   {
     SECTION("Unicode signs in a unit symbol")
     {
-      CHECK(fmt::format("{:%q}", 123q_kR) == "kΩ");
+      CHECK(fmt::format("{:%q}", 123_q_kR) == "kΩ");
     }
 
     SECTION("Unicode signs in a unit symbol prefix")
     {
-      CHECK(fmt::format("{:%q}", 123q_uV) == "µV");
+      CHECK(fmt::format("{:%q}", 123_q_uV) == "µV");
     }
   }
 
@@ -840,12 +840,12 @@ TEST_CASE("format string with only %q should print quantity unit symbol only", "
   {
     SECTION("Unicode signs in a unit symbol")
     {
-      CHECK(fmt::format("{:%Aq}", 123q_kR) == "kohm");
+      CHECK(fmt::format("{:%Aq}", 123_q_kR) == "kohm");
     }
 
     SECTION("Unicode signs in a unit symbol prefix")
     {
-      CHECK(fmt::format("{:%Aq}", 123q_uV) == "uV");
+      CHECK(fmt::format("{:%Aq}", 123_q_uV) == "uV");
     }
   }
 }
@@ -854,32 +854,32 @@ TEST_CASE("%q and %Q can be put anywhere in a format string", "[text][fmt]")
 {
   SECTION("no space")
   {
-    CHECK(fmt::format("{:%Q%q}", 123q_km_per_h) == "123km/h");
+    CHECK(fmt::format("{:%Q%q}", 123_q_km_per_h) == "123km/h");
   }
 
   SECTION("separator")
   {
-    CHECK(fmt::format("{:%Q###%q}", 123q_km_per_h) == "123###km/h");
+    CHECK(fmt::format("{:%Q###%q}", 123_q_km_per_h) == "123###km/h");
   }
 
   SECTION("opposite order")
   {
-    CHECK(fmt::format("{:%q %Q}", 123q_km_per_h) == "km/h 123");
+    CHECK(fmt::format("{:%q %Q}", 123_q_km_per_h) == "km/h 123");
   }
 
   SECTION("tabulator")
   {
-    CHECK(fmt::format("{:%Q%t%q}", 123q_km_per_h) == "123\tkm/h");
+    CHECK(fmt::format("{:%Q%t%q}", 123_q_km_per_h) == "123\tkm/h");
   }
 
   SECTION("new line")
   {
-    CHECK(fmt::format("{:%Q%n%q}", 123q_km_per_h) == "123\nkm/h");
+    CHECK(fmt::format("{:%Q%n%q}", 123_q_km_per_h) == "123\nkm/h");
   }
 
   SECTION("% sign")
   {
-    CHECK(fmt::format("{:%Q%% %q}", 123q_km_per_h) == "123% km/h");
+    CHECK(fmt::format("{:%Q%% %q}", 123_q_km_per_h) == "123% km/h");
   }
 }
 
@@ -891,87 +891,87 @@ TEST_CASE("fill and align specification", "[text][fmt][ostream]")
 
     SECTION("width = 10")
     {
-      os << "|" << std::setw(10) << 123q_m << "|";
+      os << "|" << std::setw(10) << 123_q_m << "|";
       CHECK(os.str() == "|     123 m|");
     }
 
     SECTION("width = 10, align = right")
     {
-      os << "|" << std::setw(10) << std::right << 123q_m << "|";
+      os << "|" << std::setw(10) << std::right << 123_q_m << "|";
       CHECK(os.str() == "|     123 m|");
     }
 
     SECTION("width = 10, align = left")
     {
-      os << "|" << std::setw(10) << std::left << 123q_m << "|";
+      os << "|" << std::setw(10) << std::left << 123_q_m << "|";
       CHECK(os.str() == "|123 m     |");
     }
 
     SECTION("width = 10, fill = *")
     {
-      os << "|" << std::setw(10) << std::setfill('*') << 123q_m << "|";
+      os << "|" << std::setw(10) << std::setfill('*') << 123_q_m << "|";
       CHECK(os.str() == "|*****123 m|");
     }
 
     SECTION("width = 10, fill = *, align = right")
     {
-      os << "|" << std::setw(10) << std::setfill('*') << std::right << 123q_m << "|";
+      os << "|" << std::setw(10) << std::setfill('*') << std::right << 123_q_m << "|";
       CHECK(os.str() == "|*****123 m|");
     }
 
     SECTION("width = 10, fill = *, align = left")
     {
-      os << "|" << std::setw(10) << std::setfill('*') << std::left << 123q_m << "|";
+      os << "|" << std::setw(10) << std::setfill('*') << std::left << 123_q_m << "|";
       CHECK(os.str() == "|123 m*****|");
     }
   }
 
   SECTION("default format {} on a quantity")
   {
-    CHECK(fmt::format("|{:0}|", 123q_m) == "|123 m|");
-    CHECK(fmt::format("|{:10}|", 123q_m) == "|     123 m|");
-    CHECK(fmt::format("|{:<10}|", 123q_m) == "|123 m     |");
-    CHECK(fmt::format("|{:>10}|", 123q_m) == "|     123 m|");
-    CHECK(fmt::format("|{:^10}|", 123q_m) == "|  123 m   |");
-    CHECK(fmt::format("|{:*<10}|", 123q_m) == "|123 m*****|");
-    CHECK(fmt::format("|{:*>10}|", 123q_m) == "|*****123 m|");
-    CHECK(fmt::format("|{:*^10}|", 123q_m) == "|**123 m***|");
+    CHECK(fmt::format("|{:0}|", 123_q_m) == "|123 m|");
+    CHECK(fmt::format("|{:10}|", 123_q_m) == "|     123 m|");
+    CHECK(fmt::format("|{:<10}|", 123_q_m) == "|123 m     |");
+    CHECK(fmt::format("|{:>10}|", 123_q_m) == "|     123 m|");
+    CHECK(fmt::format("|{:^10}|", 123_q_m) == "|  123 m   |");
+    CHECK(fmt::format("|{:*<10}|", 123_q_m) == "|123 m*****|");
+    CHECK(fmt::format("|{:*>10}|", 123_q_m) == "|*****123 m|");
+    CHECK(fmt::format("|{:*^10}|", 123_q_m) == "|**123 m***|");
   }
 
   SECTION("full format {:%Q %q} on a quantity")
   {
-    CHECK(fmt::format("|{:0%Q%q}|", 123q_m) == "|123m|");
-    CHECK(fmt::format("|{:10%Q%q}|", 123q_m) == "|      123m|");
-    CHECK(fmt::format("|{:<10%Q%q}|", 123q_m) == "|123m      |");
-    CHECK(fmt::format("|{:>10%Q%q}|", 123q_m) == "|      123m|");
-    CHECK(fmt::format("|{:^10%Q%q}|", 123q_m) == "|   123m   |");
-    CHECK(fmt::format("|{:*<10%Q%q}|", 123q_m) == "|123m******|");
-    CHECK(fmt::format("|{:*>10%Q%q}|", 123q_m) == "|******123m|");
-    CHECK(fmt::format("|{:*^10%Q%q}|", 123q_m) == "|***123m***|");
+    CHECK(fmt::format("|{:0%Q%q}|", 123_q_m) == "|123m|");
+    CHECK(fmt::format("|{:10%Q%q}|", 123_q_m) == "|      123m|");
+    CHECK(fmt::format("|{:<10%Q%q}|", 123_q_m) == "|123m      |");
+    CHECK(fmt::format("|{:>10%Q%q}|", 123_q_m) == "|      123m|");
+    CHECK(fmt::format("|{:^10%Q%q}|", 123_q_m) == "|   123m   |");
+    CHECK(fmt::format("|{:*<10%Q%q}|", 123_q_m) == "|123m******|");
+    CHECK(fmt::format("|{:*>10%Q%q}|", 123_q_m) == "|******123m|");
+    CHECK(fmt::format("|{:*^10%Q%q}|", 123_q_m) == "|***123m***|");
   }
 
   SECTION("value only format {:%Q} on a quantity")
   {
-    CHECK(fmt::format("|{:0%Q}|", 123q_m) == "|123|");
-    CHECK(fmt::format("|{:10%Q}|", 123q_m) == "|       123|");
-    CHECK(fmt::format("|{:<10%Q}|", 123q_m) == "|123       |");
-    CHECK(fmt::format("|{:>10%Q}|", 123q_m) == "|       123|");
-    CHECK(fmt::format("|{:^10%Q}|", 123q_m) == "|   123    |");
-    CHECK(fmt::format("|{:*<10%Q}|", 123q_m) == "|123*******|");
-    CHECK(fmt::format("|{:*>10%Q}|", 123q_m) == "|*******123|");
-    CHECK(fmt::format("|{:*^10%Q}|", 123q_m) == "|***123****|");
+    CHECK(fmt::format("|{:0%Q}|", 123_q_m) == "|123|");
+    CHECK(fmt::format("|{:10%Q}|", 123_q_m) == "|       123|");
+    CHECK(fmt::format("|{:<10%Q}|", 123_q_m) == "|123       |");
+    CHECK(fmt::format("|{:>10%Q}|", 123_q_m) == "|       123|");
+    CHECK(fmt::format("|{:^10%Q}|", 123_q_m) == "|   123    |");
+    CHECK(fmt::format("|{:*<10%Q}|", 123_q_m) == "|123*******|");
+    CHECK(fmt::format("|{:*>10%Q}|", 123_q_m) == "|*******123|");
+    CHECK(fmt::format("|{:*^10%Q}|", 123_q_m) == "|***123****|");
   }
 
   SECTION("symbol only format {:%q} on a quantity")
   {
-    CHECK(fmt::format("|{:0%q}|", 123q_m) == "|m|");
-    CHECK(fmt::format("|{:10%q}|", 123q_m) == "|m         |");
-    CHECK(fmt::format("|{:<10%q}|", 123q_m) == "|m         |");
-    CHECK(fmt::format("|{:>10%q}|", 123q_m) == "|         m|");
-    CHECK(fmt::format("|{:^10%q}|", 123q_m) == "|    m     |");
-    CHECK(fmt::format("|{:*<10%q}|", 123q_m) == "|m*********|");
-    CHECK(fmt::format("|{:*>10%q}|", 123q_m) == "|*********m|");
-    CHECK(fmt::format("|{:*^10%q}|", 123q_m) == "|****m*****|");
+    CHECK(fmt::format("|{:0%q}|", 123_q_m) == "|m|");
+    CHECK(fmt::format("|{:10%q}|", 123_q_m) == "|m         |");
+    CHECK(fmt::format("|{:<10%q}|", 123_q_m) == "|m         |");
+    CHECK(fmt::format("|{:>10%q}|", 123_q_m) == "|         m|");
+    CHECK(fmt::format("|{:^10%q}|", 123_q_m) == "|    m     |");
+    CHECK(fmt::format("|{:*<10%q}|", 123_q_m) == "|m*********|");
+    CHECK(fmt::format("|{:*>10%q}|", 123_q_m) == "|*********m|");
+    CHECK(fmt::format("|{:*^10%q}|", 123_q_m) == "|****m*****|");
   }
 }
 
@@ -982,16 +982,16 @@ TEST_CASE("sign specification", "[text][fmt]")
 
   SECTION("full format {:%Q %q} on a quantity")
   {
-    CHECK(fmt::format("{0:%Q%q},{0:%+Q%q},{0:%-Q%q},{0:% Q%q}", 1q_m) == "1m,+1m,1m, 1m");
-    CHECK(fmt::format("{0:%Q%q},{0:%+Q%q},{0:%-Q%q},{0:% Q%q}", -1q_m) == "-1m,-1m,-1m,-1m");
+    CHECK(fmt::format("{0:%Q%q},{0:%+Q%q},{0:%-Q%q},{0:% Q%q}", 1_q_m) == "1m,+1m,1m, 1m");
+    CHECK(fmt::format("{0:%Q%q},{0:%+Q%q},{0:%-Q%q},{0:% Q%q}", -1_q_m) == "-1m,-1m,-1m,-1m");
     CHECK(fmt::format("{0:%Q%q},{0:%+Q%q},{0:%-Q%q},{0:% Q%q}", inf) == "infm,+infm,infm, infm");
     CHECK(fmt::format("{0:%Q%q},{0:%+Q%q},{0:%-Q%q},{0:% Q%q}", nan) == "nanm,+nanm,nanm, nanm");
   }
 
   SECTION("value only format {:%Q} on a quantity")
   {
-    CHECK(fmt::format("{0:%Q},{0:%+Q},{0:%-Q},{0:% Q}", 1q_m) == "1,+1,1, 1");
-    CHECK(fmt::format("{0:%Q},{0:%+Q},{0:%-Q},{0:% Q}", -1q_m) == "-1,-1,-1,-1");
+    CHECK(fmt::format("{0:%Q},{0:%+Q},{0:%-Q},{0:% Q}", 1_q_m) == "1,+1,1, 1");
+    CHECK(fmt::format("{0:%Q},{0:%+Q},{0:%-Q},{0:% Q}", -1_q_m) == "-1,-1,-1,-1");
     CHECK(fmt::format("{0:%Q},{0:%+Q},{0:%-Q},{0:% Q}", inf) == "inf,+inf,inf, inf");
     CHECK(fmt::format("{0:%Q},{0:%+Q},{0:%-Q},{0:% Q}", nan) == "nan,+nan,nan, nan");
   }
@@ -1001,32 +1001,32 @@ TEST_CASE("precision specification", "[text][fmt]")
 {
   SECTION("full format {:%Q %q} on a quantity")
   {
-    CHECK(fmt::format("{:%.0Q %q}", 1.2345q_m) == "1 m");
-    CHECK(fmt::format("{:%.1Q %q}", 1.2345q_m) == "1.2 m");
-    CHECK(fmt::format("{:%.2Q %q}", 1.2345q_m) == "1.23 m");
+    CHECK(fmt::format("{:%.0Q %q}", 1.2345_q_m) == "1 m");
+    CHECK(fmt::format("{:%.1Q %q}", 1.2345_q_m) == "1.2 m");
+    CHECK(fmt::format("{:%.2Q %q}", 1.2345_q_m) == "1.23 m");
 #ifdef COMP_MSVC
-    CHECK(fmt::format("{:%.3Q %q}", 1.2345q_m) == "1.234 m");
+    CHECK(fmt::format("{:%.3Q %q}", 1.2345_q_m) == "1.234 m");
 #else
-    CHECK(fmt::format("{:%.3Q %q}", 1.2345q_m) == "1.235 m");
+    CHECK(fmt::format("{:%.3Q %q}", 1.2345_q_m) == "1.235 m");
 #endif
-    CHECK(fmt::format("{:%.4Q %q}", 1.2345q_m) == "1.2345 m");
-    CHECK(fmt::format("{:%.5Q %q}", 1.2345q_m) == "1.23450 m");
-    CHECK(fmt::format("{:%.10Q %q}", 1.2345q_m) == "1.2345000000 m");
+    CHECK(fmt::format("{:%.4Q %q}", 1.2345_q_m) == "1.2345 m");
+    CHECK(fmt::format("{:%.5Q %q}", 1.2345_q_m) == "1.23450 m");
+    CHECK(fmt::format("{:%.10Q %q}", 1.2345_q_m) == "1.2345000000 m");
   }
 
   SECTION("value only format {:%Q} on a quantity")
   {
-    CHECK(fmt::format("{:%.0Q}", 1.2345q_m) == "1");
-    CHECK(fmt::format("{:%.1Q}", 1.2345q_m) == "1.2");
-    CHECK(fmt::format("{:%.2Q}", 1.2345q_m) == "1.23");
+    CHECK(fmt::format("{:%.0Q}", 1.2345_q_m) == "1");
+    CHECK(fmt::format("{:%.1Q}", 1.2345_q_m) == "1.2");
+    CHECK(fmt::format("{:%.2Q}", 1.2345_q_m) == "1.23");
 #ifdef COMP_MSVC
-    CHECK(fmt::format("{:%.3Q}", 1.2345q_m) == "1.234");
+    CHECK(fmt::format("{:%.3Q}", 1.2345_q_m) == "1.234");
 #else
-    CHECK(fmt::format("{:%.3Q}", 1.2345q_m) == "1.235");
+    CHECK(fmt::format("{:%.3Q}", 1.2345_q_m) == "1.235");
 #endif
-    CHECK(fmt::format("{:%.4Q}", 1.2345q_m) == "1.2345");
-    CHECK(fmt::format("{:%.5Q}", 1.2345q_m) == "1.23450");
-    CHECK(fmt::format("{:%.10Q}", 1.2345q_m) == "1.2345000000");
+    CHECK(fmt::format("{:%.4Q}", 1.2345_q_m) == "1.2345");
+    CHECK(fmt::format("{:%.5Q}", 1.2345_q_m) == "1.23450");
+    CHECK(fmt::format("{:%.10Q}", 1.2345_q_m) == "1.2345000000");
   }
 }
 
@@ -1034,12 +1034,12 @@ TEST_CASE("precision specification for integral representation should throw", "[
 {
   SECTION("full format {:%Q %q} on a quantity")
   {
-    REQUIRE_THROWS_MATCHES(fmt::format("{:%.1Q %q}", 1q_m), fmt::format_error, Message("precision not allowed for integral quantity representation"));
+    REQUIRE_THROWS_MATCHES(fmt::format("{:%.1Q %q}", 1_q_m), fmt::format_error, Message("precision not allowed for integral quantity representation"));
   }
 
   SECTION("value only format {:%Q} on a quantity")
   {
-    REQUIRE_THROWS_MATCHES(fmt::format("{:%.1Q}", 1q_m), fmt::format_error, Message("precision not allowed for integral quantity representation"));
+    REQUIRE_THROWS_MATCHES(fmt::format("{:%.1Q}", 1_q_m), fmt::format_error, Message("precision not allowed for integral quantity representation"));
   }
 }
 
@@ -1047,70 +1047,70 @@ TEST_CASE("type specification", "[text][fmt]")
 {
   SECTION("full format {:%Q %q} on a quantity")
   {
-    CHECK(fmt::format("{:%bQ %q}", 42q_m) == "101010 m");
-    CHECK(fmt::format("{:%BQ %q}", 42q_m) == "101010 m");
-    CHECK(fmt::format("{:%dQ %q}", 42q_m) == "42 m");
-    CHECK(fmt::format("{:%oQ %q}", 42q_m) == "52 m");
-    CHECK(fmt::format("{:%xQ %q}", 42q_m) == "2a m");
-    CHECK(fmt::format("{:%XQ %q}", 42q_m) == "2A m");
+    CHECK(fmt::format("{:%bQ %q}", 42_q_m) == "101010 m");
+    CHECK(fmt::format("{:%BQ %q}", 42_q_m) == "101010 m");
+    CHECK(fmt::format("{:%dQ %q}", 42_q_m) == "42 m");
+    CHECK(fmt::format("{:%oQ %q}", 42_q_m) == "52 m");
+    CHECK(fmt::format("{:%xQ %q}", 42_q_m) == "2a m");
+    CHECK(fmt::format("{:%XQ %q}", 42_q_m) == "2A m");
 
 #ifdef COMP_MSVC
-    CHECK(fmt::format("{:%aQ %q}",   1.2345678q_m) == "0x1.3c0ca2a5b1d5dp+0 m");
-    CHECK(fmt::format("{:%.3aQ %q}", 1.2345678q_m) == "0x1.3c1p+0 m");
-    CHECK(fmt::format("{:%AQ %q}",   1.2345678q_m) == "0X1.3C0CA2A5B1D5DP+0 m");
-    CHECK(fmt::format("{:%.3AQ %q}", 1.2345678q_m) == "0X1.3C1P+0 m");
+    CHECK(fmt::format("{:%aQ %q}",   1.2345678_q_m) == "0x1.3c0ca2a5b1d5dp+0 m");
+    CHECK(fmt::format("{:%.3aQ %q}", 1.2345678_q_m) == "0x1.3c1p+0 m");
+    CHECK(fmt::format("{:%AQ %q}",   1.2345678_q_m) == "0X1.3C0CA2A5B1D5DP+0 m");
+    CHECK(fmt::format("{:%.3AQ %q}", 1.2345678_q_m) == "0X1.3C1P+0 m");
 #else
-    CHECK(fmt::format("{:%aQ %q}",   1.2345678q_m) == "0x9.e065152d8eae841p-3 m");
-    CHECK(fmt::format("{:%.3aQ %q}", 1.2345678q_m) == "0x9.e06p-3 m");
-    CHECK(fmt::format("{:%AQ %q}",   1.2345678q_m) == "0X9.E065152D8EAE841P-3 m");
-    CHECK(fmt::format("{:%.3AQ %q}", 1.2345678q_m) == "0X9.E06P-3 m");
+    CHECK(fmt::format("{:%aQ %q}",   1.2345678_q_m) == "0x9.e065152d8eae841p-3 m");
+    CHECK(fmt::format("{:%.3aQ %q}", 1.2345678_q_m) == "0x9.e06p-3 m");
+    CHECK(fmt::format("{:%AQ %q}",   1.2345678_q_m) == "0X9.E065152D8EAE841P-3 m");
+    CHECK(fmt::format("{:%.3AQ %q}", 1.2345678_q_m) == "0X9.E06P-3 m");
 #endif
-    CHECK(fmt::format("{:%eQ %q}",   1.2345678q_m) == "1.234568e+00 m");
-    CHECK(fmt::format("{:%.3eQ %q}", 1.2345678q_m) == "1.235e+00 m");
-    CHECK(fmt::format("{:%EQ %q}",   1.2345678q_m) == "1.234568E+00 m");
-    CHECK(fmt::format("{:%.3EQ %q}", 1.2345678q_m) == "1.235E+00 m");
-    CHECK(fmt::format("{:%gQ %q}",   1.2345678q_m) == "1.23457 m");
-    CHECK(fmt::format("{:%gQ %q}",   1.2345678e8q_m) == "1.23457e+08 m");
-    CHECK(fmt::format("{:%.3gQ %q}", 1.2345678q_m) == "1.23 m");
-    CHECK(fmt::format("{:%.3gQ %q}", 1.2345678e8q_m) == "1.23e+08 m");
-    CHECK(fmt::format("{:%GQ %q}",   1.2345678q_m) == "1.23457 m");
-    CHECK(fmt::format("{:%GQ %q}",   1.2345678e8q_m) == "1.23457E+08 m");
-    CHECK(fmt::format("{:%.3GQ %q}", 1.2345678q_m) == "1.23 m");
-    CHECK(fmt::format("{:%.3GQ %q}", 1.2345678e8q_m) == "1.23E+08 m");
+    CHECK(fmt::format("{:%eQ %q}",   1.2345678_q_m) == "1.234568e+00 m");
+    CHECK(fmt::format("{:%.3eQ %q}", 1.2345678_q_m) == "1.235e+00 m");
+    CHECK(fmt::format("{:%EQ %q}",   1.2345678_q_m) == "1.234568E+00 m");
+    CHECK(fmt::format("{:%.3EQ %q}", 1.2345678_q_m) == "1.235E+00 m");
+    CHECK(fmt::format("{:%gQ %q}",   1.2345678_q_m) == "1.23457 m");
+    CHECK(fmt::format("{:%gQ %q}",   1.2345678e8_q_m) == "1.23457e+08 m");
+    CHECK(fmt::format("{:%.3gQ %q}", 1.2345678_q_m) == "1.23 m");
+    CHECK(fmt::format("{:%.3gQ %q}", 1.2345678e8_q_m) == "1.23e+08 m");
+    CHECK(fmt::format("{:%GQ %q}",   1.2345678_q_m) == "1.23457 m");
+    CHECK(fmt::format("{:%GQ %q}",   1.2345678e8_q_m) == "1.23457E+08 m");
+    CHECK(fmt::format("{:%.3GQ %q}", 1.2345678_q_m) == "1.23 m");
+    CHECK(fmt::format("{:%.3GQ %q}", 1.2345678e8_q_m) == "1.23E+08 m");
   }
 
   SECTION("value only format {:%Q} on a quantity")
   {
-    CHECK(fmt::format("{:%bQ}", 42q_m) == "101010");
-    CHECK(fmt::format("{:%BQ}", 42q_m) == "101010");
-    CHECK(fmt::format("{:%dQ}", 42q_m) == "42");
-    CHECK(fmt::format("{:%oQ}", 42q_m) == "52");
-    CHECK(fmt::format("{:%xQ}", 42q_m) == "2a");
-    CHECK(fmt::format("{:%XQ}", 42q_m) == "2A");
+    CHECK(fmt::format("{:%bQ}", 42_q_m) == "101010");
+    CHECK(fmt::format("{:%BQ}", 42_q_m) == "101010");
+    CHECK(fmt::format("{:%dQ}", 42_q_m) == "42");
+    CHECK(fmt::format("{:%oQ}", 42_q_m) == "52");
+    CHECK(fmt::format("{:%xQ}", 42_q_m) == "2a");
+    CHECK(fmt::format("{:%XQ}", 42_q_m) == "2A");
 
 #ifdef COMP_MSVC
-    CHECK(fmt::format("{:%aQ}",   1.2345678q_m) == "0x1.3c0ca2a5b1d5dp+0");
-    CHECK(fmt::format("{:%.3aQ}", 1.2345678q_m) == "0x1.3c1p+0");
-    CHECK(fmt::format("{:%AQ}",   1.2345678q_m) == "0X1.3C0CA2A5B1D5DP+0");
-    CHECK(fmt::format("{:%.3AQ}", 1.2345678q_m) == "0X1.3C1P+0");
+    CHECK(fmt::format("{:%aQ}",   1.2345678_q_m) == "0x1.3c0ca2a5b1d5dp+0");
+    CHECK(fmt::format("{:%.3aQ}", 1.2345678_q_m) == "0x1.3c1p+0");
+    CHECK(fmt::format("{:%AQ}",   1.2345678_q_m) == "0X1.3C0CA2A5B1D5DP+0");
+    CHECK(fmt::format("{:%.3AQ}", 1.2345678_q_m) == "0X1.3C1P+0");
 #else
-    CHECK(fmt::format("{:%aQ}",   1.2345678q_m) == "0x9.e065152d8eae841p-3");
-    CHECK(fmt::format("{:%.3aQ}", 1.2345678q_m) == "0x9.e06p-3");
-    CHECK(fmt::format("{:%AQ}",   1.2345678q_m) == "0X9.E065152D8EAE841P-3");
-    CHECK(fmt::format("{:%.3AQ}", 1.2345678q_m) == "0X9.E06P-3");
+    CHECK(fmt::format("{:%aQ}",   1.2345678_q_m) == "0x9.e065152d8eae841p-3");
+    CHECK(fmt::format("{:%.3aQ}", 1.2345678_q_m) == "0x9.e06p-3");
+    CHECK(fmt::format("{:%AQ}",   1.2345678_q_m) == "0X9.E065152D8EAE841P-3");
+    CHECK(fmt::format("{:%.3AQ}", 1.2345678_q_m) == "0X9.E06P-3");
 #endif
-    CHECK(fmt::format("{:%eQ}",   1.2345678q_m) == "1.234568e+00");
-    CHECK(fmt::format("{:%.3eQ}", 1.2345678q_m) == "1.235e+00");
-    CHECK(fmt::format("{:%EQ}",   1.2345678q_m) == "1.234568E+00");
-    CHECK(fmt::format("{:%.3EQ}", 1.2345678q_m) == "1.235E+00");
-    CHECK(fmt::format("{:%gQ}",   1.2345678q_m) == "1.23457");
-    CHECK(fmt::format("{:%gQ}",   1.2345678e8q_m) == "1.23457e+08");
-    CHECK(fmt::format("{:%.3gQ}", 1.2345678q_m) == "1.23");
-    CHECK(fmt::format("{:%.3gQ}", 1.2345678e8q_m) == "1.23e+08");
-    CHECK(fmt::format("{:%GQ}",   1.2345678q_m) == "1.23457");
-    CHECK(fmt::format("{:%GQ}",   1.2345678e8q_m) == "1.23457E+08");
-    CHECK(fmt::format("{:%.3GQ}", 1.2345678q_m) == "1.23");
-    CHECK(fmt::format("{:%.3GQ}", 1.2345678e8q_m) == "1.23E+08");
+    CHECK(fmt::format("{:%eQ}",   1.2345678_q_m) == "1.234568e+00");
+    CHECK(fmt::format("{:%.3eQ}", 1.2345678_q_m) == "1.235e+00");
+    CHECK(fmt::format("{:%EQ}",   1.2345678_q_m) == "1.234568E+00");
+    CHECK(fmt::format("{:%.3EQ}", 1.2345678_q_m) == "1.235E+00");
+    CHECK(fmt::format("{:%gQ}",   1.2345678_q_m) == "1.23457");
+    CHECK(fmt::format("{:%gQ}",   1.2345678e8_q_m) == "1.23457e+08");
+    CHECK(fmt::format("{:%.3gQ}", 1.2345678_q_m) == "1.23");
+    CHECK(fmt::format("{:%.3gQ}", 1.2345678e8_q_m) == "1.23e+08");
+    CHECK(fmt::format("{:%GQ}",   1.2345678_q_m) == "1.23457");
+    CHECK(fmt::format("{:%GQ}",   1.2345678e8_q_m) == "1.23457E+08");
+    CHECK(fmt::format("{:%.3GQ}", 1.2345678_q_m) == "1.23");
+    CHECK(fmt::format("{:%.3GQ}", 1.2345678e8_q_m) == "1.23E+08");
   }
 }
 
@@ -1118,20 +1118,20 @@ TEST_CASE("different base types with the # specifier")
 {
   SECTION("full format {:%Q %q} on a quantity")
   {
-    CHECK(fmt::format("{:%#bQ %q}", 42q_m) == "0b101010 m");
-    CHECK(fmt::format("{:%#BQ %q}", 42q_m) == "0B101010 m");
-    CHECK(fmt::format("{:%#oQ %q}", 42q_m) == "052 m");
-    CHECK(fmt::format("{:%#xQ %q}", 42q_m) == "0x2a m");
-    CHECK(fmt::format("{:%#XQ %q}", 42q_m) == "0X2A m");
+    CHECK(fmt::format("{:%#bQ %q}", 42_q_m) == "0b101010 m");
+    CHECK(fmt::format("{:%#BQ %q}", 42_q_m) == "0B101010 m");
+    CHECK(fmt::format("{:%#oQ %q}", 42_q_m) == "052 m");
+    CHECK(fmt::format("{:%#xQ %q}", 42_q_m) == "0x2a m");
+    CHECK(fmt::format("{:%#XQ %q}", 42_q_m) == "0X2A m");
   }
 
   SECTION("value only format {:%Q} on a quantity")
   {
-    CHECK(fmt::format("{:%#bQ}", 42q_m) == "0b101010");
-    CHECK(fmt::format("{:%#BQ}", 42q_m) == "0B101010");
-    CHECK(fmt::format("{:%#oQ}", 42q_m) == "052");
-    CHECK(fmt::format("{:%#xQ}", 42q_m) == "0x2a");
-    CHECK(fmt::format("{:%#XQ}", 42q_m) == "0X2A");
+    CHECK(fmt::format("{:%#bQ}", 42_q_m) == "0b101010");
+    CHECK(fmt::format("{:%#BQ}", 42_q_m) == "0B101010");
+    CHECK(fmt::format("{:%#oQ}", 42_q_m) == "052");
+    CHECK(fmt::format("{:%#xQ}", 42_q_m) == "0x2a");
+    CHECK(fmt::format("{:%#XQ}", 42_q_m) == "0X2A");
   }
 }
 
@@ -1141,7 +1141,7 @@ TEST_CASE("quantity_cast", "[text][ostream]")
 
   SECTION("int to double representation")
   {
-    const auto q = 121q_km / 2q_h;
+    const auto q = 121_q_km / 2_q_h;
 
     SECTION("original")
     {
@@ -1164,7 +1164,7 @@ TEST_CASE("quantity_cast", "[text][ostream]")
 
   SECTION("double to int representation")
   {
-    const auto q = 121.q_km / 2q_h;
+    const auto q = 121._q_km / 2_q_h;
 
     SECTION("original")
     {
diff --git a/test/unit_test/runtime/fmt_units_test.cpp b/test/unit_test/runtime/fmt_units_test.cpp
index 4b15807a..178d1742 100644
--- a/test/unit_test/runtime/fmt_units_test.cpp
+++ b/test/unit_test/runtime/fmt_units_test.cpp
@@ -43,278 +43,278 @@ TEST_CASE("fmt::format on synthesized unit symbols", "[text][fmt]")
 {
   SECTION("time")
   {
-    CHECK(fmt::format("{}", 1q_ns) == "1 ns");
-    CHECK(fmt::format("{}", 1q_us) == "1 µs");
-    CHECK(fmt::format("{}", 1q_ms) == "1 ms");
+    CHECK(fmt::format("{}", 1_q_ns) == "1 ns");
+    CHECK(fmt::format("{}", 1_q_us) == "1 µs");
+    CHECK(fmt::format("{}", 1_q_ms) == "1 ms");
 
-    CHECK(fmt::format("{:%Q %Aq}", 1q_us) == "1 us");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_us) == "1 us");
   }
 
   SECTION("length")
   {
-    CHECK(fmt::format("{}", 1q_mm) == "1 mm");
-    CHECK(fmt::format("{}", 1q_cm) == "1 cm");
-    CHECK(fmt::format("{}", 1q_km) == "1 km");
-    CHECK(fmt::format("{}", 1q_ft) == "1 ft");
-    CHECK(fmt::format("{}", 1q_ft_us) == "1 ft(us)");
-    CHECK(fmt::format("{}", 1q_yd) == "1 yd");
-    CHECK(fmt::format("{}", 1q_in) == "1 in");
-    CHECK(fmt::format("{}", 1q_fathom) == "1 fathom");
-    CHECK(fmt::format("{}", 1q_fathom_us) == "1 fathom(us)");
-    CHECK(fmt::format("{}", 1q_mi) == "1 mi");
-    CHECK(fmt::format("{}", 1q_mi_us) == "1 mi(us)");
-    CHECK(fmt::format("{}", 1q_naut_mi) == "1 mi(naut)");
-    CHECK(fmt::format("{}", 1q_ch) == "1 ch");
-    CHECK(fmt::format("{}", 1q_rd) == "1 rd");
-    CHECK(fmt::format("{}", 1q_thou) == "1 thou");
-    CHECK(fmt::format("{}", 1q_pc) == "1 pc");
-    CHECK(fmt::format("{}", 1q_ly) == "1 ly");
-    CHECK(fmt::format("{}", 1q_pc) == "1 pc");
-    CHECK(fmt::format("{}", 1q_angstrom) == "1 angstrom");
-    CHECK(fmt::format("{}", 1q_au) == "1 au");
-    CHECK(fmt::format("{}", 1q_pica_comp) == "1 pica(comp)");
-    CHECK(fmt::format("{}", 1q_pica_prn) == "1 pica(prn)");
-    CHECK(fmt::format("{}", 1q_point_comp) == "1 point(comp)");
-    CHECK(fmt::format("{}", 1q_point_prn) == "1 point(prn)");
+    CHECK(fmt::format("{}", 1_q_mm) == "1 mm");
+    CHECK(fmt::format("{}", 1_q_cm) == "1 cm");
+    CHECK(fmt::format("{}", 1_q_km) == "1 km");
+    CHECK(fmt::format("{}", 1_q_ft) == "1 ft");
+    CHECK(fmt::format("{}", 1_q_ft_us) == "1 ft(us)");
+    CHECK(fmt::format("{}", 1_q_yd) == "1 yd");
+    CHECK(fmt::format("{}", 1_q_in) == "1 in");
+    CHECK(fmt::format("{}", 1_q_fathom) == "1 fathom");
+    CHECK(fmt::format("{}", 1_q_fathom_us) == "1 fathom(us)");
+    CHECK(fmt::format("{}", 1_q_mi) == "1 mi");
+    CHECK(fmt::format("{}", 1_q_mi_us) == "1 mi(us)");
+    CHECK(fmt::format("{}", 1_q_naut_mi) == "1 mi(naut)");
+    CHECK(fmt::format("{}", 1_q_ch) == "1 ch");
+    CHECK(fmt::format("{}", 1_q_rd) == "1 rd");
+    CHECK(fmt::format("{}", 1_q_thou) == "1 thou");
+    CHECK(fmt::format("{}", 1_q_pc) == "1 pc");
+    CHECK(fmt::format("{}", 1_q_ly) == "1 ly");
+    CHECK(fmt::format("{}", 1_q_pc) == "1 pc");
+    CHECK(fmt::format("{}", 1_q_angstrom) == "1 angstrom");
+    CHECK(fmt::format("{}", 1_q_au) == "1 au");
+    CHECK(fmt::format("{}", 1_q_pica_comp) == "1 pica(comp)");
+    CHECK(fmt::format("{}", 1_q_pica_prn) == "1 pica(prn)");
+    CHECK(fmt::format("{}", 1_q_point_comp) == "1 point(comp)");
+    CHECK(fmt::format("{}", 1_q_point_prn) == "1 point(prn)");
   }
 
   SECTION("mass")
   {
-    CHECK(fmt::format("{}", 1q_kg) == "1 kg");
+    CHECK(fmt::format("{}", 1_q_kg) == "1 kg");
   }
 
   SECTION("area")
   {
-    CHECK(fmt::format("{}", 1q_m2) == "1 m²");
-    CHECK(fmt::format("{}", 1q_mm2) == "1 mm²");
-    CHECK(fmt::format("{}", 1q_cm2) == "1 cm²");
-    CHECK(fmt::format("{}", 1q_km2) == "1 km²");
-    CHECK(fmt::format("{}", 1q_ft2) == "1 ft²");
+    CHECK(fmt::format("{}", 1_q_m2) == "1 m²");
+    CHECK(fmt::format("{}", 1_q_mm2) == "1 mm²");
+    CHECK(fmt::format("{}", 1_q_cm2) == "1 cm²");
+    CHECK(fmt::format("{}", 1_q_km2) == "1 km²");
+    CHECK(fmt::format("{}", 1_q_ft2) == "1 ft²");
 
-    CHECK(fmt::format("{:%Q %Aq}", 1q_m2) == "1 m^2");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_mm2) == "1 mm^2");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_cm2) == "1 cm^2");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_km2) == "1 km^2");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_ft2) == "1 ft^2");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_m2) == "1 m^2");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_mm2) == "1 mm^2");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_cm2) == "1 cm^2");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_km2) == "1 km^2");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_ft2) == "1 ft^2");
   }
 
   SECTION("density")
   {
-      CHECK(fmt::format("{}", 1q_kg_per_m3) == "1 kg/m³");
-      CHECK(fmt::format("{:%Q %Aq}", 1q_kg_per_m3) == "1 kg/m^3");
+      CHECK(fmt::format("{}", 1_q_kg_per_m3) == "1 kg/m³");
+      CHECK(fmt::format("{:%Q %Aq}", 1_q_kg_per_m3) == "1 kg/m^3");
   }
 
   SECTION("resistance")
   {
-    CHECK(fmt::format("{}", 1q_R) == "1 Ω");
-    CHECK(fmt::format("{}", 1q_kR) == "1 kΩ");
-    CHECK(fmt::format("{}", 1q_mR) == "1 mΩ");
-    CHECK(fmt::format("{}", 1q_MR) == "1 MΩ");
+    CHECK(fmt::format("{}", 1_q_R) == "1 Ω");
+    CHECK(fmt::format("{}", 1_q_kR) == "1 kΩ");
+    CHECK(fmt::format("{}", 1_q_mR) == "1 mΩ");
+    CHECK(fmt::format("{}", 1_q_MR) == "1 MΩ");
 
-    CHECK(fmt::format("{:%Q %Aq}", 1q_R) == "1 ohm");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_kR) == "1 kohm");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_mR) == "1 mohm");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_MR) == "1 Mohm");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_R) == "1 ohm");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_kR) == "1 kohm");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_mR) == "1 mohm");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_MR) == "1 Mohm");
   }
 
   SECTION("voltage")
   {
-     CHECK(fmt::format("{}", 1q_V) == "1 V");
-     CHECK(fmt::format("{}", 1q_mV) == "1 mV");
-     CHECK(fmt::format("{}", 1q_uV) == "1 µV");
-     CHECK(fmt::format("{}", 1q_nV) == "1 nV");
-     CHECK(fmt::format("{}", 1q_pV) == "1 pV");
+     CHECK(fmt::format("{}", 1_q_V) == "1 V");
+     CHECK(fmt::format("{}", 1_q_mV) == "1 mV");
+     CHECK(fmt::format("{}", 1_q_uV) == "1 µV");
+     CHECK(fmt::format("{}", 1_q_nV) == "1 nV");
+     CHECK(fmt::format("{}", 1_q_pV) == "1 pV");
 
-     CHECK(fmt::format("{:%Q %Aq}", 1q_uV) == "1 uV");
+     CHECK(fmt::format("{:%Q %Aq}", 1_q_uV) == "1 uV");
   }
 
   SECTION("volume")
   {
-    CHECK(fmt::format("{}", 1q_m3) == "1 m³");
-    CHECK(fmt::format("{}", 1q_mm3) == "1 mm³");
-    CHECK(fmt::format("{}", 1q_cm3) == "1 cm³");
-    CHECK(fmt::format("{}", 1q_km3) == "1 km³");
-    CHECK(fmt::format("{}", 1q_ft3) == "1 ft³");
+    CHECK(fmt::format("{}", 1_q_m3) == "1 m³");
+    CHECK(fmt::format("{}", 1_q_mm3) == "1 mm³");
+    CHECK(fmt::format("{}", 1_q_cm3) == "1 cm³");
+    CHECK(fmt::format("{}", 1_q_km3) == "1 km³");
+    CHECK(fmt::format("{}", 1_q_ft3) == "1 ft³");
 
-    CHECK(fmt::format("{:%Q %Aq}", 1q_m3) == "1 m^3");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_mm3) == "1 mm^3");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_cm3) == "1 cm^3");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_km3) == "1 km^3");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_ft3) == "1 ft^3");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_m3) == "1 m^3");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_mm3) == "1 mm^3");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_cm3) == "1 cm^3");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_km3) == "1 km^3");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_ft3) == "1 ft^3");
   }
 
   SECTION("frequency")
   {
-    CHECK(fmt::format("{}", 1q_mHz) == "1 mHz");
-    CHECK(fmt::format("{}", 1q_kHz) == "1 kHz");
-    CHECK(fmt::format("{}", 1q_MHz) == "1 MHz");
-    CHECK(fmt::format("{}", 1q_GHz) == "1 GHz");
-    CHECK(fmt::format("{}", 1q_THz) == "1 THz");
+    CHECK(fmt::format("{}", 1_q_mHz) == "1 mHz");
+    CHECK(fmt::format("{}", 1_q_kHz) == "1 kHz");
+    CHECK(fmt::format("{}", 1_q_MHz) == "1 MHz");
+    CHECK(fmt::format("{}", 1_q_GHz) == "1 GHz");
+    CHECK(fmt::format("{}", 1_q_THz) == "1 THz");
   }
 
   SECTION("speed")
   {
-    CHECK(fmt::format("{}", 1q_m_per_s) == "1 m/s");
-    CHECK(fmt::format("{}", 1q_km_per_h) == "1 km/h");
-    CHECK(fmt::format("{}", 1q_mi_per_h) == "1 mi/h");
+    CHECK(fmt::format("{}", 1_q_m_per_s) == "1 m/s");
+    CHECK(fmt::format("{}", 1_q_km_per_h) == "1 km/h");
+    CHECK(fmt::format("{}", 1_q_mi_per_h) == "1 mi/h");
   }
 
   SECTION("acceleration")
   {
-    CHECK(fmt::format("{}", 1q_m_per_s2) == "1 m/s²");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_m_per_s2) == "1 m/s^2");
+    CHECK(fmt::format("{}", 1_q_m_per_s2) == "1 m/s²");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_m_per_s2) == "1 m/s^2");
   }
 
   SECTION("momentum")
   {
-    CHECK(fmt::format("{}", 1q_kg_m_per_s) == "1 kg ⋅ m/s");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_kg_m_per_s) == "1 kg m/s");
+    CHECK(fmt::format("{}", 1_q_kg_m_per_s) == "1 kg ⋅ m/s");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_kg_m_per_s) == "1 kg m/s");
   }
 
   SECTION("energy")
   {
-    CHECK(fmt::format("{}", 1q_mJ) == "1 mJ");
-    CHECK(fmt::format("{}", 1q_kJ) == "1 kJ");
-    CHECK(fmt::format("{}", 1q_MJ) == "1 MJ");
-    CHECK(fmt::format("{}", 1q_GJ) == "1 GJ");
+    CHECK(fmt::format("{}", 1_q_mJ) == "1 mJ");
+    CHECK(fmt::format("{}", 1_q_kJ) == "1 kJ");
+    CHECK(fmt::format("{}", 1_q_MJ) == "1 MJ");
+    CHECK(fmt::format("{}", 1_q_GJ) == "1 GJ");
   }
 
   SECTION("power")
   {
-    CHECK(fmt::format("{}", 1q_mW) == "1 mW");
-    CHECK(fmt::format("{}", 1q_kW) == "1 kW");
-    CHECK(fmt::format("{}", 1q_MW) == "1 MW");
-    CHECK(fmt::format("{}", 1q_GW) == "1 GW");
+    CHECK(fmt::format("{}", 1_q_mW) == "1 mW");
+    CHECK(fmt::format("{}", 1_q_kW) == "1 kW");
+    CHECK(fmt::format("{}", 1_q_MW) == "1 MW");
+    CHECK(fmt::format("{}", 1_q_GW) == "1 GW");
   }
 
   SECTION("surface tension")
   {
-    CHECK(fmt::format("{}", 1q_N_per_m) == "1 N/m");
+    CHECK(fmt::format("{}", 1_q_N_per_m) == "1 N/m");
   }
 
   SECTION("magnetic induction")
   {
-    CHECK(fmt::format("{}", 1q_T) == "1 T");
+    CHECK(fmt::format("{}", 1_q_T) == "1 T");
   }
 
   SECTION("magnetic flux")
   {
-    CHECK(fmt::format("{}", 1q_Wb) == "1 Wb");
-    CHECK(fmt::format("{}", 1q_G) == "1 G");
+    CHECK(fmt::format("{}", 1_q_Wb) == "1 Wb");
+    CHECK(fmt::format("{}", 1_q_G) == "1 G");
   }
 
   SECTION("inductance")
   {
-    CHECK(fmt::format("{}", 1q_H) == "1 H");
-    CHECK(fmt::format("{}", 1q_mH) == "1 mH");
+    CHECK(fmt::format("{}", 1_q_H) == "1 H");
+    CHECK(fmt::format("{}", 1_q_mH) == "1 mH");
   }
 
   SECTION("conductance")
   {
-    CHECK(fmt::format("{}", 1q_S) == "1 S");
-    CHECK(fmt::format("{}", 1q_nS) == "1 nS");
+    CHECK(fmt::format("{}", 1_q_S) == "1 S");
+    CHECK(fmt::format("{}", 1_q_nS) == "1 nS");
   }
 
   SECTION("catalytic activity")
   {
-    CHECK(fmt::format("{}", 1q_kat) == "1 kat");
-    CHECK(fmt::format("{}", 1q_U) == "1 U");
+    CHECK(fmt::format("{}", 1_q_kat) == "1 kat");
+    CHECK(fmt::format("{}", 1_q_U) == "1 U");
   }
 
   SECTION("absorbed dose")
   {
-    CHECK(fmt::format("{}", 1q_Gy) == "1 Gy");
-    CHECK(fmt::format("{}", 1q_kGy) == "1 kGy");
-    CHECK(fmt::format("{}", 1q_mGy) == "1 mGy");
+    CHECK(fmt::format("{}", 1_q_Gy) == "1 Gy");
+    CHECK(fmt::format("{}", 1_q_kGy) == "1 kGy");
+    CHECK(fmt::format("{}", 1_q_mGy) == "1 mGy");
   }
 
   SECTION("addition with common ratio")
   {
-    CHECK(fmt::format("{}", 1q_in + 1q_yd) == "37 in");
+    CHECK(fmt::format("{}", 1_q_in + 1_q_yd) == "37 in");
   }
 
   SECTION("current density")
   {
-    CHECK(fmt::format("{}", 1q_A_per_m2) == "1 A/m²");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_A_per_m2) == "1 A/m^2");
+    CHECK(fmt::format("{}", 1_q_A_per_m2) == "1 A/m²");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_A_per_m2) == "1 A/m^2");
   }
 
   SECTION("concentration")
   {
-    CHECK(fmt::format("{}", 1q_mol_per_m3) == "1 mol/m³");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_mol_per_m3) == "1 mol/m^3");
+    CHECK(fmt::format("{}", 1_q_mol_per_m3) == "1 mol/m³");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_mol_per_m3) == "1 mol/m^3");
   }
 
   SECTION("luminance")
   {
-    CHECK(fmt::format("{}", 1q_cd_per_m2) == "1 cd/m²");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_cd_per_m2) == "1 cd/m^2");
+    CHECK(fmt::format("{}", 1_q_cd_per_m2) == "1 cd/m²");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_cd_per_m2) == "1 cd/m^2");
   }
 
   SECTION("dynamic viscosity")
   {
-    CHECK(fmt::format("{}", 1q_Pa_s) == "1 Pa ⋅ s");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_Pa_s) == "1 Pa s");
+    CHECK(fmt::format("{}", 1_q_Pa_s) == "1 Pa ⋅ s");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_Pa_s) == "1 Pa s");
   }
 
   SECTION("heat capacity")
   {
-    CHECK(fmt::format("{}", 1q_J_per_K) == "1 J/K");
+    CHECK(fmt::format("{}", 1_q_J_per_K) == "1 J/K");
   }
 
   SECTION("specific heat capacity")
   {
-    CHECK(fmt::format("{}", 1q_J_per_kg_K) == "1 J ⋅ K⁻¹ ⋅ kg⁻¹");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_J_per_kg_K) == "1 J K^-1 kg^-1");
+    CHECK(fmt::format("{}", 1_q_J_per_kg_K) == "1 J ⋅ K⁻¹ ⋅ kg⁻¹");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_J_per_kg_K) == "1 J K^-1 kg^-1");
   }
 
   SECTION("molar heath capacity")
   {
-    CHECK(fmt::format("{}", 1q_J_per_mol_K) == "1 J ⋅ K⁻¹ ⋅ mol⁻¹");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_J_per_mol_K) == "1 J K^-1 mol^-1");
+    CHECK(fmt::format("{}", 1_q_J_per_mol_K) == "1 J ⋅ K⁻¹ ⋅ mol⁻¹");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_J_per_mol_K) == "1 J K^-1 mol^-1");
   }
 
   SECTION("thermal conductivity")
   {
-    CHECK(fmt::format("{}", 1q_W_per_m_K) == "1 W ⋅ m⁻¹ ⋅ K⁻¹");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_W_per_m_K) == "1 W m^-1 K^-1");
+    CHECK(fmt::format("{}", 1_q_W_per_m_K) == "1 W ⋅ m⁻¹ ⋅ K⁻¹");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_W_per_m_K) == "1 W m^-1 K^-1");
   }
 
   SECTION("electric field strength")
   {
-    CHECK(fmt::format("{}", 1q_V_per_m) == "1 V/m");
+    CHECK(fmt::format("{}", 1_q_V_per_m) == "1 V/m");
   }
 
   SECTION("charge density")
   {
-    CHECK(fmt::format("{}", 1q_C_per_m3) == "1 C/m³");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_C_per_m3) == "1 C/m^3");
-    CHECK(fmt::format("{}", 1q_C_per_m2) == "1 C/m²");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_C_per_m2) == "1 C/m^2");
+    CHECK(fmt::format("{}", 1_q_C_per_m3) == "1 C/m³");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_C_per_m3) == "1 C/m^3");
+    CHECK(fmt::format("{}", 1_q_C_per_m2) == "1 C/m²");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_C_per_m2) == "1 C/m^2");
   }
 
   SECTION("permittivity")
   {
-    CHECK(fmt::format("{}", 1q_F_per_m) == "1 F/m");
+    CHECK(fmt::format("{}", 1_q_F_per_m) == "1 F/m");
   }
 
   SECTION("permeability")
   {
-    CHECK(fmt::format("{}", 1q_H_per_m) == "1 H/m");
+    CHECK(fmt::format("{}", 1_q_H_per_m) == "1 H/m");
   }
 
   SECTION("molar energy")
   {
-    CHECK(fmt::format("{}", 1q_J_per_mol) == "1 J/mol");
+    CHECK(fmt::format("{}", 1_q_J_per_mol) == "1 J/mol");
   }
 
   SECTION("incoherent units with powers")
   {
-    CHECK(fmt::format("{}", 1q_mi * 1q_mi * 1q_mi) == "1 [15900351812136/3814697265625 × 10⁹] m³");
-    CHECK(fmt::format("{}", 1q_au * 1q_au) == "1 [2237952291797391849 × 10⁴] m²");
+    CHECK(fmt::format("{}", 1_q_mi * 1_q_mi * 1_q_mi) == "1 [15900351812136/3814697265625 × 10⁹] m³");
+    CHECK(fmt::format("{}", 1_q_au * 1_q_au) == "1 [2237952291797391849 × 10⁴] m²");
 
-    CHECK(fmt::format("{:%Q %Aq}", 1q_mi * 1q_mi * 1q_mi) == "1 [15900351812136/3814697265625 x 10^9] m^3");
-    CHECK(fmt::format("{:%Q %Aq}", 1q_au * 1q_au) == "1 [2237952291797391849 x 10^4] m^2");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_mi * 1_q_mi * 1_q_mi) == "1 [15900351812136/3814697265625 x 10^9] m^3");
+    CHECK(fmt::format("{:%Q %Aq}", 1_q_au * 1_q_au) == "1 [2237952291797391849 x 10^4] m^2");
   }
 
   SECTION("unknown scaled unit with reference different than the dimension's coherent unit")
diff --git a/test/unit_test/runtime/math_test.cpp b/test/unit_test/runtime/math_test.cpp
index 6b0c0243..1b73f46a 100644
--- a/test/unit_test/runtime/math_test.cpp
+++ b/test/unit_test/runtime/math_test.cpp
@@ -33,25 +33,25 @@ using namespace units::physical::si;
 TEST_CASE("'pow<N>()' on quantity changes the value and the dimension accordingly", "[math][pow]")
 {
   SECTION ("'pow<0>(q)' returns '1'") {
-    CHECK(pow<0>(2q_m) == 1);
+    CHECK(pow<0>(2_q_m) == 1);
   }
 
   SECTION ("'pow<1>(q)' returns 'q'") {
-    CHECK(pow<1>(2q_m) == 2q_m);
+    CHECK(pow<1>(2_q_m) == 2_q_m);
   }
 
   SECTION ("'pow<2>(q)' squares both the value and a dimension") {
-    CHECK(pow<2>(2q_m) == 4q_m2);
+    CHECK(pow<2>(2_q_m) == 4_q_m2);
   }
 
   SECTION ("'pow<3>(q)' cubes both the value and a dimension") {
-    CHECK(pow<3>(2q_m) == 8q_m3);
+    CHECK(pow<3>(2_q_m) == 8_q_m3);
   }
 }
 
 TEST_CASE("'sqrt()' on quantity changes the value and the dimension accordingly", "[math][sqrt]")
 {
-  REQUIRE(sqrt(4q_m2) == 2q_m);
+  REQUIRE(sqrt(4_q_m2) == 2_q_m);
 }
 
 TEST_CASE("absolute functions on quantity returns the absolute value", "[math][abs][fabs]")
@@ -60,13 +60,13 @@ TEST_CASE("absolute functions on quantity returns the absolute value", "[math][a
   {
     SECTION ("integral representation")
     {
-      REQUIRE(abs(-1q_m) == 1q_m);
+      REQUIRE(abs(-1_q_m) == 1_q_m);
     }
 
 #ifndef COMP_MSVC
     SECTION ("floating-point representation")
     {
-      REQUIRE(abs(-1.q_m) == 1q_m);
+      REQUIRE(abs(-1._q_m) == 1_q_m);
     }
 #endif
   }
@@ -75,13 +75,13 @@ TEST_CASE("absolute functions on quantity returns the absolute value", "[math][a
   {
     SECTION ("integral representation")
     {
-      REQUIRE(abs(1q_m) == 1q_m);
+      REQUIRE(abs(1_q_m) == 1_q_m);
     }
 
 #ifndef COMP_MSVC
     SECTION ("floating-point representation")
     {
-      REQUIRE(abs(1.q_m) == 1q_m);
+      REQUIRE(abs(1._q_m) == 1_q_m);
     }
 #endif
   }
@@ -90,12 +90,12 @@ TEST_CASE("absolute functions on quantity returns the absolute value", "[math][a
 TEST_CASE("numeric_limits functions", "[limits]")
 {
   SECTION ("'epsilon' works as expected using default floating type") {
-    REQUIRE(epsilon<decltype(1.q_m)>().count() == std::numeric_limits<decltype(1.q_m)::rep>::epsilon());
+    REQUIRE(epsilon<decltype(1._q_m)>().count() == std::numeric_limits<decltype(1._q_m)::rep>::epsilon());
   }
   SECTION ("'epsilon' works as expected using integers") {
-    REQUIRE(epsilon<decltype(1q_m)>().count() == std::numeric_limits<decltype(1q_m)::rep>::epsilon());
+    REQUIRE(epsilon<decltype(1_q_m)>().count() == std::numeric_limits<decltype(1_q_m)::rep>::epsilon());
   }
   SECTION ("'epsilon' works as expected using mixed Rep types") {
-    REQUIRE(epsilon<decltype(1q_m)>().count() != std::numeric_limits<decltype(1.q_m)::rep>::epsilon());
+    REQUIRE(epsilon<decltype(1_q_m)>().count() != std::numeric_limits<decltype(1._q_m)::rep>::epsilon());
   }
 }
diff --git a/test/unit_test/static/cgs_test.cpp b/test/unit_test/static/cgs_test.cpp
index 8cdd0540..85348405 100644
--- a/test/unit_test/static/cgs_test.cpp
+++ b/test/unit_test/static/cgs_test.cpp
@@ -50,17 +50,17 @@ static_assert(centimetre::symbol == "cm");
 
 // speed
 
-static_assert(10q_cm / 5q_s == 2q_cm_per_s);
-static_assert(10q_cm / 2q_cm_per_s == 5q_s);
-static_assert(10q_cm == 2q_cm_per_s * 5q_s);
+static_assert(10_q_cm / 5_q_s == 2_q_cm_per_s);
+static_assert(10_q_cm / 2_q_cm_per_s == 5_q_s);
+static_assert(10_q_cm == 2_q_cm_per_s * 5_q_s);
 
 static_assert(detail::unit_text<dim_speed, centimetre_per_second>() == "cm/s");
 
 // area
 static_assert(centimetre::ratio / dimension_unit<dim_length>::ratio == ratio(1));
 
-static_assert(1q_cm * 1q_cm == 1q_cm2);
-static_assert(100q_cm2 / 10q_cm == 10q_cm);
+static_assert(1_q_cm * 1_q_cm == 1_q_cm2);
+static_assert(100_q_cm2 / 10_q_cm == 10_q_cm);
 
 static_assert(detail::unit_text<dim_area, square_centimetre>() == basic_symbol_text("cm²", "cm^2"));
 
@@ -68,35 +68,35 @@ static_assert(detail::unit_text<dim_area, square_centimetre>() == basic_symbol_t
 
 // acceleration
 
-static_assert(10q_cm_per_s / 10q_s == 1q_Gal);
-static_assert(10q_cm_per_s / 1q_Gal == 10q_s);
-static_assert(1q_Gal * 10q_s == 10q_cm_per_s);
+static_assert(10_q_cm_per_s / 10_q_s == 1_q_Gal);
+static_assert(10_q_cm_per_s / 1_q_Gal == 10_q_s);
+static_assert(1_q_Gal * 10_q_s == 10_q_cm_per_s);
 
 // force
 
-static_assert(10q_g * 10q_Gal == 100q_dyn);
-static_assert(100q_dyn / 10q_g == 10q_Gal);
-static_assert(100q_dyn / 10q_Gal == 10q_g);
+static_assert(10_q_g * 10_q_Gal == 100_q_dyn);
+static_assert(100_q_dyn / 10_q_g == 10_q_Gal);
+static_assert(100_q_dyn / 10_q_Gal == 10_q_g);
 
 // pressure
 
-static_assert(10q_dyn / 10q_cm2 == 1q_Ba);
-static_assert(10q_dyn / 1q_Ba == 10q_cm2);
-static_assert(1q_Ba * 10q_cm2 == 10q_dyn);
+static_assert(10_q_dyn / 10_q_cm2 == 1_q_Ba);
+static_assert(10_q_dyn / 1_q_Ba == 10_q_cm2);
+static_assert(1_q_Ba * 10_q_cm2 == 10_q_dyn);
 
 // energy
 
-static_assert(10q_dyn * 10q_cm == 100q_erg);
-static_assert(100q_erg / 10q_cm == 10q_dyn);
-static_assert(100q_erg / 10q_dyn == 10q_cm);
+static_assert(10_q_dyn * 10_q_cm == 100_q_erg);
+static_assert(100_q_erg / 10_q_cm == 10_q_dyn);
+static_assert(100_q_erg / 10_q_dyn == 10_q_cm);
 
 /* ************** DERIVED DIMENSIONS IN TERMS OF OTHER UNITS **************** */
 
 // power
 
-static_assert(10q_erg / 10q_s == 1q_erg_per_s);
-static_assert(1q_erg_per_s * 10q_s == 10q_erg);
-static_assert(10q_erg / 1q_erg_per_s == 10q_s);
+static_assert(10_q_erg / 10_q_s == 1_q_erg_per_s);
+static_assert(1_q_erg_per_s * 10_q_s == 10_q_erg);
+static_assert(10_q_erg / 1_q_erg_per_s == 10_q_s);
 
 static_assert(detail::unit_text<dim_power, erg_per_second>() == "erg/s");
 
diff --git a/test/unit_test/static/custom_unit_test.cpp b/test/unit_test/static/custom_unit_test.cpp
index bd396f4a..f513ffae 100644
--- a/test/unit_test/static/custom_unit_test.cpp
+++ b/test/unit_test/static/custom_unit_test.cpp
@@ -62,7 +62,7 @@ namespace {
 struct kilogram_per_second : unit<kilogram_per_second> {};
 struct dim_mass_rate : derived_dimension<dim_mass_rate, kilogram_per_second, units::exponent<dim_mass, 1>, units::exponent<dim_time, -1>> {};
 struct kilogram_per_hour : deduced_unit<kilogram_per_hour, dim_mass_rate, kilogram, hour> {};
-constexpr auto a = 1q_kg / 1q_h;
+constexpr auto a = 1_q_kg / 1_q_h;
 static_assert(is_same_v<decltype(a)::unit, kilogram_per_hour>);
 
 }
diff --git a/test/unit_test/static/data_test.cpp b/test/unit_test/static/data_test.cpp
index 75ce5d86..c7d31751 100644
--- a/test/unit_test/static/data_test.cpp
+++ b/test/unit_test/static/data_test.cpp
@@ -31,17 +31,17 @@ using namespace units::data;
 
 // information
 
-static_assert(1q_B == 8q_b);
-static_assert(1024q_b == 1q_Kib);
-static_assert(1024q_B == 1q_KiB);
-static_assert(8 * 1024q_b == 1q_KiB);
-static_assert(8 * 1q_Kib == 1q_KiB);
+static_assert(1_q_B == 8_q_b);
+static_assert(1024_q_b == 1_q_Kib);
+static_assert(1024_q_B == 1_q_KiB);
+static_assert(8 * 1024_q_b == 1_q_KiB);
+static_assert(8 * 1_q_Kib == 1_q_KiB);
 
-static_assert(1q_Kib == 1024q_b);
-static_assert(1q_Mib == 1024q_Kib);
-static_assert(1q_Gib == 1024q_Mib);
-static_assert(1q_Tib == 1024q_Gib);
-static_assert(1q_Pib == 1024q_Tib);
+static_assert(1_q_Kib == 1024_q_b);
+static_assert(1_q_Mib == 1024_q_Kib);
+static_assert(1_q_Gib == 1024_q_Mib);
+static_assert(1_q_Tib == 1024_q_Gib);
+static_assert(1_q_Pib == 1024_q_Tib);
 
 // bitrate
 
diff --git a/test/unit_test/static/fps_test.cpp b/test/unit_test/static/fps_test.cpp
index d1e575b7..fc34dfa0 100644
--- a/test/unit_test/static/fps_test.cpp
+++ b/test/unit_test/static/fps_test.cpp
@@ -50,17 +50,17 @@ static_assert(foot::symbol == "ft");
 
 // speed
 
-static_assert(10q_ft / 5q_s == 2q_ft_per_s);
-static_assert(10q_ft / 2q_ft_per_s == 5q_s);
-static_assert(10q_ft == 2q_ft_per_s * 5q_s);
+static_assert(10_q_ft / 5_q_s == 2_q_ft_per_s);
+static_assert(10_q_ft / 2_q_ft_per_s == 5_q_s);
+static_assert(10_q_ft == 2_q_ft_per_s * 5_q_s);
 
 static_assert(detail::unit_text<dim_speed, foot_per_second>() == "ft/s");
 
 // area
 static_assert(foot::ratio / dimension_unit<dim_length>::ratio == ratio(1));
 
-static_assert(1q_ft * 1q_ft == 1q_ft2);
-static_assert(100q_ft2 / 10q_ft == 10q_ft);
+static_assert(1_q_ft * 1_q_ft == 1_q_ft2);
+static_assert(100_q_ft2 / 10_q_ft == 10_q_ft);
 
 static_assert(detail::unit_text<dim_area, square_foot>() == basic_symbol_text("ft²", "ft^2"));
 
@@ -68,34 +68,34 @@ static_assert(detail::unit_text<dim_area, square_foot>() == basic_symbol_text("f
 
 // acceleration
 
-static_assert(10q_ft_per_s / 10q_s == 1q_ft_per_s2);
-static_assert(10q_ft_per_s / 1q_ft_per_s2 == 10q_s);
-static_assert(1q_ft_per_s2 * 10q_s == 10q_ft_per_s);
+static_assert(10_q_ft_per_s / 10_q_s == 1_q_ft_per_s2);
+static_assert(10_q_ft_per_s / 1_q_ft_per_s2 == 10_q_s);
+static_assert(1_q_ft_per_s2 * 10_q_s == 10_q_ft_per_s);
 
 // force
 
-static_assert(10q_lb * 10q_ft_per_s2 == 100q_pdl);
-static_assert(100q_pdl / 10q_lb == 10q_ft_per_s2);
-static_assert(100q_pdl / 10q_ft_per_s2 == 10q_lb);
+static_assert(10_q_lb * 10_q_ft_per_s2 == 100_q_pdl);
+static_assert(100_q_pdl / 10_q_lb == 10_q_ft_per_s2);
+static_assert(100_q_pdl / 10_q_ft_per_s2 == 10_q_lb);
 
 // pressure
-static_assert(10q_pdl / 10q_ft2 == 1q_pdl_per_ft2);
-static_assert(10q_pdl / 1q_pdl_per_ft2 == 10q_ft2);
-static_assert(1q_pdl_per_ft2 * 10q_ft2 == 10q_pdl);
+static_assert(10_q_pdl / 10_q_ft2 == 1_q_pdl_per_ft2);
+static_assert(10_q_pdl / 1_q_pdl_per_ft2 == 10_q_ft2);
+static_assert(1_q_pdl_per_ft2 * 10_q_ft2 == 10_q_pdl);
 
 // energy
 
-static_assert(10q_pdl * 10q_ft == 100q_ft_pdl);
-static_assert(100q_ft_pdl / 10q_ft == 10q_pdl);
-static_assert(100q_ft_pdl / 10q_pdl == 10q_ft);
+static_assert(10_q_pdl * 10_q_ft == 100_q_ft_pdl);
+static_assert(100_q_ft_pdl / 10_q_ft == 10_q_pdl);
+static_assert(100_q_ft_pdl / 10_q_pdl == 10_q_ft);
 
 /* ************** DERIVED DIMENSIONS IN TERMS OF OTHER UNITS **************** */
 
 // power
 
-static_assert(10q_ft_pdl / 10q_s == 1q_ft_pdl_per_s);
-static_assert(1q_ft_pdl_per_s * 10q_s == 10q_ft_pdl);
-static_assert(10q_ft_pdl / 1q_ft_pdl_per_s == 10q_s);
+static_assert(10_q_ft_pdl / 10_q_s == 1_q_ft_pdl_per_s);
+static_assert(1_q_ft_pdl_per_s * 10_q_s == 10_q_ft_pdl);
+static_assert(10_q_ft_pdl / 1_q_ft_pdl_per_s == 10_q_s);
 
 // static_assert(detail::unit_text<dim_power, foot_pound_force_per_second>() == "ft_lbf/s");
 
diff --git a/test/unit_test/static/math_test.cpp b/test/unit_test/static/math_test.cpp
index e32967de..64322d94 100644
--- a/test/unit_test/static/math_test.cpp
+++ b/test/unit_test/static/math_test.cpp
@@ -31,14 +31,14 @@ namespace {
   using namespace units::physical::si::literals;
   using namespace units::physical::international::literals;
 
-  static_assert(is_same_v<decltype(pow<0>(2q_m)), std::int64_t>);
-  static_assert(is_same_v<decltype(pow<1>(2q_m)), decltype(2q_m)>);
-  static_assert(is_same_v<decltype(pow<2>(2q_m)), decltype(4q_m2)>);
-  static_assert(is_same_v<decltype(pow<2>(2q_km)), decltype(4q_km2)>);
-  static_assert(is_same_v<decltype(pow<2>(2q_ft)), decltype(4q_ft2)>);
-  static_assert(is_same_v<decltype(sqrt(4q_m2)), decltype(2q_m)>);
-  static_assert(is_same_v<decltype(sqrt(4q_km2)), decltype(2q_km)>);
-  static_assert(is_same_v<decltype(sqrt(4q_ft2)), decltype(2q_ft)>);
+  static_assert(is_same_v<decltype(pow<0>(2_q_m)), std::int64_t>);
+  static_assert(is_same_v<decltype(pow<1>(2_q_m)), decltype(2_q_m)>);
+  static_assert(is_same_v<decltype(pow<2>(2_q_m)), decltype(4_q_m2)>);
+  static_assert(is_same_v<decltype(pow<2>(2_q_km)), decltype(4_q_km2)>);
+  static_assert(is_same_v<decltype(pow<2>(2_q_ft)), decltype(4_q_ft2)>);
+  static_assert(is_same_v<decltype(sqrt(4_q_m2)), decltype(2_q_m)>);
+  static_assert(is_same_v<decltype(sqrt(4_q_km2)), decltype(2_q_km)>);
+  static_assert(is_same_v<decltype(sqrt(4_q_ft2)), decltype(2_q_ft)>);
 
 
 }  // namespace
diff --git a/test/unit_test/static/quantity_point_test.cpp b/test/unit_test/static/quantity_point_test.cpp
index b440a6cc..e3d501ed 100644
--- a/test/unit_test/static/quantity_point_test.cpp
+++ b/test/unit_test/static/quantity_point_test.cpp
@@ -58,23 +58,23 @@ static_assert(is_same_v<quantity_point<dim_length, kilometre, int>::unit, kilome
 
 // constructors
 
-static_assert(quantity_point<dim_length, metre, int>().relative() == 0q_m);
-constexpr quantity_point<dim_length, metre, int> km{1000q_m};
-static_assert(km.relative() == 1000q_m);
+static_assert(quantity_point<dim_length, metre, int>().relative() == 0_q_m);
+constexpr quantity_point<dim_length, metre, int> km{1000_q_m};
+static_assert(km.relative() == 1000_q_m);
 static_assert(quantity_point<dim_length, metre, int>(km).relative() == km.relative());
 
-static_assert(quantity_point<dim_length, metre, int>(1q_m).relative() == 1q_m);
+static_assert(quantity_point<dim_length, metre, int>(1_q_m).relative() == 1_q_m);
 static_assert(!std::is_constructible_v<quantity_point<dim_length, metre, int>, double>); // truncating conversion
-static_assert(quantity_point<dim_length, metre, double>(1.0q_m).relative() == 1.0q_m);
-static_assert(quantity_point<dim_length, metre, double>(1q_m).relative() == 1q_m);
-static_assert(quantity_point<dim_length, metre, long double>(3.14q_m).relative() == 3.14q_m);
+static_assert(quantity_point<dim_length, metre, double>(1.0_q_m).relative() == 1.0_q_m);
+static_assert(quantity_point<dim_length, metre, double>(1_q_m).relative() == 1_q_m);
+static_assert(quantity_point<dim_length, metre, long double>(3.14_q_m).relative() == 3.14_q_m);
 
-static_assert(quantity_point<dim_length, metre, int>(km).relative() == 1000q_m);
+static_assert(quantity_point<dim_length, metre, int>(km).relative() == 1000_q_m);
 static_assert(!std::is_constructible_v<quantity_point<dim_length, metre, int>,
                                        quantity_point<dim_length, metre, double>>);  // truncating conversion
-static_assert(quantity_point<dim_length, metre, double>(quantity_point(1000.0q_m)).relative() == 1000.0q_m);
-static_assert(quantity_point<dim_length, metre, double>(km).relative() == 1000.0q_m);
-static_assert(quantity_point<dim_length, metre, int>(quantity_point(1q_km)).relative() == 1000q_m);
+static_assert(quantity_point<dim_length, metre, double>(quantity_point(1000.0_q_m)).relative() == 1000.0_q_m);
+static_assert(quantity_point<dim_length, metre, double>(km).relative() == 1000.0_q_m);
+static_assert(quantity_point<dim_length, metre, int>(quantity_point(1_q_km)).relative() == 1000_q_m);
 static_assert(!std::is_constructible_v<quantity_point<dim_length, metre, int>,
                                        quantity_point<dim_time, second, int>>);  // different dimensions
 static_assert(!std::is_constructible_v<quantity_point<dim_length, kilometre, int>,
@@ -82,7 +82,7 @@ static_assert(!std::is_constructible_v<quantity_point<dim_length, kilometre, int
 
 // assignment operator
 
-static_assert([]() { quantity_point<dim_length, metre, int> l1(1q_m), l2{}; return l2 = l1; }().relative() == 1q_m);
+static_assert([]() { quantity_point<dim_length, metre, int> l1(1_q_m), l2{}; return l2 = l1; }().relative() == 1_q_m);
 
 // static member functions
 
@@ -98,24 +98,24 @@ static_assert(quantity_point<dim_length, metre, double>::max().relative().count(
 static_assert([](auto v) {
   auto vv = v++;
   return std::pair(v, vv);
-}(km) == std::pair(quantity_point<dim_length, metre, int>(1001q_m), quantity_point<dim_length, metre, int>(1000q_m)));
+}(km) == std::pair(quantity_point<dim_length, metre, int>(1001_q_m), quantity_point<dim_length, metre, int>(1000_q_m)));
 static_assert([](auto v) {
   auto vv = ++v;
   return std::pair(v, vv);
-}(km) == std::pair(quantity_point<dim_length, metre, int>(1001q_m), quantity_point<dim_length, metre, int>(1001q_m)));
+}(km) == std::pair(quantity_point<dim_length, metre, int>(1001_q_m), quantity_point<dim_length, metre, int>(1001_q_m)));
 static_assert([](auto v) {
   auto vv = v--;
   return std::pair(v, vv);
-}(km) == std::pair(quantity_point<dim_length, metre, int>(999q_m), quantity_point<dim_length, metre, int>(1000q_m)));
+}(km) == std::pair(quantity_point<dim_length, metre, int>(999_q_m), quantity_point<dim_length, metre, int>(1000_q_m)));
 static_assert([](auto v) {
   auto vv = --v;
   return std::pair(v, vv);
-}(km) == std::pair(quantity_point<dim_length, metre, int>(999q_m), quantity_point<dim_length, metre, int>(999q_m)));
+}(km) == std::pair(quantity_point<dim_length, metre, int>(999_q_m), quantity_point<dim_length, metre, int>(999_q_m)));
 
 // compound assignment
 
-static_assert((quantity_point(1q_m) += 1q_m).relative().count() == 2);
-static_assert((quantity_point(2q_m) -= 1q_m).relative().count() == 1);
+static_assert((quantity_point(1_q_m) += 1_q_m).relative().count() == 2);
+static_assert((quantity_point(2_q_m) -= 1_q_m).relative().count() == 1);
 
 // non-member arithmetic operators
 
@@ -138,48 +138,48 @@ static_assert(
     is_same_v<decltype(quantity_point<dim_length, kilometre, double>() - quantity_point<dim_length, metre, int>()),
                    length<metre, double>>);
 
-static_assert((1q_m + km).relative().count() == 1001);
-static_assert((quantity_point(1q_m) + 1q_km).relative().count() == 1001);
-static_assert((km - 1q_m).relative().count() == 999);
-static_assert((quantity_point(1q_km) - quantity_point(1q_m)).count() == 999);
+static_assert((1_q_m + km).relative().count() == 1001);
+static_assert((quantity_point(1_q_m) + 1_q_km).relative().count() == 1001);
+static_assert((km - 1_q_m).relative().count() == 999);
+static_assert((quantity_point(1_q_km) - quantity_point(1_q_m)).count() == 999);
 
 // comparators
 
-static_assert(quantity_point(2q_m) + 1q_m == quantity_point(3q_m));
-static_assert(!(2q_m + quantity_point(2q_m) == quantity_point(3q_m)));
-static_assert(quantity_point(2q_m) + 2q_m != quantity_point(3q_m));
-static_assert(!(2q_m + quantity_point(2q_m) != quantity_point(4q_m)));
-static_assert(quantity_point(2q_m) > quantity_point(1q_m));
-static_assert(!(quantity_point(1q_m) > quantity_point(1q_m)));
-static_assert(quantity_point(1q_m) < quantity_point(2q_m));
-static_assert(!(quantity_point(2q_m) < quantity_point(2q_m)));
-static_assert(quantity_point(2q_m) >= quantity_point(1q_m));
-static_assert(quantity_point(2q_m) >= quantity_point(2q_m));
-static_assert(!(quantity_point(2q_m) >= quantity_point(3q_m)));
-static_assert(quantity_point(1q_m) <= quantity_point(2q_m));
-static_assert(quantity_point(2q_m) <= quantity_point(2q_m));
-static_assert(!(quantity_point(3q_m) <= quantity_point(2q_m)));
+static_assert(quantity_point(2_q_m) + 1_q_m == quantity_point(3_q_m));
+static_assert(!(2_q_m + quantity_point(2_q_m) == quantity_point(3_q_m)));
+static_assert(quantity_point(2_q_m) + 2_q_m != quantity_point(3_q_m));
+static_assert(!(2_q_m + quantity_point(2_q_m) != quantity_point(4_q_m)));
+static_assert(quantity_point(2_q_m) > quantity_point(1_q_m));
+static_assert(!(quantity_point(1_q_m) > quantity_point(1_q_m)));
+static_assert(quantity_point(1_q_m) < quantity_point(2_q_m));
+static_assert(!(quantity_point(2_q_m) < quantity_point(2_q_m)));
+static_assert(quantity_point(2_q_m) >= quantity_point(1_q_m));
+static_assert(quantity_point(2_q_m) >= quantity_point(2_q_m));
+static_assert(!(quantity_point(2_q_m) >= quantity_point(3_q_m)));
+static_assert(quantity_point(1_q_m) <= quantity_point(2_q_m));
+static_assert(quantity_point(2_q_m) <= quantity_point(2_q_m));
+static_assert(!(quantity_point(3_q_m) <= quantity_point(2_q_m)));
 
-static_assert(quantity_point(3q_m) == quantity_point(3.0q_m));
-static_assert(quantity_point(3q_m) != quantity_point(3.14q_m));
-static_assert(quantity_point(2q_m) > quantity_point(1.0q_m));
-static_assert(quantity_point(1.0q_m) < quantity_point(2q_m));
-static_assert(quantity_point(2.0q_m) >= quantity_point(1q_m));
-static_assert(quantity_point(1q_m) <= quantity_point(2.0q_m));
+static_assert(quantity_point(3_q_m) == quantity_point(3.0_q_m));
+static_assert(quantity_point(3_q_m) != quantity_point(3.14_q_m));
+static_assert(quantity_point(2_q_m) > quantity_point(1.0_q_m));
+static_assert(quantity_point(1.0_q_m) < quantity_point(2_q_m));
+static_assert(quantity_point(2.0_q_m) >= quantity_point(1_q_m));
+static_assert(quantity_point(1_q_m) <= quantity_point(2.0_q_m));
 
-static_assert(quantity_point(1000q_m) == quantity_point(1q_km));
-static_assert(quantity_point(1001q_m) != quantity_point(1q_km));
-static_assert(quantity_point(1001q_m) > quantity_point(1q_km));
-static_assert(quantity_point(999q_m) < quantity_point(1q_km));
-static_assert(quantity_point(1000q_m) >= quantity_point(1q_km));
-static_assert(quantity_point(1000q_m) <= quantity_point(1q_km));
+static_assert(quantity_point(1000_q_m) == quantity_point(1_q_km));
+static_assert(quantity_point(1001_q_m) != quantity_point(1_q_km));
+static_assert(quantity_point(1001_q_m) > quantity_point(1_q_km));
+static_assert(quantity_point(999_q_m) < quantity_point(1_q_km));
+static_assert(quantity_point(1000_q_m) >= quantity_point(1_q_km));
+static_assert(quantity_point(1000_q_m) <= quantity_point(1_q_km));
 
 // alias units
 
-static_assert(quantity_point(2q_l) + 2q_ml == quantity_point(2002q_ml));
-static_assert(2q_l + quantity_point(2q_ml) == quantity_point(2002q_cm3));
-static_assert(quantity_point(2q_l) + 2q_cm3 == quantity_point(2002q_ml));
-static_assert(2q_dm3 + quantity_point(2q_cm3) == quantity_point(2002q_ml));
+static_assert(quantity_point(2_q_l) + 2_q_ml == quantity_point(2002_q_ml));
+static_assert(2_q_l + quantity_point(2_q_ml) == quantity_point(2002_q_cm3));
+static_assert(quantity_point(2_q_l) + 2_q_cm3 == quantity_point(2002_q_ml));
+static_assert(2_q_dm3 + quantity_point(2_q_cm3) == quantity_point(2002_q_ml));
 
 // is_quantity_point
 
@@ -201,47 +201,47 @@ static_assert(is_same_v<common_quantity_point<quantity_point<dim_length, kilomet
 
 using namespace units::physical::us::literals;
 
-static_assert(std::equality_comparable<decltype(quantity_point(1q_m))>);
-static_assert(std::equality_comparable_with<decltype(quantity_point(1q_m)), decltype(quantity_point(1q_km))>);
-static_assert(quantity_point(0q_m) == quantity_point(0q_ft_us));
-static_assert(std::equality_comparable_with<decltype(quantity_point(1q_m)), decltype(quantity_point(1q_ft_us))>);
+static_assert(std::equality_comparable<decltype(quantity_point(1_q_m))>);
+static_assert(std::equality_comparable_with<decltype(quantity_point(1_q_m)), decltype(quantity_point(1_q_km))>);
+static_assert(quantity_point(0_q_m) == quantity_point(0_q_ft_us));
+static_assert(std::equality_comparable_with<decltype(quantity_point(1_q_m)), decltype(quantity_point(1_q_ft_us))>);
 
 // quantity_cast
 
 static_assert(
-    is_same_v<decltype(quantity_point_cast<scaled_unit<ratio(1), metre>>(quantity_point(2q_km)))::unit, metre>);
+    is_same_v<decltype(quantity_point_cast<scaled_unit<ratio(1), metre>>(quantity_point(2_q_km)))::unit, metre>);
 
-static_assert(quantity_point_cast<quantity_point<dim_length, metre, int>>(quantity_point(2q_km)).relative().count() ==
+static_assert(quantity_point_cast<quantity_point<dim_length, metre, int>>(quantity_point(2_q_km)).relative().count() ==
               2000);
 static_assert(
-    quantity_point_cast<quantity_point<dim_length, kilometre, int>>(quantity_point(2000q_m)).relative().count() == 2);
-static_assert(quantity_point_cast<quantity_point<dim_length, metre, int>>(quantity_point(1.23q_m)).relative().count() ==
+    quantity_point_cast<quantity_point<dim_length, kilometre, int>>(quantity_point(2000_q_m)).relative().count() == 2);
+static_assert(quantity_point_cast<quantity_point<dim_length, metre, int>>(quantity_point(1.23_q_m)).relative().count() ==
               1);
-static_assert(quantity_point_cast<length<metre, int>>(quantity_point(2q_km)).relative().count() == 2000);
-static_assert(quantity_point_cast<length<kilometre, int>>(quantity_point(2000q_m)).relative().count() == 2);
-static_assert(quantity_point_cast<length<metre, int>>(quantity_point(1.23q_m)).relative().count() == 1);
-static_assert(quantity_point_cast<metre>(quantity_point(2q_km)).relative().count() == 2000);
-static_assert(quantity_point_cast<kilometre>(quantity_point(2000q_m)).relative().count() == 2);
-static_assert(quantity_point_cast<int>(quantity_point(1.23q_m)).relative().count() == 1);
+static_assert(quantity_point_cast<length<metre, int>>(quantity_point(2_q_km)).relative().count() == 2000);
+static_assert(quantity_point_cast<length<kilometre, int>>(quantity_point(2000_q_m)).relative().count() == 2);
+static_assert(quantity_point_cast<length<metre, int>>(quantity_point(1.23_q_m)).relative().count() == 1);
+static_assert(quantity_point_cast<metre>(quantity_point(2_q_km)).relative().count() == 2000);
+static_assert(quantity_point_cast<kilometre>(quantity_point(2000_q_m)).relative().count() == 2);
+static_assert(quantity_point_cast<int>(quantity_point(1.23_q_m)).relative().count() == 1);
 
 // time
 
-static_assert(quantity_point{1q_h} == quantity_point{3600q_s});
+static_assert(quantity_point{1_q_h} == quantity_point{3600_q_s});
 
 template<typename Metre>
 concept no_crossdimensional_equality = !requires
 {
-    quantity_point(1q_s) == quantity_point(length<Metre, int>(1));
+    quantity_point(1_q_s) == quantity_point(length<Metre, int>(1));
 };
 
 static_assert(no_crossdimensional_equality<metre>);
 
 // length
 
-static_assert(quantity_point(1q_km) != quantity_point(1q_m));
-static_assert(quantity_point(1q_km) == quantity_point(1000q_m));
-static_assert(quantity_point(1q_km) + 1q_m == quantity_point(1001q_m));
-static_assert(1q_km + quantity_point(1q_m) == quantity_point(1001q_m));
+static_assert(quantity_point(1_q_km) != quantity_point(1_q_m));
+static_assert(quantity_point(1_q_km) == quantity_point(1000_q_m));
+static_assert(quantity_point(1_q_km) + 1_q_m == quantity_point(1001_q_m));
+static_assert(1_q_km + quantity_point(1_q_m) == quantity_point(1001_q_m));
 
 template<class T>
 concept dimensional_analysis = requires(T t)
diff --git a/test/unit_test/static/quantity_test.cpp b/test/unit_test/static/quantity_test.cpp
index fa26699f..882cc91e 100644
--- a/test/unit_test/static/quantity_test.cpp
+++ b/test/unit_test/static/quantity_test.cpp
@@ -69,9 +69,9 @@ static_assert(length<metre, double>(3.14).count() == 3.14);
 static_assert(length<metre, int>(km).count() == 1000);
 static_assert(!std::is_constructible_v<length<metre, int>,
                                        length<metre, double>>);  // truncating conversion
-static_assert(length<metre, double>(1000.0q_m).count() == 1000.0);
+static_assert(length<metre, double>(1000.0_q_m).count() == 1000.0);
 static_assert(length<metre, double>(km).count() == 1000.0);
-static_assert(length<metre, int>(1q_km).count() == 1000);
+static_assert(length<metre, int>(1_q_km).count() == 1000);
 static_assert(!std::is_constructible_v<length<metre, int>,
                                        physical::si::time<second, int>>);  // different dimensions
 static_assert(!std::is_constructible_v<length<kilometre, int>,
@@ -116,18 +116,18 @@ static_assert([](auto v) {
 
 // compound assignment
 
-static_assert((1q_m += 1q_m).count() == 2);
-static_assert((2q_m -= 1q_m).count() == 1);
-static_assert((1q_m *= 2).count() == 2);
-static_assert((2q_m /= 2).count() == 1);
-static_assert((7q_m %= 2).count() == 1);
-static_assert((7q_m %= 2q_m).count() == 1);
+static_assert((1_q_m += 1_q_m).count() == 2);
+static_assert((2_q_m -= 1_q_m).count() == 1);
+static_assert((1_q_m *= 2).count() == 2);
+static_assert((2_q_m /= 2).count() == 1);
+static_assert((7_q_m %= 2).count() == 1);
+static_assert((7_q_m %= 2_q_m).count() == 1);
 
-static_assert((2.5q_m += 3q_m).count() == 5.5);
-static_assert((2.5q_m += 3.5q_m).count() == 6);
+static_assert((2.5_q_m += 3_q_m).count() == 5.5);
+static_assert((2.5_q_m += 3.5_q_m).count() == 6);
 
-static_assert((2.5q_m *= 3).count() == 7.5);
-static_assert((2.5q_m *= 3.5).count() == 8.75);
+static_assert((2.5_q_m *= 3).count() == 7.5);
+static_assert((2.5_q_m *= 3.5).count() == 8.75);
 
 // operations not allowed for the respective quantities
 template<typename Metre>
@@ -136,11 +136,11 @@ concept invalid_compound_assignments = requires()
     !requires(length<Metre, double> l) { l %= 2.; };
     !requires(length<Metre, double> l) { l %= 2; };
     !requires(length<Metre, int> l) { l %= 2.; };
-    !requires(length<Metre, double> l) { l %= 2.q_m; };
-    !requires(length<Metre, double> l) { l %= 2q_m; };
-    !requires(length<Metre, int> l) { l %= 2.q_m; };
-    !requires(length<Metre, int> l) { l += 3.5q_m; };
-    !requires(length<Metre, int> l) { l *= 3.5q_m; };
+    !requires(length<Metre, double> l) { l %= 2._q_m; };
+    !requires(length<Metre, double> l) { l %= 2_q_m; };
+    !requires(length<Metre, int> l) { l %= 2._q_m; };
+    !requires(length<Metre, int> l) { l += 3.5_q_m; };
+    !requires(length<Metre, int> l) { l *= 3.5_q_m; };
 };
 
 static_assert(invalid_compound_assignments<metre>);
@@ -179,22 +179,22 @@ static_assert(is_same_v<decltype(physical::si::time<minute>() / length<metre>())
 static_assert(is_same_v<decltype(length<metre, int>() % short(1)), length<metre, int>>);
 static_assert(is_same_v<decltype(length<metre, int>() % length<metre, short>(1)), length<metre, int>>);
 
-static_assert((1q_m + km).count() == 1001);
-static_assert((1q_m + 1q_km).count() == 1001);
-static_assert((km - 1q_m).count() == 999);
-static_assert((1q_km - 1q_m).count() == 999);
-static_assert((2q_m * 2).count() == 4);
-static_assert((3 * 3q_m).count() == 9);
-static_assert((4q_m / 2).count() == 2);
-static_assert((4q_km / 2q_m).count() == 2);
-static_assert((4000q_m / 2q_m).count() == 2000);
-static_assert((7q_m % 2).count() == 1);
-static_assert((7q_m % 2q_m).count() == 1);
-static_assert((7q_km % 2000q_m).count() == 1000);
+static_assert((1_q_m + km).count() == 1001);
+static_assert((1_q_m + 1_q_km).count() == 1001);
+static_assert((km - 1_q_m).count() == 999);
+static_assert((1_q_km - 1_q_m).count() == 999);
+static_assert((2_q_m * 2).count() == 4);
+static_assert((3 * 3_q_m).count() == 9);
+static_assert((4_q_m / 2).count() == 2);
+static_assert((4_q_km / 2_q_m).count() == 2);
+static_assert((4000_q_m / 2_q_m).count() == 2000);
+static_assert((7_q_m % 2).count() == 1);
+static_assert((7_q_m % 2_q_m).count() == 1);
+static_assert((7_q_km % 2000_q_m).count() == 1000);
 
-static_assert((10q_km2 * 10q_km2) / 50q_km2 == 2q_km2);
+static_assert((10_q_km2 * 10_q_km2) / 50_q_km2 == 2_q_km2);
 
-constexpr auto q1 = 10q_km / 5q_m;
+constexpr auto q1 = 10_q_km / 5_q_m;
 static_assert(std::is_same_v<decltype(q1), const dimensionless<scaled_unit<ratio(1, 1, 3), one>, std::int64_t>>);
 static_assert(q1.count() == 2);
 
@@ -203,47 +203,47 @@ static_assert(q2.count() == 2000);
 
 static_assert(quantity_cast<one>(q1).count() == 2000);
 
-constexpr auto q3 = 10q_s * 2q_kHz;
+constexpr auto q3 = 10_q_s * 2_q_kHz;
 static_assert(std::is_same_v<decltype(q3), const dimensionless<scaled_unit<ratio(1, 1, 3), one>, std::int64_t>>);
 static_assert(q3.count() == 20);
 
 // comparators
 
-static_assert(2q_m + 1q_m == 3q_m);
-static_assert(!(2q_m + 2q_m == 3q_m));
-static_assert(2q_m + 2q_m != 3q_m);
-static_assert(!(2q_m + 2q_m != 4q_m));
-static_assert(2q_m > 1q_m);
-static_assert(!(1q_m > 1q_m));
-static_assert(1q_m < 2q_m);
-static_assert(!(2q_m < 2q_m));
-static_assert(2q_m >= 1q_m);
-static_assert(2q_m >= 2q_m);
-static_assert(!(2q_m >= 3q_m));
-static_assert(1q_m <= 2q_m);
-static_assert(2q_m <= 2q_m);
-static_assert(!(3q_m <= 2q_m));
+static_assert(2_q_m + 1_q_m == 3_q_m);
+static_assert(!(2_q_m + 2_q_m == 3_q_m));
+static_assert(2_q_m + 2_q_m != 3_q_m);
+static_assert(!(2_q_m + 2_q_m != 4_q_m));
+static_assert(2_q_m > 1_q_m);
+static_assert(!(1_q_m > 1_q_m));
+static_assert(1_q_m < 2_q_m);
+static_assert(!(2_q_m < 2_q_m));
+static_assert(2_q_m >= 1_q_m);
+static_assert(2_q_m >= 2_q_m);
+static_assert(!(2_q_m >= 3_q_m));
+static_assert(1_q_m <= 2_q_m);
+static_assert(2_q_m <= 2_q_m);
+static_assert(!(3_q_m <= 2_q_m));
 
-static_assert(3q_m == 3.0q_m);
-static_assert(3q_m != 3.14q_m);
-static_assert(2q_m > 1.0q_m);
-static_assert(1.0q_m < 2q_m);
-static_assert(2.0q_m >= 1q_m);
-static_assert(1q_m <= 2.0q_m);
+static_assert(3_q_m == 3.0_q_m);
+static_assert(3_q_m != 3.14_q_m);
+static_assert(2_q_m > 1.0_q_m);
+static_assert(1.0_q_m < 2_q_m);
+static_assert(2.0_q_m >= 1_q_m);
+static_assert(1_q_m <= 2.0_q_m);
 
-static_assert(1000q_m == 1q_km);
-static_assert(1001q_m != 1q_km);
-static_assert(1001q_m > 1q_km);
-static_assert(999q_m < 1q_km);
-static_assert(1000q_m >= 1q_km);
-static_assert(1000q_m <= 1q_km);
+static_assert(1000_q_m == 1_q_km);
+static_assert(1001_q_m != 1_q_km);
+static_assert(1001_q_m > 1_q_km);
+static_assert(999_q_m < 1_q_km);
+static_assert(1000_q_m >= 1_q_km);
+static_assert(1000_q_m <= 1_q_km);
 
 // alias units
 
-static_assert(2q_l + 2q_ml == 2002q_ml);
-static_assert(2q_l + 2q_ml == 2002q_cm3);
-static_assert(2q_l + 2q_cm3 == 2002q_ml);
-static_assert(2q_dm3 + 2q_cm3 == 2002q_ml);
+static_assert(2_q_l + 2_q_ml == 2002_q_ml);
+static_assert(2_q_l + 2_q_ml == 2002_q_cm3);
+static_assert(2_q_l + 2_q_cm3 == 2002_q_ml);
+static_assert(2_q_dm3 + 2_q_cm3 == 2002_q_ml);
 
 // is_quantity
 
@@ -261,10 +261,10 @@ static_assert(is_same_v<common_quantity<length<kilometre, long long>, length<mil
 
 using namespace units::physical::us::literals;
 
-static_assert(std::equality_comparable<decltype(1q_m)>);
-static_assert(std::equality_comparable_with<decltype(1q_m), decltype(1q_cm)>);
-static_assert(0q_m == 0q_ft_us);
-static_assert(std::equality_comparable_with<decltype(1q_m), decltype(1q_ft_us)>);
+static_assert(std::equality_comparable<decltype(1_q_m)>);
+static_assert(std::equality_comparable_with<decltype(1_q_m), decltype(1_q_cm)>);
+static_assert(0_q_m == 0_q_ft_us);
+static_assert(std::equality_comparable_with<decltype(1_q_m), decltype(1_q_ft_us)>);
 static_assert(std::equality_comparable_with<dimensionless<one>, int>);
 static_assert(std::equality_comparable_with<dimensionless<one>, double>);
 static_assert(std::equality_comparable_with<dimensionless<one, int>, int>);
@@ -272,14 +272,14 @@ static_assert(!std::equality_comparable_with<dimensionless<one, int>, double>);
 
 // quantity_cast
 
-static_assert(is_same_v<decltype(quantity_cast<scaled_unit<ratio(1), metre>>(2q_km))::unit, metre>);
+static_assert(is_same_v<decltype(quantity_cast<scaled_unit<ratio(1), metre>>(2_q_km))::unit, metre>);
 
-static_assert(quantity_cast<length<metre, int>>(2q_km).count() == 2000);
-static_assert(quantity_cast<length<kilometre, int>>(2000q_m).count() == 2);
-static_assert(quantity_cast<length<metre, int>>(1.23q_m).count() == 1);
-static_assert(quantity_cast<metre>(2q_km).count() == 2000);
-static_assert(quantity_cast<kilometre>(2000q_m).count() == 2);
-static_assert(quantity_cast<int>(1.23q_m).count() == 1);
+static_assert(quantity_cast<length<metre, int>>(2_q_km).count() == 2000);
+static_assert(quantity_cast<length<kilometre, int>>(2000_q_m).count() == 2);
+static_assert(quantity_cast<length<metre, int>>(1.23_q_m).count() == 1);
+static_assert(quantity_cast<metre>(2_q_km).count() == 2000);
+static_assert(quantity_cast<kilometre>(2000_q_m).count() == 2);
+static_assert(quantity_cast<int>(1.23_q_m).count() == 1);
 
 // dimensionless
 
@@ -308,37 +308,37 @@ concept invalid_dimensionless_operations = requires
 };
 static_assert(invalid_dimensionless_operations<int>);
 
-static_assert(std::is_same_v<decltype(10q_km / 5q_km), quantity<dim_one, one, std::int64_t>>);
+static_assert(std::is_same_v<decltype(10_q_km / 5_q_km), quantity<dim_one, one, std::int64_t>>);
 
-static_assert(quantity_cast<percent>(50.q_m / 100.q_m).count() == 50);
-static_assert(50.q_m / 100.q_m == dimensionless<percent>(50));
+static_assert(quantity_cast<percent>(50._q_m / 100._q_m).count() == 50);
+static_assert(50._q_m / 100._q_m == dimensionless<percent>(50));
 
 static_assert(dimensionless<one>(dimensionless<percent>(50)).count() == 0.5);
 
 // time
 
-static_assert(1q_h == 3600q_s);
+static_assert(1_q_h == 3600_q_s);
 
 template<typename Metre>
-concept no_crossdimensional_equality = !requires { 1q_s == length<Metre, int>(1); };
+concept no_crossdimensional_equality = !requires { 1_q_s == length<Metre, int>(1); };
 
 static_assert(no_crossdimensional_equality<metre>);
 
 // length
 
-static_assert(1q_km == 1000q_m);
-static_assert(1q_km + 1q_m == 1001q_m);
-static_assert(10q_km / 5q_km == 2);
-static_assert(10q_km / 2 == 5q_km);
+static_assert(1_q_km == 1000_q_m);
+static_assert(1_q_km + 1_q_m == 1001_q_m);
+static_assert(10_q_km / 5_q_km == 2);
+static_assert(10_q_km / 2 == 5_q_km);
 
 // speed
 
-static_assert(10q_m / 5q_s == 2q_m_per_s);
-static_assert(10 / 5q_s * 1q_m == 2q_m_per_s);
-static_assert(1q_km / 1q_s == 1000q_m_per_s);
-static_assert(2q_km_per_h * 2q_h == 4q_km);
-static_assert(2q_km / 2q_km_per_h == 1q_h);
+static_assert(10_q_m / 5_q_s == 2_q_m_per_s);
+static_assert(10 / 5_q_s * 1_q_m == 2_q_m_per_s);
+static_assert(1_q_km / 1_q_s == 1000_q_m_per_s);
+static_assert(2_q_km_per_h * 2_q_h == 4_q_km);
+static_assert(2_q_km / 2_q_km_per_h == 1_q_h);
 
-static_assert(is_same_v<decltype(pow<2>(2q_m)), decltype(4q_m2)>);
+static_assert(is_same_v<decltype(pow<2>(2_q_m)), decltype(4_q_m2)>);
 
 }  // namespace
diff --git a/test/unit_test/static/si_cgs_test.cpp b/test/unit_test/static/si_cgs_test.cpp
index f828a691..73a1069e 100644
--- a/test/unit_test/static/si_cgs_test.cpp
+++ b/test/unit_test/static/si_cgs_test.cpp
@@ -61,15 +61,15 @@ namespace si_test {
 
 using namespace units::physical::si::literals;
 
-static_assert(cgs::length<cgs::centimetre>(100) == 1q_m);
-static_assert(cgs::mass<cgs::gram>(1'000) == 1q_kg);
-static_assert(cgs::time<cgs::second>(1) == 1q_s);
-static_assert(cgs::speed<cgs::centimetre_per_second>(100) == 1q_m_per_s);
-static_assert(cgs::acceleration<cgs::gal>(100) == 1q_m_per_s2);
-static_assert(cgs::force<cgs::dyne>(100'000) == 1q_N);
-static_assert(cgs::energy<cgs::erg>(10'000'000) == 1q_J);
-static_assert(cgs::power<cgs::erg_per_second>(10'000'000) == 1q_W);
-static_assert(cgs::pressure<cgs::barye>(10) == 1q_Pa);
+static_assert(cgs::length<cgs::centimetre>(100) == 1_q_m);
+static_assert(cgs::mass<cgs::gram>(1'000) == 1_q_kg);
+static_assert(cgs::time<cgs::second>(1) == 1_q_s);
+static_assert(cgs::speed<cgs::centimetre_per_second>(100) == 1_q_m_per_s);
+static_assert(cgs::acceleration<cgs::gal>(100) == 1_q_m_per_s2);
+static_assert(cgs::force<cgs::dyne>(100'000) == 1_q_N);
+static_assert(cgs::energy<cgs::erg>(10'000'000) == 1_q_J);
+static_assert(cgs::power<cgs::erg_per_second>(10'000'000) == 1_q_W);
+static_assert(cgs::pressure<cgs::barye>(10) == 1_q_Pa);
 
 }
 
@@ -77,15 +77,15 @@ namespace cgs_test {
 
 using namespace units::physical::cgs::literals;
 
-static_assert(100q_cm == si::length<si::metre>(1));
-static_assert(1'000q_g == si::mass<si::kilogram>(1));
-static_assert(1q_s == si::time<si::second>(1));
-static_assert(100q_cm_per_s == si::speed<si::metre_per_second>(1));
-static_assert(100q_Gal == si::acceleration<si::metre_per_second_sq>(1));
-static_assert(100'000q_dyn == si::force<si::newton>(1));
-static_assert(10'000'000q_erg == si::energy<si::joule>(1));
-static_assert(10'000'000q_erg_per_s == si::power<si::watt>(1));
-static_assert(10q_Ba == si::pressure<si::pascal>(1));
+static_assert(100_q_cm == si::length<si::metre>(1));
+static_assert(1'000_q_g == si::mass<si::kilogram>(1));
+static_assert(1_q_s == si::time<si::second>(1));
+static_assert(100_q_cm_per_s == si::speed<si::metre_per_second>(1));
+static_assert(100_q_Gal == si::acceleration<si::metre_per_second_sq>(1));
+static_assert(100'000_q_dyn == si::force<si::newton>(1));
+static_assert(10'000'000_q_erg == si::energy<si::joule>(1));
+static_assert(10'000'000_q_erg_per_s == si::power<si::watt>(1));
+static_assert(10_q_Ba == si::pressure<si::pascal>(1));
 
 }
 
@@ -94,15 +94,15 @@ namespace both_test {
 using namespace units::physical::si::literals;
 using namespace units::physical::cgs::literals;
 
-// static_assert(100q_cm == 1q_m);   // ambiguous
-// static_assert(1'000q_g == 1q_kg); // ambiguous
-static_assert(1q_s == 1q_s);
-static_assert(100q_cm_per_s == 1q_m_per_s);
-static_assert(100q_Gal == 1q_m_per_s2);
-static_assert(100'000q_dyn == 1q_N);
-static_assert(10'000'000q_erg == 1q_J);
-static_assert(10'000'000q_erg_per_s == 1q_W);
-static_assert(10q_Ba == quantity_cast<double>(1q_Pa));
+// static_assert(100_q_cm == 1_q_m);   // ambiguous
+// static_assert(1'000_q_g == 1_q_kg); // ambiguous
+static_assert(1_q_s == 1_q_s);
+static_assert(100_q_cm_per_s == 1_q_m_per_s);
+static_assert(100_q_Gal == 1_q_m_per_s2);
+static_assert(100'000_q_dyn == 1_q_N);
+static_assert(10'000'000_q_erg == 1_q_J);
+static_assert(10'000'000_q_erg_per_s == 1_q_W);
+static_assert(10_q_Ba == quantity_cast<double>(1_q_Pa));
 
 }
 
@@ -110,41 +110,41 @@ namespace cgs_test {
 
 // addition
 
-// static_assert(100q_cm + si::length<si::metre>(1) == si::length<si::metre>(2)); // should not compile (different dimensions)
-// static_assert(si::length<si::metre>(1) + 100q_cm == si::length<si::metre>(2)); // should not compile (different dimensions)
-static_assert(quantity_cast<si::length<si::metre>>(100q_cm) + si::length<si::metre>(1) == si::length<si::metre>(2));
-static_assert(si::length<si::metre>(1) + quantity_cast<si::length<si::metre>>(100q_cm) == si::length<si::metre>(2));
-static_assert(100q_cm + quantity_cast<cgs::length<cgs::centimetre>>(si::length<si::metre>(1)) == 200q_cm);
-static_assert(quantity_cast<cgs::length<cgs::centimetre>>(si::length<si::metre>(1)) + 100q_cm == 200q_cm);
+// static_assert(100_q_cm + si::length<si::metre>(1) == si::length<si::metre>(2)); // should not compile (different dimensions)
+// static_assert(si::length<si::metre>(1) + 100_q_cm == si::length<si::metre>(2)); // should not compile (different dimensions)
+static_assert(quantity_cast<si::length<si::metre>>(100_q_cm) + si::length<si::metre>(1) == si::length<si::metre>(2));
+static_assert(si::length<si::metre>(1) + quantity_cast<si::length<si::metre>>(100_q_cm) == si::length<si::metre>(2));
+static_assert(100_q_cm + quantity_cast<cgs::length<cgs::centimetre>>(si::length<si::metre>(1)) == 200_q_cm);
+static_assert(quantity_cast<cgs::length<cgs::centimetre>>(si::length<si::metre>(1)) + 100_q_cm == 200_q_cm);
 
 // substraction
 
-// static_assert(500q_cm - si::length<si::metre>(1) == si::length<si::metre>(4)); // should not compile (different dimensions)
-// static_assert(si::length<si::metre>(5) - 100q_cm == si::length<si::metre>(4)); // should not compile (different dimensions)
-static_assert(quantity_cast<si::length<si::metre>>(500q_cm) - si::length<si::metre>(1) == si::length<si::metre>(4));
-static_assert(si::length<si::metre>(5) - quantity_cast<si::length<si::metre>>(100q_cm) == si::length<si::metre>(4));
-static_assert(500q_cm - quantity_cast<cgs::length<cgs::centimetre>>(si::length<si::metre>(1)) == 400q_cm);
-static_assert(quantity_cast<cgs::length<cgs::centimetre>>(si::length<si::metre>(5)) - 100q_cm == 400q_cm);
+// static_assert(500_q_cm - si::length<si::metre>(1) == si::length<si::metre>(4)); // should not compile (different dimensions)
+// static_assert(si::length<si::metre>(5) - 100_q_cm == si::length<si::metre>(4)); // should not compile (different dimensions)
+static_assert(quantity_cast<si::length<si::metre>>(500_q_cm) - si::length<si::metre>(1) == si::length<si::metre>(4));
+static_assert(si::length<si::metre>(5) - quantity_cast<si::length<si::metre>>(100_q_cm) == si::length<si::metre>(4));
+static_assert(500_q_cm - quantity_cast<cgs::length<cgs::centimetre>>(si::length<si::metre>(1)) == 400_q_cm);
+static_assert(quantity_cast<cgs::length<cgs::centimetre>>(si::length<si::metre>(5)) - 100_q_cm == 400_q_cm);
 
 // multiplication
 
-// static_assert(200q_cm * si::length<si::metre>(2) == si::area<si::square_metre>(4)); // should not compile (unknown dimension)
+// static_assert(200_q_cm * si::length<si::metre>(2) == si::area<si::square_metre>(4)); // should not compile (unknown dimension)
 
-static_assert(quantity_cast<si::dim_length>(200.q_cm) * si::length<si::metre>(2) == si::area<si::square_metre>(4));
-static_assert(200.q_cm * quantity_cast<cgs::dim_length>(si::length<si::metre>(2)) == 40'000q_cm2);
+static_assert(quantity_cast<si::dim_length>(200._q_cm) * si::length<si::metre>(2) == si::area<si::square_metre>(4));
+static_assert(200._q_cm * quantity_cast<cgs::dim_length>(si::length<si::metre>(2)) == 40'000_q_cm2);
 
 // TODO Add support for quantity_cast on an unknown_dimension?
-// static_assert(quantity_cast<si::area<si::square_metre>>(200q_cm * si::length<si::metre>(2)) == si::area<si::square_metre>(4));
-// static_assert(quantity_cast<si::dim_area>(200q_cm * si::length<si::metre>(2)) == si::area<si::square_metre>(4));
-// static_assert(quantity_cast<cgs::area<cgs::square_centimeters>>(200q_cm * si::length<si::metre>(2)) == 40'000q_sq_cm);
-// static_assert(quantity_cast<cgs::dim_area>(200q_cm * si::length<si::metre>(2)) == 40'000q_sq_cm);
+// static_assert(quantity_cast<si::area<si::square_metre>>(200_q_cm * si::length<si::metre>(2)) == si::area<si::square_metre>(4));
+// static_assert(quantity_cast<si::dim_area>(200_q_cm * si::length<si::metre>(2)) == si::area<si::square_metre>(4));
+// static_assert(quantity_cast<cgs::area<cgs::square_centimeters>>(200_q_cm * si::length<si::metre>(2)) == 40'000_q_sq_cm);
+// static_assert(quantity_cast<cgs::dim_area>(200_q_cm * si::length<si::metre>(2)) == 40'000_q_sq_cm);
 
 // division
 
-// static_assert(si::area<si::square_metre>(4) / 200q_cm == si::length<si::metre>(2)); // should not compile (unknown dimension)
+// static_assert(si::area<si::square_metre>(4) / 200_q_cm == si::length<si::metre>(2)); // should not compile (unknown dimension)
 
-static_assert(si::area<si::square_metre>(4) / quantity_cast<si::length<si::metre>>(200q_cm) == si::length<si::metre>(2));
-static_assert(quantity_cast<cgs::area<cgs::square_centimetre>>(si::area<si::square_metre>(4)) / 200.q_cm == 200q_cm);
+static_assert(si::area<si::square_metre>(4) / quantity_cast<si::length<si::metre>>(200_q_cm) == si::length<si::metre>(2));
+static_assert(quantity_cast<cgs::area<cgs::square_centimetre>>(si::area<si::square_metre>(4)) / 200._q_cm == 200_q_cm);
 
 }
 
diff --git a/test/unit_test/static/si_fps_test.cpp b/test/unit_test/static/si_fps_test.cpp
index e058b593..20062022 100644
--- a/test/unit_test/static/si_fps_test.cpp
+++ b/test/unit_test/static/si_fps_test.cpp
@@ -65,40 +65,40 @@ namespace si_literals {
 
 using namespace units::physical::si::literals;
 
-static_assert(fps::length<fps::foot>(1) == 0.3048q_m);
-static_assert(fps::mass<fps::pound>(1) == 0.45359237q_kg);
-static_assert(fps::time<fps::second>(1) == 1q_s);
-static_assert(fps::speed<fps::foot_per_second>(1) == 0.3048q_m_per_s);
-static_assert(fps::area<fps::square_foot>(1) == 0.09290304q_m2);
-static_assert(fps::acceleration<fps::foot_per_second_sq>(1) == 0.3048q_m_per_s2);
-static_assert(fps::force<fps::poundal>(1) > 0.138254q_N && 
-              fps::force<fps::poundal>(1) < 0.138256q_N);
-static_assert(fps::energy<fps::foot_poundal>(1) > 0.042140110093804q_J && 
-              fps::energy<fps::foot_poundal>(1) < 0.042140110093806q_J);
-static_assert(fps::power<fps::foot_poundal_per_second>(1) > 0.042140110093804q_W && 
-              fps::power<fps::foot_poundal_per_second>(1) < 0.042140110093806q_W);
-static_assert(fps::pressure<fps::poundal_per_foot_sq>(1) >  1.4881639435q_Pa &&
-              fps::pressure<fps::poundal_per_foot_sq>(1) <  1.4881639437q_Pa);
+static_assert(fps::length<fps::foot>(1) == 0.3048_q_m);
+static_assert(fps::mass<fps::pound>(1) == 0.45359237_q_kg);
+static_assert(fps::time<fps::second>(1) == 1_q_s);
+static_assert(fps::speed<fps::foot_per_second>(1) == 0.3048_q_m_per_s);
+static_assert(fps::area<fps::square_foot>(1) == 0.09290304_q_m2);
+static_assert(fps::acceleration<fps::foot_per_second_sq>(1) == 0.3048_q_m_per_s2);
+static_assert(fps::force<fps::poundal>(1) > 0.138254_q_N && 
+              fps::force<fps::poundal>(1) < 0.138256_q_N);
+static_assert(fps::energy<fps::foot_poundal>(1) > 0.042140110093804_q_J && 
+              fps::energy<fps::foot_poundal>(1) < 0.042140110093806_q_J);
+static_assert(fps::power<fps::foot_poundal_per_second>(1) > 0.042140110093804_q_W && 
+              fps::power<fps::foot_poundal_per_second>(1) < 0.042140110093806_q_W);
+static_assert(fps::pressure<fps::poundal_per_foot_sq>(1) >  1.4881639435_q_Pa &&
+              fps::pressure<fps::poundal_per_foot_sq>(1) <  1.4881639437_q_Pa);
 }
 
 namespace fps_literals {
 
 using namespace units::physical::fps::literals;
 
-static_assert(1q_ft == si::length<si::metre>(0.3048));
-static_assert(1q_lb == si::mass<si::kilogram>(0.45359237));
-static_assert(1q_s == si::time<si::second>(1));
-static_assert(1q_ft_per_s == si::speed<si::metre_per_second>(0.3048));
-static_assert(1q_ft2 == si::area<si::square_metre>(0.09290304));
-static_assert(1q_ft_per_s2 == si::acceleration<si::metre_per_second_sq>(0.3048));
-static_assert(1q_pdl > si::force<si::newton>(0.138254) && 
-              1q_pdl < si::force<si::newton>(0.138256));
-static_assert(1q_ft_pdl > si::energy<si::joule>(0.042140110093804) && 
-              1q_ft_pdl < si::energy<si::joule>(0.042140110093806));
-static_assert(1q_ft_pdl_per_s > si::power<si::watt>(0.042140110093804) && 
-              1q_ft_pdl_per_s < si::power<si::watt>(0.042140110093806));
-static_assert(1q_pdl_per_ft2> si::pressure<si::pascal>(1.4881639435) &&
-              1q_pdl_per_ft2 < si::pressure<si::pascal>(1.4881639437));
+static_assert(1_q_ft == si::length<si::metre>(0.3048));
+static_assert(1_q_lb == si::mass<si::kilogram>(0.45359237));
+static_assert(1_q_s == si::time<si::second>(1));
+static_assert(1_q_ft_per_s == si::speed<si::metre_per_second>(0.3048));
+static_assert(1_q_ft2 == si::area<si::square_metre>(0.09290304));
+static_assert(1_q_ft_per_s2 == si::acceleration<si::metre_per_second_sq>(0.3048));
+static_assert(1_q_pdl > si::force<si::newton>(0.138254) && 
+              1_q_pdl < si::force<si::newton>(0.138256));
+static_assert(1_q_ft_pdl > si::energy<si::joule>(0.042140110093804) && 
+              1_q_ft_pdl < si::energy<si::joule>(0.042140110093806));
+static_assert(1_q_ft_pdl_per_s > si::power<si::watt>(0.042140110093804) && 
+              1_q_ft_pdl_per_s < si::power<si::watt>(0.042140110093806));
+static_assert(1_q_pdl_per_ft2> si::pressure<si::pascal>(1.4881639435) &&
+              1_q_pdl_per_ft2 < si::pressure<si::pascal>(1.4881639437));
 }
 
 namespace fps_plus_si_literals {
@@ -106,22 +106,22 @@ namespace fps_plus_si_literals {
 using namespace units::physical::si::literals;
 using namespace units::physical::fps::literals;
 
-// static_assert(100q_cm == 1q_m);   // ambiguous
-// static_assert(1'000q_g == 1q_kg); // ambiguous
-static_assert(1q_ft == 0.3048q_m);
-static_assert(1q_lb == 0.45359237q_kg);
-static_assert(1q_s  == 1q_s);
-static_assert(1q_ft_per_s == 0.3048q_m_per_s);
-static_assert(1q_ft2 == 0.09290304q_m2);
-static_assert(1q_ft_per_s2 == 0.3048q_m_per_s2);
-static_assert(1q_pdl > 0.138254q_N && 
-              1q_pdl < 0.138256q_N);
-static_assert(1q_ft_pdl > 0.042140110093804q_J && 
-              1q_ft_pdl < 0.042140110093806q_J);
-static_assert(1q_ft_pdl_per_s > 0.042140110093804q_W && 
-              1q_ft_pdl_per_s < 0.042140110093806q_W);
-static_assert(1q_pdl_per_ft2> 1.4881639435q_Pa &&
-              1q_pdl_per_ft2 <1.4881639437q_Pa);
+// static_assert(100_q_cm == 1_q_m);   // ambiguous
+// static_assert(1'000_q_g == 1_q_kg); // ambiguous
+static_assert(1_q_ft == 0.3048_q_m);
+static_assert(1_q_lb == 0.45359237_q_kg);
+static_assert(1_q_s  == 1_q_s);
+static_assert(1_q_ft_per_s == 0.3048_q_m_per_s);
+static_assert(1_q_ft2 == 0.09290304_q_m2);
+static_assert(1_q_ft_per_s2 == 0.3048_q_m_per_s2);
+static_assert(1_q_pdl > 0.138254_q_N && 
+              1_q_pdl < 0.138256_q_N);
+static_assert(1_q_ft_pdl > 0.042140110093804_q_J && 
+              1_q_ft_pdl < 0.042140110093806_q_J);
+static_assert(1_q_ft_pdl_per_s > 0.042140110093804_q_W && 
+              1_q_ft_pdl_per_s < 0.042140110093806_q_W);
+static_assert(1_q_pdl_per_ft2> 1.4881639435_q_Pa &&
+              1_q_pdl_per_ft2 <1.4881639437_q_Pa);
 
 }
 
@@ -131,35 +131,35 @@ using namespace units::physical::fps::literals;
 
 // addition
 
-// static_assert(si::length<si::metre>(1) + 1q_ft == si::length<si::metre>(1.3048)); // should not compile (different dimensions)
-// static_assert(1q_ft / 0.3048 + si::length<si::metre>(1) == si::length<si::metre>(1.3048)); // should not compile (different dimensions)
-static_assert(quantity_cast<si::length<si::metre>>(1.q_ft / 0.3048) + si::length<si::metre>(1) == si::length<si::metre>(2));   // 1 m in ft + 1 m
-static_assert(si::length<si::metre>(1) + quantity_cast<si::length<si::metre>>(1.q_ft / 0.3048) == si::length<si::metre>(2));   // 1 m + 1 m in ft
-static_assert(1q_ft + quantity_cast<fps::length<fps::foot>>(si::length<si::metre>(0.3048)) == 2q_ft);                         // 1 ft + 1 ft in m
-static_assert(quantity_cast<fps::length<fps::foot>>(si::length<si::metre>(0.3048)) + 1q_ft == 2q_ft);                         // 1 ft in m + 1 ft
+// static_assert(si::length<si::metre>(1) + 1_q_ft == si::length<si::metre>(1.3048)); // should not compile (different dimensions)
+// static_assert(1_q_ft / 0.3048 + si::length<si::metre>(1) == si::length<si::metre>(1.3048)); // should not compile (different dimensions)
+static_assert(quantity_cast<si::length<si::metre>>(1._q_ft / 0.3048) + si::length<si::metre>(1) == si::length<si::metre>(2));   // 1 m in ft + 1 m
+static_assert(si::length<si::metre>(1) + quantity_cast<si::length<si::metre>>(1._q_ft / 0.3048) == si::length<si::metre>(2));   // 1 m + 1 m in ft
+static_assert(1_q_ft + quantity_cast<fps::length<fps::foot>>(si::length<si::metre>(0.3048)) == 2_q_ft);                         // 1 ft + 1 ft in m
+static_assert(quantity_cast<fps::length<fps::foot>>(si::length<si::metre>(0.3048)) + 1_q_ft == 2_q_ft);                         // 1 ft in m + 1 ft
 
 // substraction
 
-// static_assert(1q_ft - si::length<si::metre>(1) == -si::length<si::metre>(0.6952)); // should not compile (different dimensions)
-// static_assert(si::length<si::metre>(1) - 1q_ft == si::length<si::metre>(0.6952)); // should not compile (different dimensions)
-static_assert(quantity_cast<si::length<si::metre>>(6.q_ft) - si::length<si::metre>(1) > si::length<si::metre>(0.8287) &&
-              quantity_cast<si::length<si::metre>>(6.q_ft) - si::length<si::metre>(1) < si::length<si::metre>(0.8289));      // 6 ft in m - 1 m  = ... m
-static_assert(si::length<si::metre>(5) - quantity_cast<si::length<si::metre>>(6q_ft) == si::length<si::metre>(3.1712));       // 5 m - 6 ft in m  = ...
-static_assert(6.q_ft - quantity_cast<fps::length<fps::foot>>(si::length<si::metre>(0.3048)) == 5.q_ft);                       // 6 ft - 1 ft in m = 5 ft
-static_assert(quantity_cast<fps::length<fps::foot>>(si::length<si::metre>(1.8288)) - 1.q_ft == 5.q_ft);                       // 6 ft in m - 1 ft = 5 ft
+// static_assert(1_q_ft - si::length<si::metre>(1) == -si::length<si::metre>(0.6952)); // should not compile (different dimensions)
+// static_assert(si::length<si::metre>(1) - 1_q_ft == si::length<si::metre>(0.6952)); // should not compile (different dimensions)
+static_assert(quantity_cast<si::length<si::metre>>(6._q_ft) - si::length<si::metre>(1) > si::length<si::metre>(0.8287) &&
+              quantity_cast<si::length<si::metre>>(6._q_ft) - si::length<si::metre>(1) < si::length<si::metre>(0.8289));      // 6 ft in m - 1 m  = ... m
+static_assert(si::length<si::metre>(5) - quantity_cast<si::length<si::metre>>(6_q_ft) == si::length<si::metre>(3.1712));       // 5 m - 6 ft in m  = ...
+static_assert(6._q_ft - quantity_cast<fps::length<fps::foot>>(si::length<si::metre>(0.3048)) == 5._q_ft);                       // 6 ft - 1 ft in m = 5 ft
+static_assert(quantity_cast<fps::length<fps::foot>>(si::length<si::metre>(1.8288)) - 1._q_ft == 5._q_ft);                       // 6 ft in m - 1 ft = 5 ft
 
 // multiplication
 
-// static_assert(2q_ft * si::length<si::metre>(2) == si::area<si::square_metre>(1.2192)); // should not compile (unknown dimension)
-// static_assert(quantity_cast<si::length<si::metre>>(2.q_ft) * si::length<si::metre>(2) == si::area<si::square_metre>(1.2192)); 
-static_assert(quantity_cast<si::length<si::metre>>(2.q_ft) * si::length<si::metre>(0.6096) == si::area<si::square_metre>(0.371612160));  // 2 ft * 2 ft == 4 sq ft
-static_assert(2.q_ft * quantity_cast<fps::length<fps::foot>>(si::length<si::metre>(0.6096)) == 4.q_ft2);
+// static_assert(2_q_ft * si::length<si::metre>(2) == si::area<si::square_metre>(1.2192)); // should not compile (unknown dimension)
+// static_assert(quantity_cast<si::length<si::metre>>(2._q_ft) * si::length<si::metre>(2) == si::area<si::square_metre>(1.2192)); 
+static_assert(quantity_cast<si::length<si::metre>>(2._q_ft) * si::length<si::metre>(0.6096) == si::area<si::square_metre>(0.371612160));  // 2 ft * 2 ft == 4 sq ft
+static_assert(2._q_ft * quantity_cast<fps::length<fps::foot>>(si::length<si::metre>(0.6096)) == 4._q_ft2);
 
 // division
 
-// static_assert(si::area<si::square_metre>(4) / 200q_cm == si::length<si::metre>(2)); // should not compile (unknown dimension)
-static_assert(si::area<si::square_metre>(1.48644864) / quantity_cast<si::length<si::metre>>(4q_ft) == si::length<si::metre>(1.2192)); // 16 ft2 / 4 ft = 4 ft
-static_assert(quantity_cast<fps::area<fps::square_foot>>(si::area<si::square_metre>(1.48644864)) / 4.q_ft == 4.q_ft);                 // 16 ft2 / 4 ft = 4 ft
+// static_assert(si::area<si::square_metre>(4) / 200_q_cm == si::length<si::metre>(2)); // should not compile (unknown dimension)
+static_assert(si::area<si::square_metre>(1.48644864) / quantity_cast<si::length<si::metre>>(4_q_ft) == si::length<si::metre>(1.2192)); // 16 ft2 / 4 ft = 4 ft
+static_assert(quantity_cast<fps::area<fps::square_foot>>(si::area<si::square_metre>(1.48644864)) / 4._q_ft == 4._q_ft);                 // 16 ft2 / 4 ft = 4 ft
 
 }
 
diff --git a/test/unit_test/static/si_test.cpp b/test/unit_test/static/si_test.cpp
index 6c12779a..be55ece9 100644
--- a/test/unit_test/static/si_test.cpp
+++ b/test/unit_test/static/si_test.cpp
@@ -32,18 +32,18 @@ using namespace units::physical::si;
 
 // length
 
-static_assert(1q_km == 1000q_m);
-static_assert(1q_m == 100q_cm);
-static_assert(1q_m == 10q_dm);
-static_assert(1q_m == 1000q_mm);
-static_assert(1q_hm == 100q_m);
-static_assert(1q_au == 149'597'870'700q_m);
-static_assert(1q_km + 1q_m == 1001q_m);
-static_assert(10q_km / 5q_km == 2);
-static_assert(10q_km / 5q_km < 3);
-static_assert(100q_mm / 5q_cm == dimensionless<scaled_unit<ratio(1, 1, -1), one>>(20));
-static_assert(100q_mm / 5q_cm == dimensionless<one>(2));
-static_assert(10q_km / 2 == 5q_km);
+static_assert(1_q_km == 1000_q_m);
+static_assert(1_q_m == 100_q_cm);
+static_assert(1_q_m == 10_q_dm);
+static_assert(1_q_m == 1000_q_mm);
+static_assert(1_q_hm == 100_q_m);
+static_assert(1_q_au == 149'597'870'700_q_m);
+static_assert(1_q_km + 1_q_m == 1001_q_m);
+static_assert(10_q_km / 5_q_km == 2);
+static_assert(10_q_km / 5_q_km < 3);
+static_assert(100_q_mm / 5_q_cm == dimensionless<scaled_unit<ratio(1, 1, -1), one>>(20));
+static_assert(100_q_mm / 5_q_cm == dimensionless<one>(2));
+static_assert(10_q_km / 2 == 5_q_km);
 
 static_assert(millimetre::symbol == "mm");
 static_assert(centimetre::symbol == "cm");
@@ -52,9 +52,9 @@ static_assert(kilometre::symbol == "km");
 
 // mass
 
-static_assert(1q_kg == 1000q_g);
-static_assert(1q_t == 1000q_kg);
-static_assert(1q_kt == 1000000q_kg);
+static_assert(1_q_kg == 1000_q_g);
+static_assert(1_q_t == 1000_q_kg);
+static_assert(1_q_kt == 1000000_q_kg);
 
 static_assert(kilogram::symbol == "kg");
 static_assert(tonne::symbol == "t");
@@ -62,14 +62,14 @@ static_assert(kilotonne::symbol == "kt");
 
 // time
 
-static_assert(1q_us == 1000q_ns);
-static_assert(1q_ms == 1000q_us);
-static_assert(1q_s == 1000q_ms);
-static_assert(1q_min == 60q_s);
-static_assert(1q_h == 60q_min);
-static_assert(1q_h == 3600q_s);
-static_assert(1q_d == 24q_h);
-static_assert(1q_d == 86'400q_s);
+static_assert(1_q_us == 1000_q_ns);
+static_assert(1_q_ms == 1000_q_us);
+static_assert(1_q_s == 1000_q_ms);
+static_assert(1_q_min == 60_q_s);
+static_assert(1_q_h == 60_q_min);
+static_assert(1_q_h == 3600_q_s);
+static_assert(1_q_d == 24_q_h);
+static_assert(1_q_d == 86'400_q_s);
 
 static_assert(nanosecond::symbol == "ns");
 static_assert(microsecond::symbol == basic_symbol_text("µs", "us"));
@@ -87,11 +87,11 @@ static_assert(millisecond::symbol == "ms");
 
 // frequency
 
-static_assert(1000q_mHz == 1q_Hz);
-static_assert(1000q_Hz == 1q_kHz);
-static_assert(1000q_kHz == 1q_MHz);
-static_assert(1000q_MHz == 1q_GHz);
-static_assert(1000q_GHz == 1q_THz);
+static_assert(1000_q_mHz == 1_q_Hz);
+static_assert(1000_q_Hz == 1_q_kHz);
+static_assert(1000_q_kHz == 1_q_MHz);
+static_assert(1000_q_MHz == 1_q_GHz);
+static_assert(1000_q_GHz == 1_q_THz);
 
 static_assert(millihertz::symbol == "mHz");
 static_assert(kilohertz::symbol == "kHz");
@@ -99,89 +99,89 @@ static_assert(megahertz::symbol == "MHz");
 static_assert(gigahertz::symbol == "GHz");
 static_assert(terahertz::symbol == "THz");
 
-static_assert(2 / 1q_s == 2q_Hz);
-static_assert(120 / 1q_min == 2q_Hz);
-static_assert(1000 / 1q_s == 1q_kHz);
-static_assert(1 / 1q_ms == 1q_kHz);
-static_assert(3.2q_GHz == 3'200'000'000q_Hz);
-static_assert((10q_Hz * 1q_min).count() == 10);
-static_assert(10q_Hz * 1q_min == dimensionless<scaled_unit<ratio(60), one>>(10));
-static_assert(10q_Hz * 1q_min == dimensionless<one>(600));
-static_assert(2 / 1q_Hz == 2q_s);
+static_assert(2 / 1_q_s == 2_q_Hz);
+static_assert(120 / 1_q_min == 2_q_Hz);
+static_assert(1000 / 1_q_s == 1_q_kHz);
+static_assert(1 / 1_q_ms == 1_q_kHz);
+static_assert(3.2_q_GHz == 3'200'000'000_q_Hz);
+static_assert((10_q_Hz * 1_q_min).count() == 10);
+static_assert(10_q_Hz * 1_q_min == dimensionless<scaled_unit<ratio(60), one>>(10));
+static_assert(10_q_Hz * 1_q_min == dimensionless<one>(600));
+static_assert(2 / 1_q_Hz == 2_q_s);
 
 // force
-static_assert(10q_kg * 10q_m_per_s2 == 100q_N);
-static_assert(100q_N / 1q_m_per_s2 == 100q_kg);
-static_assert(100q_N / 1q_kg == 100q_m_per_s2);
+static_assert(10_q_kg * 10_q_m_per_s2 == 100_q_N);
+static_assert(100_q_N / 1_q_m_per_s2 == 100_q_kg);
+static_assert(100_q_N / 1_q_kg == 100_q_m_per_s2);
 
 // pressure
 
-static_assert(10q_N / 10q_m2 == 1q_Pa);
-static_assert(10q_N / 1q_Pa == 10q_m2);
-static_assert(1q_Pa * 10q_m2 == 10q_N);
+static_assert(10_q_N / 10_q_m2 == 1_q_Pa);
+static_assert(10_q_N / 1_q_Pa == 10_q_m2);
+static_assert(1_q_Pa * 10_q_m2 == 10_q_N);
 
 // energy
 
-static_assert(1000q_mJ == 1q_J);
-static_assert(1000q_J == 1q_kJ);
-static_assert(1000q_kJ == 1q_MJ);
-static_assert(1000q_MJ == 1q_GJ);
+static_assert(1000_q_mJ == 1_q_J);
+static_assert(1000_q_J == 1_q_kJ);
+static_assert(1000_q_kJ == 1_q_MJ);
+static_assert(1000_q_MJ == 1_q_GJ);
 
 static_assert(millijoule::symbol == "mJ");
 static_assert(kilojoule::symbol == "kJ");
 static_assert(megajoule::symbol == "MJ");
 static_assert(gigajoule::symbol == "GJ");
 
-static_assert(10q_N * 10q_m == 100q_J);
-static_assert(100q_J / 10q_m == 10q_N);
-static_assert(100q_J / 10q_N == 10q_m);
-static_assert(10q_Pa * 10q_m3 == 100q_J);
-static_assert(100q_J / 10q_Pa == 10q_m3);
-static_assert(100q_J / 10q_m3 == 10q_Pa);
+static_assert(10_q_N * 10_q_m == 100_q_J);
+static_assert(100_q_J / 10_q_m == 10_q_N);
+static_assert(100_q_J / 10_q_N == 10_q_m);
+static_assert(10_q_Pa * 10_q_m3 == 100_q_J);
+static_assert(100_q_J / 10_q_Pa == 10_q_m3);
+static_assert(100_q_J / 10_q_m3 == 10_q_Pa);
 
 // power
 
-static_assert(1000q_mW == 1q_W);
-static_assert(1000q_W == 1q_kW);
-static_assert(1000q_kW == 1q_MW);
-static_assert(1000q_MW == 1q_GW);
+static_assert(1000_q_mW == 1_q_W);
+static_assert(1000_q_W == 1_q_kW);
+static_assert(1000_q_kW == 1_q_MW);
+static_assert(1000_q_MW == 1_q_GW);
 
 static_assert(milliwatt::symbol == "mW");
 static_assert(kilowatt::symbol == "kW");
 static_assert(megawatt::symbol == "MW");
 static_assert(gigawatt::symbol == "GW");
 
-static_assert(10q_J / 10q_s == 1q_W);
-static_assert(1q_W * 10q_s == 10q_J);
-static_assert(10q_J / 1q_W == 10q_s);
+static_assert(10_q_J / 10_q_s == 1_q_W);
+static_assert(1_q_W * 10_q_s == 10_q_J);
+static_assert(10_q_J / 1_q_W == 10_q_s);
 
 // electric charge
 
-static_assert(10q_A * 10q_s == 100q_C);
-static_assert(100q_C / 10q_A == 10q_s);
-static_assert(100q_C / 10q_s == 10q_A);
+static_assert(10_q_A * 10_q_s == 100_q_C);
+static_assert(100_q_C / 10_q_A == 10_q_s);
+static_assert(100_q_C / 10_q_s == 10_q_A);
 
 // voltage
 
-static_assert(10q_W / 10q_A == 1q_V);
-static_assert(10q_W / 1q_V == 10q_A);
-static_assert(1q_V * 10q_A == 10q_W);
-static_assert(10q_J / 10q_C == 1q_V);
-static_assert(10q_J / 1q_V == 10q_C);
-static_assert(10q_C * 1q_V == 10q_J);
+static_assert(10_q_W / 10_q_A == 1_q_V);
+static_assert(10_q_W / 1_q_V == 10_q_A);
+static_assert(1_q_V * 10_q_A == 10_q_W);
+static_assert(10_q_J / 10_q_C == 1_q_V);
+static_assert(10_q_J / 1_q_V == 10_q_C);
+static_assert(10_q_C * 1_q_V == 10_q_J);
 
 // capacitance
 
-static_assert(10q_C / 10q_V == 1q_F);
-static_assert(10q_C / 1q_F == 10q_V);
-static_assert(10q_V * 1q_F == 10q_C);
+static_assert(10_q_C / 10_q_V == 1_q_F);
+static_assert(10_q_C / 1_q_F == 10_q_V);
+static_assert(10_q_V * 1_q_F == 10_q_C);
 
 // magnetic induction
 
-static_assert(1q_T == 1q_V * 1q_s / (1q_m * 1q_m));
-static_assert(10q_T / 1q_s == 10q_V / (1q_m * 1q_m));
-static_assert(10q_T * (1q_m * 1q_m) == 10q_s * 1q_V);
-static_assert(10q_N / (1q_A * 1q_m) == 10q_T);
+static_assert(1_q_T == 1_q_V * 1_q_s / (1_q_m * 1_q_m));
+static_assert(10_q_T / 1_q_s == 10_q_V / (1_q_m * 1_q_m));
+static_assert(10_q_T * (1_q_m * 1_q_m) == 10_q_s * 1_q_V);
+static_assert(10_q_N / (1_q_A * 1_q_m) == 10_q_T);
 
 static_assert(millitesla::symbol == "mT");
 static_assert(microtesla::symbol == basic_symbol_text("µT", "uT"));
@@ -190,9 +190,9 @@ static_assert(picotesla::symbol == "pT");
 
 // magnetic flux
 
-static_assert(1q_Wb == 1q_T * 1q_m2);
-static_assert(1q_J == 1q_Wb * 1q_A);
-static_assert(1q_N * 1q_s == 1q_Wb * 1q_C / 1q_m);
+static_assert(1_q_Wb == 1_q_T * 1_q_m2);
+static_assert(1_q_J == 1_q_Wb * 1_q_A);
+static_assert(1_q_N * 1_q_s == 1_q_Wb * 1_q_C / 1_q_m);
 
 static_assert(milliweber::symbol == "mWb");
 static_assert(microweber::symbol == basic_symbol_text("µWb", "uWb"));
@@ -201,9 +201,9 @@ static_assert(picoweber::symbol == "pWb");
 
 // inductance
 
-static_assert(1q_H == 1q_Wb / 1q_A);
-static_assert(1q_V == 1q_H * 1q_A / 1q_s);
-static_assert(1q_J == 1q_H * 1q_A * 1q_A);
+static_assert(1_q_H == 1_q_Wb / 1_q_A);
+static_assert(1_q_V == 1_q_H * 1_q_A / 1_q_s);
+static_assert(1_q_J == 1_q_H * 1_q_A * 1_q_A);
 
 static_assert(millihenry::symbol == "mH");
 static_assert(microhenry::symbol == basic_symbol_text("µH", "uH"));
@@ -212,9 +212,9 @@ static_assert(picohenry::symbol == "pH");
 
 // conductance
 
-static_assert(1q_S * 1q_R == 1);
-static_assert(1q_S == 1q_A / 1q_V);
-static_assert(1q_W == 1q_A * 1q_A / 1q_S);
+static_assert(1_q_S * 1_q_R == 1);
+static_assert(1_q_S == 1_q_A / 1_q_V);
+static_assert(1_q_W == 1_q_A * 1_q_A / 1_q_S);
 
 static_assert(millisiemens::symbol == "mS");
 static_assert(microsiemens::symbol == basic_symbol_text("µS", "uS"));
@@ -222,16 +222,16 @@ static_assert(nanosiemens::symbol == "nS");
 
 // catalytic activity
 
-static_assert(1q_kat == 1q_mol / 1q_s);
-static_assert(1'000'000q_U == 1q_mol / 1q_min);
+static_assert(1_q_kat == 1_q_mol / 1_q_s);
+static_assert(1'000'000_q_U == 1_q_mol / 1_q_min);
 
 static_assert(katal::symbol == "kat");
 static_assert(enzyme_unit::symbol == "U");
 
 // absorbed dose
 
-static_assert(1q_Gy == 1q_J / 1q_kg);
-static_assert(9.q_W * 3q_s / 60q_kg == 450q_mGy);
+static_assert(1_q_Gy == 1_q_J / 1_q_kg);
+static_assert(9._q_W * 3_q_s / 60_q_kg == 450_q_mGy);
 
 static_assert(gray::symbol == "Gy");
 static_assert(milligray::symbol == "mGy");
@@ -241,42 +241,42 @@ static_assert(kilogray::symbol == "kGy");
 
 // speed
 
-static_assert(is_same_v<decltype(1q_km / 1q_s), speed<scaled_unit<ratio(1, 1, 3), metre_per_second>, std::int64_t>>);
+static_assert(is_same_v<decltype(1_q_km / 1_q_s), speed<scaled_unit<ratio(1, 1, 3), metre_per_second>, std::int64_t>>);
 
-static_assert(10q_m / 5q_s == 2q_m_per_s);
-static_assert(10 / 5q_s * 1q_m == 2q_m_per_s);
-static_assert(1q_km / 1q_s == 1000q_m_per_s);
-// static_assert(1q_km / 1q_h == 1q_km_per_h);  // should not compile
-static_assert(1.0q_km / 1q_h == 1q_km_per_h);
-static_assert(1000.0q_m / 3600.0q_s == 1q_km_per_h);
+static_assert(10_q_m / 5_q_s == 2_q_m_per_s);
+static_assert(10 / 5_q_s * 1_q_m == 2_q_m_per_s);
+static_assert(1_q_km / 1_q_s == 1000_q_m_per_s);
+// static_assert(1_q_km / 1_q_h == 1_q_km_per_h);  // should not compile
+static_assert(1.0_q_km / 1_q_h == 1_q_km_per_h);
+static_assert(1000.0_q_m / 3600.0_q_s == 1_q_km_per_h);
 
-static_assert(2q_km_per_h * 2q_h == 4q_km);
-// static_assert(2q_km_per_h * 15q_min == 500q_m); // should not compile
-static_assert(2q_km_per_h * 15.0q_min == 500q_m);
-static_assert(2.0q_km_per_h * 15q_min == 500q_m);
+static_assert(2_q_km_per_h * 2_q_h == 4_q_km);
+// static_assert(2_q_km_per_h * 15_q_min == 500_q_m); // should not compile
+static_assert(2_q_km_per_h * 15.0_q_min == 500_q_m);
+static_assert(2.0_q_km_per_h * 15_q_min == 500_q_m);
 
-static_assert(2q_km / 2q_km_per_h == 1q_h);
-// static_assert(2000q_m / 2q_km_per_h == 1q_h); // should not compile
-static_assert(quantity_cast<kilometre>(2000q_m) / 2q_km_per_h == 1q_h);
+static_assert(2_q_km / 2_q_km_per_h == 1_q_h);
+// static_assert(2000_q_m / 2_q_km_per_h == 1_q_h); // should not compile
+static_assert(quantity_cast<kilometre>(2000_q_m) / 2_q_km_per_h == 1_q_h);
 
 static_assert(detail::unit_text<dim_speed, metre_per_second>() == "m/s");
 static_assert(kilometre_per_hour::symbol == "km/h");
 
 // acceleration
 
-static_assert(10q_m_per_s / 10q_s == 1q_m_per_s2);
-static_assert(10q_m_per_s / 1q_m_per_s2 == 10q_s);
-static_assert(1q_m_per_s2 * 10q_s == 10q_m_per_s);
+static_assert(10_q_m_per_s / 10_q_s == 1_q_m_per_s2);
+static_assert(10_q_m_per_s / 1_q_m_per_s2 == 10_q_s);
+static_assert(1_q_m_per_s2 * 10_q_s == 10_q_m_per_s);
 
 static_assert(detail::unit_text<dim_acceleration, metre_per_second_sq>() == basic_symbol_text("m/s²", "m/s^2"));
 
 // area
 
-static_assert(10q_m * 10q_m == 100q_m2);
-static_assert(100q_m2 / 10q_m == 10q_m);
-static_assert(10q_km * 10q_km == 100q_km2);
-static_assert(1q_m2 == 10'000q_cm2);
-static_assert(1q_ha == 10'000q_m2);
+static_assert(10_q_m * 10_q_m == 100_q_m2);
+static_assert(100_q_m2 / 10_q_m == 10_q_m);
+static_assert(10_q_km * 10_q_km == 100_q_km2);
+static_assert(1_q_m2 == 10'000_q_cm2);
+static_assert(1_q_ha == 10'000_q_m2);
 
 static_assert(hectare::symbol == "ha");
 
@@ -284,13 +284,13 @@ static_assert(detail::unit_text<dim_area, square_metre>() == basic_symbol_text("
 
 // volume
 
-static_assert(1q_m * 1q_m * 1q_m == 1q_m3);
-static_assert(10q_m2 * 10q_m == 100q_m3);
-static_assert(10q_km * 10q_km * 10q_km == 1000q_km3);
-static_assert(1q_m3 == 1'000'000q_cm3);
-static_assert(1q_dm * 1q_dm * 1q_dm == 1q_l);
-static_assert(1000q_l == 1q_m3);
-static_assert(1q_kl == 1q_m3);
+static_assert(1_q_m * 1_q_m * 1_q_m == 1_q_m3);
+static_assert(10_q_m2 * 10_q_m == 100_q_m3);
+static_assert(10_q_km * 10_q_km * 10_q_km == 1000_q_km3);
+static_assert(1_q_m3 == 1'000'000_q_cm3);
+static_assert(1_q_dm * 1_q_dm * 1_q_dm == 1_q_l);
+static_assert(1000_q_l == 1_q_m3);
+static_assert(1_q_kl == 1_q_m3);
 
 static_assert(litre::symbol == "l");
 static_assert(kilolitre::symbol == "kl");
@@ -299,89 +299,89 @@ static_assert(detail::unit_text<dim_volume, cubic_metre>() == basic_symbol_text(
 
 /* ************** DERIVED DIMENSIONS IN TERMS OF OTHER UNITS **************** */
 
-static_assert(10q_N / 2q_m == 5q_N_per_m);
-static_assert(10q_N / 5q_N_per_m == 2q_m);
-static_assert(2q_m * 5q_N_per_m == 10q_N);
+static_assert(10_q_N / 2_q_m == 5_q_N_per_m);
+static_assert(10_q_N / 5_q_N_per_m == 2_q_m);
+static_assert(2_q_m * 5_q_N_per_m == 10_q_N);
 
 static_assert(detail::unit_text<dim_surface_tension, newton_per_metre>() == "N/m");
 
 // current density
 
-static_assert(12q_A_per_m2 == 60q_A / 5q_m2);
-static_assert(1q_A_per_m2 == 1q_S * 1q_V / 1q_m2);
+static_assert(12_q_A_per_m2 == 60_q_A / 5_q_m2);
+static_assert(1_q_A_per_m2 == 1_q_S * 1_q_V / 1_q_m2);
 
 static_assert(detail::unit_text<dim_current_density, ampere_per_metre_sq>() == basic_symbol_text("A/m²", "A/m^2"));
 
 // concentration
 
-static_assert(1q_mol_per_m3 == 1q_kg_per_m3 * 1q_mol / 1q_kg);
+static_assert(1_q_mol_per_m3 == 1_q_kg_per_m3 * 1_q_mol / 1_q_kg);
 static_assert(detail::unit_text<dim_concentration, ampere_per_metre_sq>() == basic_symbol_text("mol/m³", "mol/m^3"));
 
 // luminance
 
-static_assert(1q_cd_per_m2 == 1q_cd / 1q_m2);
+static_assert(1_q_cd_per_m2 == 1_q_cd / 1_q_m2);
 static_assert(detail::unit_text<dim_luminance, candela_per_metre_sq>() == basic_symbol_text("cd/m²", "cd/m^2"));
 
 // dynamic viscosity
 
-static_assert(1q_Pa_s == 1q_N * 1q_s / 1q_m2);
+static_assert(1_q_Pa_s == 1_q_N * 1_q_s / 1_q_m2);
 static_assert(detail::unit_text<dim_dynamic_viscosity, pascal_second>() == basic_symbol_text("Pa ⋅ s", "Pa s"));
 
 // [specific|molar] heath capacity
 
-static_assert(1q_J_per_K == 1q_J_per_kg_K * 1q_kg);
-static_assert(1q_J_per_K * 1q_K == 1q_s * 1q_N * 1q_m_per_s);
-static_assert(1q_J_per_mol_K == 1q_J_per_K / 1q_mol);
+static_assert(1_q_J_per_K == 1_q_J_per_kg_K * 1_q_kg);
+static_assert(1_q_J_per_K * 1_q_K == 1_q_s * 1_q_N * 1_q_m_per_s);
+static_assert(1_q_J_per_mol_K == 1_q_J_per_K / 1_q_mol);
 
 static_assert(detail::unit_text<dim_heat_capacity, joule_per_kelvin>() == "J/K");
 static_assert(detail::unit_text<dim_specific_heat_capacity, joule_per_kilogram_kelvin>() == basic_symbol_text("J ⋅ K⁻¹ ⋅ kg⁻¹", "J K^-1 kg^-1"));
 
 // thermal conductivity
 
-static_assert(20q_W_per_m_K * 10q_m * 300q_K == 60'000q_W);
+static_assert(20_q_W_per_m_K * 10_q_m * 300_q_K == 60'000_q_W);
 static_assert(detail::unit_text<dim_thermal_conductivity, watt_per_metre_kelvin>() == basic_symbol_text("W ⋅ m⁻¹ ⋅ K⁻¹", "W m^-1 K^-1"));
 
 // electric field strength
 
-static_assert(100q_N/20q_C == 5q_V_per_m);
-static_assert(1q_C * 10q_V_per_m * 3q_m == 30q_J);
+static_assert(100_q_N/20_q_C == 5_q_V_per_m);
+static_assert(1_q_C * 10_q_V_per_m * 3_q_m == 30_q_J);
 
 static_assert(detail::unit_text<dim_electric_field_strength, volt_per_metre>() == "V/m");
 
 // [surface] charge density
 
-static_assert(20.q_C / 40q_m3 == 0.5q_C_per_m3);
-static_assert(10.q_C / 20q_m2 == 0.5q_C_per_m2);
-static_assert(20.q_C_per_m3 == 10.q_C_per_m2 / 0.5q_m);
-static_assert(1q_C / 1q_m / 1q_m == 1q_C / 1q_m2);
-static_assert(1q_C_per_m2 == 1q_C_per_m3 * 1q_m);
-static_assert(1q_V_per_m * 10q_C_per_m3 * 1q_m3 == 10q_N);
+static_assert(20._q_C / 40_q_m3 == 0.5_q_C_per_m3);
+static_assert(10._q_C / 20_q_m2 == 0.5_q_C_per_m2);
+static_assert(20._q_C_per_m3 == 10._q_C_per_m2 / 0.5_q_m);
+static_assert(1_q_C / 1_q_m / 1_q_m == 1_q_C / 1_q_m2);
+static_assert(1_q_C_per_m2 == 1_q_C_per_m3 * 1_q_m);
+static_assert(1_q_V_per_m * 10_q_C_per_m3 * 1_q_m3 == 10_q_N);
 
 static_assert(detail::unit_text<dim_charge_density, coulomb_per_metre_cub>() == basic_symbol_text("C/m³", "C/m^3"));
 static_assert(detail::unit_text<dim_surface_charge_density, coulomb_per_metre_sq>() == basic_symbol_text("C/m²", "C/m^2"));
 
 // permittivity
 
-static_assert(1q_F_per_m == 1q_F / 1q_m);
-static_assert(1/(1q_F_per_m) * 1q_C * 1q_C / 1q_m2 == 1q_N);
-static_assert(1q_C_per_m3 / 1q_F_per_m * 1q_m == 1q_V_per_m);
+static_assert(1_q_F_per_m == 1_q_F / 1_q_m);
+static_assert(1/(1_q_F_per_m) * 1_q_C * 1_q_C / 1_q_m2 == 1_q_N);
+static_assert(1_q_C_per_m3 / 1_q_F_per_m * 1_q_m == 1_q_V_per_m);
 
 static_assert(detail::unit_text<dim_permittivity, farad_per_metre>() == "F/m");
 
 // permeability
 
-static_assert(1q_H_per_m * 1q_A / 1q_m == 1q_T);
-static_assert(1q_H_per_m * 1q_A * 1q_A == 1q_N);
+static_assert(1_q_H_per_m * 1_q_A / 1_q_m == 1_q_T);
+static_assert(1_q_H_per_m * 1_q_A * 1_q_A == 1_q_N);
 
 static_assert(detail::unit_text<dim_permeability, henry_per_metre>() == "H/m");
 
 // molar energy
 
-static_assert(1q_J_per_mol * 1q_mol_per_m3 * 1q_m3 == 1q_N * 1q_m);
+static_assert(1_q_J_per_mol * 1_q_mol_per_m3 * 1_q_m3 == 1_q_N * 1_q_m);
 
 static_assert(detail::unit_text<dim_molar_energy, joule_per_mole>() == "J/mol");
 
 // angular velocity
-static_assert(1q_rad / 1q_s == 1q_rad_per_s);
+static_assert(1_q_rad / 1_q_s == 1_q_rad_per_s);
 static_assert(detail::unit_text<dim_angular_velocity, radian_per_second>() == basic_symbol_text("ω", "w"));
 }  // namespace
diff --git a/test/unit_test/static/us_test.cpp b/test/unit_test/static/us_test.cpp
index 2256ceb4..ae086406 100644
--- a/test/unit_test/static/us_test.cpp
+++ b/test/unit_test/static/us_test.cpp
@@ -42,19 +42,19 @@ using namespace units::physical::international;
 
 // length
 
-static_assert(1q_yd == 0.9144q_m);
-static_assert(1q_yd == 3q_ft);
-static_assert(1q_ft == 12q_in);
-static_assert(1q_mi == 1760q_yd);
+static_assert(1_q_yd == 0.9144_q_m);
+static_assert(1_q_yd == 3_q_ft);
+static_assert(1_q_ft == 12_q_in);
+static_assert(1_q_mi == 1760_q_yd);
 
-static_assert(5q_in + 8q_cm == 207q_mm);
+static_assert(5_q_in + 8_q_cm == 207_q_mm);
 
 
 /* ************** DERIVED DIMENSIONS IN TERMS OF BASE UNITS **************** */
 
 // speed
 
-static_assert(10.0q_mi / 2q_h == 5q_mi_per_h);
+static_assert(10.0_q_mi / 2_q_h == 5_q_mi_per_h);
 
 static_assert(mile_per_hour::symbol == "mi/h");
 
diff --git a/test_package/test_package.cpp b/test_package/test_package.cpp
index 86df020c..eb2cd2b8 100644
--- a/test_package/test_package.cpp
+++ b/test_package/test_package.cpp
@@ -33,5 +33,5 @@ constexpr Speed auto avg_speed(Length auto d, Time auto t)
 int main()
 {
   using namespace units::physical::si::literals;
-  std::cout << "Average speed = " << avg_speed(240.q_km, 2q_h) << '\n';
+  std::cout << "Average speed = " << avg_speed(240._q_km, 2_q_h) << '\n';
 }