From c69bd140b201f92d46407a7237416923a909734e Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Thu, 6 Jun 2024 13:18:45 +0200
Subject: [PATCH] refactor: all units made `final`

---
 .../framework_basics/design_overview.md       | 12 +--
 .../dimensionless_quantities.md               | 14 +--
 .../faster_than_lightspeed_constants.md       |  4 +-
 .../interface_introduction.md                 | 10 +-
 .../framework_basics/systems_of_units.md      | 20 ++--
 .../framework_basics/text_output.md           | 36 +++----
 .../framework_basics/the_affine_space.md      |  6 +-
 .../framework_basics/value_conversions.md     | 12 +--
 example/currency.cpp                          |  8 +-
 .../mp-units/framework/system_reference.h     |  8 +-
 src/core/include/mp-units/framework/unit.h    | 24 ++---
 .../include/mp-units/systems/angular/units.h  | 10 +-
 src/systems/include/mp-units/systems/cgs.h    | 14 +--
 src/systems/include/mp-units/systems/hep.h    |  8 +-
 src/systems/include/mp-units/systems/iau.h    | 26 ++---
 .../systems/iec80000/binary_prefixes.h        | 16 +--
 .../include/mp-units/systems/iec80000/units.h | 10 +-
 .../include/mp-units/systems/imperial.h       | 42 ++++----
 .../include/mp-units/systems/international.h  | 38 +++----
 .../include/mp-units/systems/natural.h        |  2 +-
 .../include/mp-units/systems/si/constants.h   | 18 ++--
 .../include/mp-units/systems/si/prefixes.h    | 48 ++++-----
 .../include/mp-units/systems/si/units.h       | 82 ++++++++--------
 .../include/mp-units/systems/typographic.h    |  8 +-
 src/systems/include/mp-units/systems/usc.h    | 92 ++++++++---------
 test/runtime/truncation_test.cpp              |  2 +-
 test/static/dimension_test.cpp                |  2 +-
 test/static/quantity_point_test.cpp           |  2 +-
 test/static/quantity_spec_test.cpp            |  2 +-
 test/static/reference_test.cpp                | 34 +++----
 test/static/unit_test.cpp                     | 98 ++++++++++---------
 31 files changed, 357 insertions(+), 351 deletions(-)

diff --git a/docs/users_guide/framework_basics/design_overview.md b/docs/users_guide/framework_basics/design_overview.md
index da38cd95..8513ee80 100644
--- a/docs/users_guide/framework_basics/design_overview.md
+++ b/docs/users_guide/framework_basics/design_overview.md
@@ -234,13 +234,13 @@ A unit can be defined by the user in one of the following ways:
 template<PrefixableUnit U> struct kilo_ : prefixed_unit<"k", mag_power<10, 3>, U{}> {};
 template<PrefixableUnit auto U> inline constexpr kilo_<decltype(U)> kilo;
 
-inline constexpr struct second : named_unit<"s", kind_of<isq::time>> {} second;
-inline constexpr struct minute : named_unit<"min", mag<60> * second> {} minute;
-inline constexpr struct gram : named_unit<"g", kind_of<isq::mass>> {} gram;
-inline constexpr struct kilogram : decltype(kilo<gram>) {} kilogram;
-inline constexpr struct newton : named_unit<"N", kilogram * metre / square(second)> {} newton;
+inline constexpr struct second final : named_unit<"s", kind_of<isq::time>> {} second;
+inline constexpr struct minute final : named_unit<"min", mag<60> * second> {} minute;
+inline constexpr struct gram   final : named_unit<"g", kind_of<isq::mass>> {} gram;
+inline constexpr auto kilogram = kilo<gram>;
+inline constexpr struct newton final : named_unit<"N", kilogram * metre / square(second)> {} newton;
 
-inline constexpr struct speed_of_light_in_vacuum : named_unit<"c", mag<299'792'458> * metre / second> {} speed_of_light_in_vacuum;
+inline constexpr struct speed_of_light_in_vacuum final : named_unit<"c", mag<299'792'458> * metre / second> {} speed_of_light_in_vacuum;
 ```
 
 The [unit equation](../../appendix/glossary.md#unit-equation) of `si::metre / si::second` results
diff --git a/docs/users_guide/framework_basics/dimensionless_quantities.md b/docs/users_guide/framework_basics/dimensionless_quantities.md
index 3019828f..05bbca18 100644
--- a/docs/users_guide/framework_basics/dimensionless_quantities.md
+++ b/docs/users_guide/framework_basics/dimensionless_quantities.md
@@ -113,7 +113,7 @@ that uses a unit that is proportional to the ratio of kilometers per megaparsecs
 units of _length_:
 
 ```cpp
-inline constexpr struct hubble_constant :
+inline constexpr struct hubble_constant final :
     named_unit<{u8"H₀", "H_0"}, mag_ratio<701, 10> * si::kilo<si::metre> / si::second / si::mega<parsec>> {} hubble_constant;
 ```
 
@@ -158,9 +158,9 @@ Besides the unit `one`, there are a few other scaled units predefined in the lib
 with dimensionless quantities:
 
 ```cpp
-inline constexpr struct percent : named_unit<"%", mag_ratio<1, 100> * one> {} percent;
-inline constexpr struct per_mille : named_unit<{u8"‰", "%o"}, mag_ratio<1, 1000> * one> {} per_mille;
-inline constexpr struct parts_per_million : named_unit<"ppm", mag_ratio<1, 1'000'000> * one> {} parts_per_million;
+inline constexpr struct percent final : named_unit<"%", mag_ratio<1, 100> * one> {} percent;
+inline constexpr struct per_mille final : named_unit<{u8"‰", "%o"}, mag_ratio<1, 1000> * one> {} per_mille;
+inline constexpr struct parts_per_million final : named_unit<"ppm", mag_ratio<1, 1'000'000> * one> {} parts_per_million;
 inline constexpr auto ppm = parts_per_million;
 ```
 
@@ -242,9 +242,9 @@ With the above, we can constrain `radian`, `steradian`, and `bit` to be allowed
 specific quantity kinds only:
 
 ```cpp
-inline constexpr struct radian : named_unit<"rad", metre / metre, kind_of<isq::angular_measure>> {} radian;
-inline constexpr struct steradian : named_unit<"sr", square(metre) / square(metre), kind_of<isq::solid_angular_measure>> {} steradian;
-inline constexpr struct bit : named_unit<"bit", one, kind_of<storage_capacity>> {} bit;
+inline constexpr struct radian final : named_unit<"rad", metre / metre, kind_of<isq::angular_measure>> {} radian;
+inline constexpr struct steradian final : named_unit<"sr", square(metre) / square(metre), kind_of<isq::solid_angular_measure>> {} steradian;
+inline constexpr struct bit final : named_unit<"bit", one, kind_of<storage_capacity>> {} bit;
 ```
 
 but still allow the usage of `one` and its scaled versions for such quantities.
diff --git a/docs/users_guide/framework_basics/faster_than_lightspeed_constants.md b/docs/users_guide/framework_basics/faster_than_lightspeed_constants.md
index d69ef39c..cef490db 100644
--- a/docs/users_guide/framework_basics/faster_than_lightspeed_constants.md
+++ b/docs/users_guide/framework_basics/faster_than_lightspeed_constants.md
@@ -39,12 +39,12 @@ namespace si {
 
 namespace si2019 {
 
-inline constexpr struct speed_of_light_in_vacuum :
+inline constexpr struct speed_of_light_in_vacuum final :
   named_unit<"c", mag<299'792'458> * metre / second> {} speed_of_light_in_vacuum;
 
 }  // namespace si2019
 
-inline constexpr struct magnetic_constant :
+inline constexpr struct magnetic_constant final :
   named_unit<{u8"μ₀", "u_0"}, mag<4> * mag_pi * mag_power<10, -7> * henry / metre> {} magnetic_constant;
 
 }  // namespace mp_units::si
diff --git a/docs/users_guide/framework_basics/interface_introduction.md b/docs/users_guide/framework_basics/interface_introduction.md
index f1bcc16f..9f3de85c 100644
--- a/docs/users_guide/framework_basics/interface_introduction.md
+++ b/docs/users_guide/framework_basics/interface_introduction.md
@@ -6,8 +6,8 @@ The **mp-units** library decided to use a rather unusual pattern to define entit
 Here is how we define `metre` and `second` [SI](../../appendix/glossary.md#si) base units:
 
 ```cpp
-inline constexpr struct metre : named_unit<"m", kind_of<isq::length>> {} metre;
-inline constexpr struct second : named_unit<"s", kind_of<isq::time>> {} second;
+inline constexpr struct metre final : named_unit<"m", kind_of<isq::length>> {} metre;
+inline constexpr struct second final : named_unit<"s", kind_of<isq::time>> {} second;
 ```
 
 Please note that the above reuses the same identifier for a type and its value. The rationale
@@ -94,9 +94,9 @@ the value-based [unit equation](../../appendix/glossary.md#unit-equation) to a c
 definition:
 
 ```cpp
-inline constexpr struct newton : named_unit<"N", kilogram * metre / square(second)> {} newton;
-inline constexpr struct pascal : named_unit<"Pa", newton / square(metre)> {} pascal;
-inline constexpr struct joule : named_unit<"J", newton * metre> {} joule;
+inline constexpr struct newton final : named_unit<"N", kilogram * metre / square(second)> {} newton;
+inline constexpr struct pascal final : named_unit<"Pa", newton / square(metre)> {} pascal;
+inline constexpr struct joule  final : named_unit<"J", newton * metre> {} joule;
 ```
 
 
diff --git a/docs/users_guide/framework_basics/systems_of_units.md b/docs/users_guide/framework_basics/systems_of_units.md
index 3d263c11..df37b6bf 100644
--- a/docs/users_guide/framework_basics/systems_of_units.md
+++ b/docs/users_guide/framework_basics/systems_of_units.md
@@ -26,7 +26,7 @@ this is expressed by associating a quantity kind (that we discussed in detail in
 previous chapter) with a unit that is used to express it:
 
 ```cpp
-inline constexpr struct metre : named_unit<"m", kind_of<isq::length>> {} metre;
+inline constexpr struct metre final : named_unit<"m", kind_of<isq::length>> {} metre;
 ```
 
 !!! important
@@ -67,7 +67,7 @@ of a specific predefined [unit equation](../../appendix/glossary.md#unit-equatio
 For example, a unit of _power_ quantity is defined in the library as:
 
 ```cpp
-inline constexpr struct watt : named_unit<"W", joule / second> {} watt;
+inline constexpr struct watt final : named_unit<"W", joule / second> {} watt;
 ```
 
 However, a _power_ quantity can be expressed in other units as well. For example,
@@ -110,8 +110,8 @@ The library allows constraining such units to work only with quantities of a spe
 the following way:
 
 ```cpp
-inline constexpr struct hertz : named_unit<"Hz", one / second, kind_of<isq::frequency>> {} hertz;
-inline constexpr struct becquerel : named_unit<"Bq", one / second, kind_of<isq::activity>> {} becquerel;
+inline constexpr struct hertz final : named_unit<"Hz", one / second, kind_of<isq::frequency>> {} hertz;
+inline constexpr struct becquerel final : named_unit<"Bq", one / second, kind_of<isq::activity>> {} becquerel;
 ```
 
 With the above, `hertz` can only be used with _frequencies_, while `becquerel` should only be used with
@@ -168,25 +168,25 @@ be explicitly expressed with predefined SI prefixes. Those include units like mi
 electronvolt:
 
 ```cpp
-inline constexpr struct minute : named_unit<"min", mag<60> * si::second> {} minute;
-inline constexpr struct hour : named_unit<"h", mag<60> * minute> {} hour;
-inline constexpr struct electronvolt : named_unit<"eV", mag_ratio<1'602'176'634, 1'000'000'000> * mag_power<10, -19> * si::joule> {} electronvolt;
+inline constexpr struct minute final : named_unit<"min", mag<60> * si::second> {} minute;
+inline constexpr struct hour final : named_unit<"h", mag<60> * minute> {} hour;
+inline constexpr struct electronvolt final : named_unit<"eV", mag_ratio<1'602'176'634, 1'000'000'000> * mag_power<10, -19> * si::joule> {} electronvolt;
 ```
 
 Also, units of other [systems of units](../../appendix/glossary.md#system-of-units) are often defined
 in terms of scaled versions of the SI units. For example, the international yard is defined as:
 
 ```cpp
-inline constexpr struct yard : named_unit<"yd", mag_ratio<9'144, 10'000> * si::metre> {} yard;
+inline constexpr struct yard final : named_unit<"yd", mag_ratio<9'144, 10'000> * si::metre> {} yard;
 ```
 
 For some units, a magnitude might also be irrational. The best example here is a `degree` which
 is defined using a floating-point magnitude having a factor of the number π (Pi):
 
 ```cpp
-inline constexpr struct mag_pi : magnitude<std::numbers::pi_v<long double>> {} mag_pi;
+inline constexpr struct mag_pi final : magnitude<std::numbers::pi_v<long double>> {} mag_pi;
 ```
 
 ```cpp
-inline constexpr struct degree : named_unit<{u8"°", "deg"}, mag_pi / mag<180> * si::radian> {} degree;
+inline constexpr struct degree final : named_unit<{u8"°", "deg"}, mag_pi / mag<180> * si::radian> {} degree;
 ```
diff --git a/docs/users_guide/framework_basics/text_output.md b/docs/users_guide/framework_basics/text_output.md
index 67bd4395..6487640e 100644
--- a/docs/users_guide/framework_basics/text_output.md
+++ b/docs/users_guide/framework_basics/text_output.md
@@ -45,18 +45,18 @@ and units of derived quantities.
 === "Units"
 
     ```cpp
-    inline constexpr struct second : named_unit<"s", kind_of<isq::time>> {} second;
-    inline constexpr struct metre : named_unit<"m", kind_of<isq::length>> {} metre;
-    inline constexpr struct gram : named_unit<"g", kind_of<isq::mass>> {} gram;
+    inline constexpr struct second final : named_unit<"s", kind_of<isq::time>> {} second;
+    inline constexpr struct metre final : named_unit<"m", kind_of<isq::length>> {} metre;
+    inline constexpr struct gram final : named_unit<"g", kind_of<isq::mass>> {} gram;
     inline constexpr auto kilogram = kilo<gram>;
 
-    inline constexpr struct newton : named_unit<"N", kilogram * metre / square(second)> {} newton;
-    inline constexpr struct joule : named_unit<"J", newton * metre> {} joule;
-    inline constexpr struct watt : named_unit<"W", joule / second> {} watt;
-    inline constexpr struct coulomb : named_unit<"C", ampere * second> {} coulomb;
-    inline constexpr struct volt : named_unit<"V", watt / ampere> {} volt;
-    inline constexpr struct farad : named_unit<"F", coulomb / volt> {} farad;
-    inline constexpr struct ohm : named_unit<{u8"Ω", "ohm"}, volt / ampere> {} ohm;
+    inline constexpr struct newton final : named_unit<"N", kilogram * metre / square(second)> {} newton;
+    inline constexpr struct joule final : named_unit<"J", newton * metre> {} joule;
+    inline constexpr struct watt final : named_unit<"W", joule / second> {} watt;
+    inline constexpr struct coulomb final : named_unit<"C", ampere * second> {} coulomb;
+    inline constexpr struct volt final : named_unit<"V", watt / ampere> {} volt;
+    inline constexpr struct farad final : named_unit<"F", coulomb / volt> {} farad;
+    inline constexpr struct ohm final : named_unit<{u8"Ω", "ohm"}, volt / ampere> {} ohm;
     ```
 
 === "Prefixes"
@@ -75,13 +75,13 @@ and units of derived quantities.
 === "Constants"
 
     ```cpp
-    inline constexpr struct hyperfine_structure_transition_frequency_of_cs : named_unit<{u8"Δν_Cs", "dv_Cs"}, mag<9'192'631'770> * hertz> {} hyperfine_structure_transition_frequency_of_cs;
-    inline constexpr struct speed_of_light_in_vacuum : named_unit<"c", mag<299'792'458> * metre / second> {} speed_of_light_in_vacuum;
-    inline constexpr struct planck_constant : named_unit<"h", mag_ratio<662'607'015, 100'000'000> * mag_power<10, -34> * joule * second> {} planck_constant;
-    inline constexpr struct elementary_charge : named_unit<"e", mag_ratio<1'602'176'634, 1'000'000'000> * mag_power<10, -19> * coulomb> {} elementary_charge;
-    inline constexpr struct boltzmann_constant : named_unit<"k", mag_ratio<1'380'649, 1'000'000> * mag_power<10, -23> * joule / kelvin> {} boltzmann_constant;
-    inline constexpr struct avogadro_constant : named_unit<"N_A", mag_ratio<602'214'076, 100'000'000> * mag_power<10, 23> / mole> {} avogadro_constant;
-    inline constexpr struct luminous_efficacy : named_unit<"K_cd", mag<683> * lumen / watt> {} luminous_efficacy;
+    inline constexpr struct hyperfine_structure_transition_frequency_of_cs final : named_unit<{u8"Δν_Cs", "dv_Cs"}, mag<9'192'631'770> * hertz> {} hyperfine_structure_transition_frequency_of_cs;
+    inline constexpr struct speed_of_light_in_vacuum final : named_unit<"c", mag<299'792'458> * metre / second> {} speed_of_light_in_vacuum;
+    inline constexpr struct planck_constant final : named_unit<"h", mag_ratio<662'607'015, 100'000'000> * mag_power<10, -34> * joule * second> {} planck_constant;
+    inline constexpr struct elementary_charge final : named_unit<"e", mag_ratio<1'602'176'634, 1'000'000'000> * mag_power<10, -19> * coulomb> {} elementary_charge;
+    inline constexpr struct boltzmann_constant final : named_unit<"k", mag_ratio<1'380'649, 1'000'000> * mag_power<10, -23> * joule / kelvin> {} boltzmann_constant;
+    inline constexpr struct avogadro_constant final : named_unit<"N_A", mag_ratio<602'214'076, 100'000'000> * mag_power<10, 23> / mole> {} avogadro_constant;
+    inline constexpr struct luminous_efficacy final : named_unit<"K_cd", mag<683> * lumen / watt> {} luminous_efficacy;
     ```
 
 !!! important
@@ -105,7 +105,7 @@ and units of derived quantities.
     template name to initialize it with two symbols:
 
     ```cpp
-    inline constexpr struct ohm : named_unit<symbol_text{u8"Ω", "ohm"}, volt / ampere> {} ohm;
+    inline constexpr struct ohm final : named_unit<symbol_text{u8"Ω", "ohm"}, volt / ampere> {} ohm;
     ```
 
 
diff --git a/docs/users_guide/framework_basics/the_affine_space.md b/docs/users_guide/framework_basics/the_affine_space.md
index c21bceea..5ed28660 100644
--- a/docs/users_guide/framework_basics/the_affine_space.md
+++ b/docs/users_guide/framework_basics/the_affine_space.md
@@ -426,16 +426,16 @@ definitions:
 ```cpp
 namespace si {
 
-inline constexpr struct kelvin :
+inline constexpr struct kelvin final :
     named_unit<"K", kind_of<isq::thermodynamic_temperature>, zeroth_kelvin> {} kelvin;
-inline constexpr struct degree_Celsius :
+inline constexpr struct degree_Celsius final :
     named_unit<{u8"°C", "`C"}, kelvin, zeroth_degree_Celsius> {} degree_Celsius;
 
 }
 
 namespace usc {
 
-inline constexpr struct degree_Fahrenheit :
+inline constexpr struct degree_Fahrenheit final :
     named_unit<{u8"°F", "`F"}, mag_ratio<5, 9> * si::degree_Celsius,
                zeroth_degree_Fahrenheit> {} degree_Fahrenheit;
 
diff --git a/docs/users_guide/framework_basics/value_conversions.md b/docs/users_guide/framework_basics/value_conversions.md
index bed6e928..ecc6d6c9 100644
--- a/docs/users_guide/framework_basics/value_conversions.md
+++ b/docs/users_guide/framework_basics/value_conversions.md
@@ -88,8 +88,8 @@ the `value_cast<U, Rep>(q)` which always returns the most precise result:
     inline constexpr struct dim_currency : base_dimension<"$"> {} dim_currency;
     inline constexpr struct currency : quantity_spec<dim_currency> {} currency;
 
-    inline constexpr struct us_dollar : named_unit<"USD", kind_of<currency>> {} us_dollar;
-    inline constexpr struct scaled_us_dollar : named_unit<"USD_s", mag_power<10, -8> * us_dollar> {} scaled_us_dollar;
+    inline constexpr struct us_dollar final : named_unit<"USD", kind_of<currency>> {} us_dollar;
+    inline constexpr struct scaled_us_dollar final : named_unit<"USD_s", mag_power<10, -8> * us_dollar> {} scaled_us_dollar;
 
     namespace unit_symbols {
 
@@ -108,8 +108,8 @@ the `value_cast<U, Rep>(q)` which always returns the most precise result:
     inline constexpr struct dim_currency : base_dimension<"$"> {} dim_currency;
     inline constexpr struct currency : quantity_spec<currency, dim_currency> {} currency;
 
-    inline constexpr struct us_dollar : named_unit<"USD", kind_of<currency>> {} us_dollar;
-    inline constexpr struct scaled_us_dollar : named_unit<"USD_s", mag_power<10, -8> * us_dollar> {} scaled_us_dollar;
+    inline constexpr struct us_dollar final : named_unit<"USD", kind_of<currency>> {} us_dollar;
+    inline constexpr struct scaled_us_dollar final : named_unit<"USD_s", mag_power<10, -8> * us_dollar> {} scaled_us_dollar;
 
     namespace unit_symbols {
 
@@ -128,8 +128,8 @@ the `value_cast<U, Rep>(q)` which always returns the most precise result:
     inline constexpr struct dim_currency : base_dimension<"$"> {} dim_currency;
     QUANTITY_SPEC(currency, dim_currency);
 
-    inline constexpr struct us_dollar : named_unit<"USD", kind_of<currency>> {} us_dollar;
-    inline constexpr struct scaled_us_dollar : named_unit<"USD_s", mag_power<10, -8> * us_dollar> {} scaled_us_dollar;
+    inline constexpr struct us_dollar final : named_unit<"USD", kind_of<currency>> {} us_dollar;
+    inline constexpr struct scaled_us_dollar final : named_unit<"USD_s", mag_power<10, -8> * us_dollar> {} scaled_us_dollar;
 
     namespace unit_symbols {
 
diff --git a/example/currency.cpp b/example/currency.cpp
index a638fe86..bbbb55cf 100644
--- a/example/currency.cpp
+++ b/example/currency.cpp
@@ -40,10 +40,10 @@ inline constexpr struct dim_currency : base_dimension<"$"> {} dim_currency;
 
 QUANTITY_SPEC(currency, dim_currency);
 
-inline constexpr struct euro : named_unit<"EUR", kind_of<currency>> {} euro;
-inline constexpr struct us_dollar : named_unit<"USD", kind_of<currency>> {} us_dollar;
-inline constexpr struct great_british_pound : named_unit<"GBP", kind_of<currency>> {} great_british_pound;
-inline constexpr struct japanese_jen : named_unit<"JPY", kind_of<currency>> {} japanese_jen;
+inline constexpr struct euro final : named_unit<"EUR", kind_of<currency>> {} euro;
+inline constexpr struct us_dollar final : named_unit<"USD", kind_of<currency>> {} us_dollar;
+inline constexpr struct great_british_pound final : named_unit<"GBP", kind_of<currency>> {} great_british_pound;
+inline constexpr struct japanese_jen final : named_unit<"JPY", kind_of<currency>> {} japanese_jen;
 // clang-format on
 
 namespace unit_symbols {
diff --git a/src/core/include/mp-units/framework/system_reference.h b/src/core/include/mp-units/framework/system_reference.h
index b4c202ec..5718cb1a 100644
--- a/src/core/include/mp-units/framework/system_reference.h
+++ b/src/core/include/mp-units/framework/system_reference.h
@@ -45,10 +45,10 @@ namespace mp_units {
  * @code{.cpp}
  * // hypothetical natural system of units for c=1
  *
- * inline constexpr struct second : named_unit<"s"> {} second;
- * inline constexpr struct minute : named_unit<"min", mag<60> * second> {} minute;
- * inline constexpr struct gram : named_unit<"g"> {} gram;
- * inline constexpr struct kilogram : decltype(si::kilo<gram>) {} kilogram;
+ * inline constexpr struct second final : named_unit<"s"> {} second;
+ * inline constexpr struct minute final : named_unit<"min", mag<60> * second> {} minute;
+ * inline constexpr struct gram final : named_unit<"g"> {} gram;
+ * inline constexpr auto kilogram = si::kilo<gram>;
  *
  * inline constexpr struct time : system_reference<isq::time, second> {} time;
  * inline constexpr struct length : system_reference<isq::length, second> {} length;
diff --git a/src/core/include/mp-units/framework/unit.h b/src/core/include/mp-units/framework/unit.h
index 7d5a7f07..5cc51d63 100644
--- a/src/core/include/mp-units/framework/unit.h
+++ b/src/core/include/mp-units/framework/unit.h
@@ -104,12 +104,12 @@ inline constexpr bool is_specialization_of_scaled_unit<scaled_unit<M, U>> = true
  * For example:
  *
  * @code{.cpp}
- * inline constexpr struct second : named_unit<"s", time> {} second;
- * inline constexpr struct metre : named_unit<"m", length> {} metre;
- * inline constexpr struct hertz : named_unit<"Hz", inverse(second)> {} hertz;
- * inline constexpr struct newton : named_unit<"N", kilogram * metre / square(second)> {} newton;
- * inline constexpr struct degree_Celsius : named_unit<{u8"°C", "`C"}, kelvin> {} degree_Celsius;
- * inline constexpr struct minute : named_unit<"min", mag<60> * second> {} minute;
+ * inline constexpr struct second final : named_unit<"s", kind_of<time>> {} second;
+ * inline constexpr struct metre final : named_unit<"m", kind_of<length> {} metre;
+ * inline constexpr struct hertz final : named_unit<"Hz", inverse(second), kind_of<frequency>> {} hertz;
+ * inline constexpr struct newton final : named_unit<"N", kilogram * metre / square(second)> {} newton;
+ * inline constexpr struct degree_Celsius final : named_unit<{u8"°C", "`C"}, kelvin, zeroth_degree_Celsius> {}
+ * degree_Celsius; inline constexpr struct minute final : named_unit<"min", mag<60> * second> {} minute;
  * @endcode
  *
  * @note A common convention in this library is to assign the same name for a type and an object of this type.
@@ -236,7 +236,7 @@ struct named_unit<Symbol, U, QS, PO> : decltype(U)::_base_type_ {
  * template<PrefixableUnit auto U>
  * inline constexpr kilo_<U> kilo;
  *
- * inline constexpr struct kilogram : decltype(si::kilo<gram>) {} kilogram;
+ * inline constexpr auto kilogram = si::kilo<gram>;
  * @endcode
  *
  * @tparam Symbol a prefix text to prepend to a unit symbol
@@ -308,7 +308,7 @@ struct derived_unit_impl : detail::expr_fractions<detail::is_one, Expr...> {
  *       instantiate this type automatically based on the unit arithmetic equation provided by the user.
  */
 template<detail::DerivedUnitExpr... Expr>
-struct derived_unit : detail::derived_unit_impl<Expr...> {};
+struct derived_unit final : detail::derived_unit_impl<Expr...> {};
 
 /**
  * @brief Unit one
@@ -316,7 +316,7 @@ struct derived_unit : detail::derived_unit_impl<Expr...> {};
  * Unit of a dimensionless quantity.
  */
 // clang-format off
-MP_UNITS_EXPORT inline constexpr struct one : detail::derived_unit_impl<> {} one;
+MP_UNITS_EXPORT inline constexpr struct one final : detail::derived_unit_impl<> {} one;
 // clang-format on
 
 namespace detail {
@@ -595,9 +595,9 @@ template<std::intmax_t Num, std::intmax_t Den = 1, Unit U>
 
 // common dimensionless units
 // clang-format off
-inline constexpr struct percent : named_unit<"%", mag_ratio<1, 100> * one> {} percent;
-inline constexpr struct per_mille : named_unit<symbol_text{u8"‰", "%o"}, mag_ratio<1, 1000> * one> {} per_mille;
-inline constexpr struct parts_per_million : named_unit<"ppm", mag_ratio<1, 1'000'000> * one> {} parts_per_million;
+inline constexpr struct percent final : named_unit<"%", mag_ratio<1, 100> * one> {} percent;
+inline constexpr struct per_mille final : named_unit<symbol_text{u8"‰", "%o"}, mag_ratio<1, 1000> * one> {} per_mille;
+inline constexpr struct parts_per_million final : named_unit<"ppm", mag_ratio<1, 1'000'000> * one> {} parts_per_million;
 inline constexpr auto ppm = parts_per_million;
 // clang-format on
 
diff --git a/src/systems/include/mp-units/systems/angular/units.h b/src/systems/include/mp-units/systems/angular/units.h
index f0de3ead..e4747007 100644
--- a/src/systems/include/mp-units/systems/angular/units.h
+++ b/src/systems/include/mp-units/systems/angular/units.h
@@ -38,11 +38,11 @@ inline constexpr struct dim_angle : base_dimension<"A"> {} dim_angle;
 QUANTITY_SPEC(angle, dim_angle);
 QUANTITY_SPEC(solid_angle, pow<2>(angle));
 
-inline constexpr struct radian : named_unit<"rad", kind_of<angle>> {} radian;
-inline constexpr struct revolution : named_unit<"rev", mag<2> * mag_pi * radian> {} revolution;
-inline constexpr struct degree : named_unit<symbol_text{u8"°", "deg"}, mag_ratio<1, 360> * revolution> {} degree;
-inline constexpr struct gradian : named_unit<symbol_text{u8"ᵍ", "grad"}, mag_ratio<1, 400> * revolution> {} gradian;
-inline constexpr struct steradian : named_unit<"sr", square(radian)> {} steradian;
+inline constexpr struct radian final : named_unit<"rad", kind_of<angle>> {} radian;
+inline constexpr struct revolution final : named_unit<"rev", mag<2> * mag_pi * radian> {} revolution;
+inline constexpr struct degree final : named_unit<symbol_text{u8"°", "deg"}, mag_ratio<1, 360> * revolution> {} degree;
+inline constexpr struct gradian final : named_unit<symbol_text{u8"ᵍ", "grad"}, mag_ratio<1, 400> * revolution> {} gradian;
+inline constexpr struct steradian final : named_unit<"sr", square(radian)> {} steradian;
 // clang-format on
 
 namespace unit_symbols {
diff --git a/src/systems/include/mp-units/systems/cgs.h b/src/systems/include/mp-units/systems/cgs.h
index 4a3645f5..9ae0d265 100644
--- a/src/systems/include/mp-units/systems/cgs.h
+++ b/src/systems/include/mp-units/systems/cgs.h
@@ -38,13 +38,13 @@ namespace mp_units::cgs {
 inline constexpr auto centimetre = si::centi<si::metre>;
 inline constexpr auto gram = si::gram;
 inline constexpr auto second = si::second;
-inline constexpr struct gal : named_unit<"Gal", centimetre / square(second)> {} gal;
-inline constexpr struct dyne : named_unit<"dyn", gram * centimetre / square(second)> {} dyne;
-inline constexpr struct erg : named_unit<"erg", dyne * centimetre> {} erg;
-inline constexpr struct barye : named_unit<"Ba", gram / (centimetre * square(second))> {} barye;
-inline constexpr struct poise : named_unit<"P", gram / (centimetre * second)> {} poise;
-inline constexpr struct stokes : named_unit<"St", square(centimetre) / second> {} stokes;
-inline constexpr struct kayser : named_unit<"K", one / centimetre> {} kayser;
+inline constexpr struct gal final : named_unit<"Gal", centimetre / square(second)> {} gal;
+inline constexpr struct dyne final : named_unit<"dyn", gram * centimetre / square(second)> {} dyne;
+inline constexpr struct erg final : named_unit<"erg", dyne * centimetre> {} erg;
+inline constexpr struct barye final : named_unit<"Ba", gram / (centimetre * square(second))> {} barye;
+inline constexpr struct poise final : named_unit<"P", gram / (centimetre * second)> {} poise;
+inline constexpr struct stokes final : named_unit<"St", square(centimetre) / second> {} stokes;
+inline constexpr struct kayser final : named_unit<"K", one / centimetre> {} kayser;
 // clang-format on
 
 namespace unit_symbols {
diff --git a/src/systems/include/mp-units/systems/hep.h b/src/systems/include/mp-units/systems/hep.h
index 6020d07f..77f6a516 100644
--- a/src/systems/include/mp-units/systems/hep.h
+++ b/src/systems/include/mp-units/systems/hep.h
@@ -49,12 +49,12 @@ using si::electronvolt;
 // effective cross-sectional area according to EU council directive 80/181/EEC
 // https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:01980L0181-20090527#page=10
 // https://www.fedlex.admin.ch/eli/cc/1994/3109_3109_3109/de
-inline constexpr struct barn : named_unit<"b", mag_power<10, -28> * square(si::metre)> {} barn;
+inline constexpr struct barn final : named_unit<"b", mag_power<10, -28> * square(si::metre)> {} barn;
 
 // mass
-inline constexpr struct electron_mass : named_unit<"m_e", mag_ratio<9'109'383'701'528, 1'000'000'000'000> * mag_power<10, -31> * si::kilogram> {} electron_mass;
-inline constexpr struct proton_mass : named_unit<"m_p", mag_ratio<1'672'621'923'695, 1'000'000'000'000> * mag_power<10, -27> * si::kilogram> {} proton_mass;
-inline constexpr struct neutron_mass : named_unit<"m_n", mag_ratio<1'674'927'498'049, 1'000'000'000'000> * mag_power<10, -27> * si::kilogram> {} neutron_mass;
+inline constexpr struct electron_mass final : named_unit<"m_e", mag_ratio<9'109'383'701'528, 1'000'000'000'000> * mag_power<10, -31> * si::kilogram> {} electron_mass;
+inline constexpr struct proton_mass final : named_unit<"m_p", mag_ratio<1'672'621'923'695, 1'000'000'000'000> * mag_power<10, -27> * si::kilogram> {} proton_mass;
+inline constexpr struct neutron_mass final : named_unit<"m_n", mag_ratio<1'674'927'498'049, 1'000'000'000'000> * mag_power<10, -27> * si::kilogram> {} neutron_mass;
 
 // speed
 inline constexpr auto speed_of_light = si::si2019::speed_of_light_in_vacuum;
diff --git a/src/systems/include/mp-units/systems/iau.h b/src/systems/include/mp-units/systems/iau.h
index 804f2ed0..c81777aa 100644
--- a/src/systems/include/mp-units/systems/iau.h
+++ b/src/systems/include/mp-units/systems/iau.h
@@ -39,43 +39,43 @@ namespace mp_units::iau {
 
 // clang-format off
 // time
-inline constexpr struct day : named_unit<"D", si::day> {} day;
-inline constexpr struct Julian_year : named_unit<"a", mag_ratio<365'25, 100> * day> {} Julian_year;
+inline constexpr struct day final : named_unit<"D", si::day> {} day;
+inline constexpr struct Julian_year final : named_unit<"a", mag_ratio<365'25, 100> * day> {} Julian_year;
 
 // mass
 // https://en.wikipedia.org/wiki/Solar_mass
 // TODO What is the official mass of sun (every source in the Internet provides a different value)
-inline constexpr struct solar_mass : named_unit<symbol_text{u8"M_☉", "M_SUN"}, mag_ratio<198'847, 100'000> * mag_power<10, 30> * si::kilogram> {} solar_mass;
-inline constexpr struct Jupiter_mass : named_unit<"M_JUP", mag_ratio<1'898, 1'000> * mag_power<10, 27> * si::kilogram> {} Jupiter_mass;
-inline constexpr struct Earth_mass : named_unit<"M_EARTH", mag_ratio<59'742, 10'000> * mag_power<10, 24> * si::kilogram> {} Earth_mass;
+inline constexpr struct solar_mass final : named_unit<symbol_text{u8"M_☉", "M_SUN"}, mag_ratio<198'847, 100'000> * mag_power<10, 30> * si::kilogram> {} solar_mass;
+inline constexpr struct Jupiter_mass final : named_unit<"M_JUP", mag_ratio<1'898, 1'000> * mag_power<10, 27> * si::kilogram> {} Jupiter_mass;
+inline constexpr struct Earth_mass final : named_unit<"M_EARTH", mag_ratio<59'742, 10'000> * mag_power<10, 24> * si::kilogram> {} Earth_mass;
 
 // length
 inline constexpr auto astronomical_unit = si::astronomical_unit;
 
 // https://en.wikipedia.org/wiki/Lunar_distance_(astronomy)
-inline constexpr struct lunar_distance : named_unit<"LD", mag<384'399> * si::kilo<si::metre>> {} lunar_distance;
+inline constexpr struct lunar_distance final : named_unit<"LD", mag<384'399> * si::kilo<si::metre>> {} lunar_distance;
 
 // https://en.wikipedia.org/wiki/Light-year
-inline constexpr struct light_year : named_unit<"ly", mag<9'460'730'472'580'800> * si::metre> {} light_year;
+inline constexpr struct light_year final : named_unit<"ly", mag<9'460'730'472'580'800> * si::metre> {} light_year;
 
 // https://en.wikipedia.org/wiki/Parsec
-inline constexpr struct parsec : named_unit<"pc", astronomical_unit / (mag_ratio<1, 3600> * si::degree)> {} parsec;
+inline constexpr struct parsec final : named_unit<"pc", astronomical_unit / (mag_ratio<1, 3600> * si::degree)> {} parsec;
 
 // https://en.wikipedia.org/wiki/Angstrom
-inline constexpr struct angstrom : named_unit<symbol_text{u8"Å", "A"}, mag_power<10, -10> * si::metre> {} angstrom;
+inline constexpr struct angstrom final : named_unit<symbol_text{u8"Å", "A"}, mag_power<10, -10> * si::metre> {} angstrom;
 
 // selected constants
 // https://en.wikipedia.org/wiki/Astronomical_constant
-inline constexpr struct gaussian_gravitational_constant :
+inline constexpr struct gaussian_gravitational_constant final :
     named_unit<"k", mag_ratio<1'720'209'895, 100'000'000'000> * pow<3, 2>(astronomical_unit) / pow<1,2>(solar_mass) / day> {} gaussian_gravitational_constant;
 
-inline constexpr struct speed_of_light :
+inline constexpr struct speed_of_light final :
     named_unit<symbol_text{u8"c₀", "c_0"}, si::si2019::speed_of_light_in_vacuum> {} speed_of_light;
 
-inline constexpr struct constant_of_gravitation :
+inline constexpr struct constant_of_gravitation final :
     named_unit<"G", mag_ratio<667'430, 100'000> * mag_power<10, -11> * cubic(si::metre) / si::kilogram / square(si::second)> {} constant_of_gravitation;
 
-inline constexpr struct hubble_constant :
+inline constexpr struct hubble_constant final :
     named_unit<symbol_text{u8"H₀", "H_0"}, mag_ratio<701, 10> * si::kilo<si::metre> / si::second / si::mega<parsec>> {} hubble_constant;
 // clang-format on
 
diff --git a/src/systems/include/mp-units/systems/iec80000/binary_prefixes.h b/src/systems/include/mp-units/systems/iec80000/binary_prefixes.h
index 1f2e9660..5eb39132 100644
--- a/src/systems/include/mp-units/systems/iec80000/binary_prefixes.h
+++ b/src/systems/include/mp-units/systems/iec80000/binary_prefixes.h
@@ -31,14 +31,14 @@
 namespace mp_units::iec80000 {
 
 // clang-format off
-template<PrefixableUnit U> struct kibi_ : prefixed_unit<"Ki", mag_power<2, 10>, U{}> {};
-template<PrefixableUnit U> struct mebi_ : prefixed_unit<"Mi", mag_power<2, 20>, U{}> {};
-template<PrefixableUnit U> struct gibi_ : prefixed_unit<"Gi", mag_power<2, 30>, U{}> {};
-template<PrefixableUnit U> struct tebi_ : prefixed_unit<"Ti", mag_power<2, 40>, U{}> {};
-template<PrefixableUnit U> struct pebi_ : prefixed_unit<"Pi", mag_power<2, 50>, U{}> {};
-template<PrefixableUnit U> struct exbi_ : prefixed_unit<"Ei", mag_power<2, 60>, U{}> {};
-template<PrefixableUnit U> struct zebi_ : prefixed_unit<"Zi", mag_power<2, 70>, U{}> {};
-template<PrefixableUnit U> struct yobi_ : prefixed_unit<"Yi", mag_power<2, 80>, U{}> {};
+template<PrefixableUnit U> struct kibi_ final : prefixed_unit<"Ki", mag_power<2, 10>, U{}> {};
+template<PrefixableUnit U> struct mebi_ final : prefixed_unit<"Mi", mag_power<2, 20>, U{}> {};
+template<PrefixableUnit U> struct gibi_ final : prefixed_unit<"Gi", mag_power<2, 30>, U{}> {};
+template<PrefixableUnit U> struct tebi_ final : prefixed_unit<"Ti", mag_power<2, 40>, U{}> {};
+template<PrefixableUnit U> struct pebi_ final : prefixed_unit<"Pi", mag_power<2, 50>, U{}> {};
+template<PrefixableUnit U> struct exbi_ final : prefixed_unit<"Ei", mag_power<2, 60>, U{}> {};
+template<PrefixableUnit U> struct zebi_ final : prefixed_unit<"Zi", mag_power<2, 70>, U{}> {};
+template<PrefixableUnit U> struct yobi_ final : prefixed_unit<"Yi", mag_power<2, 80>, U{}> {};
 
 MP_UNITS_EXPORT_BEGIN
 
diff --git a/src/systems/include/mp-units/systems/iec80000/units.h b/src/systems/include/mp-units/systems/iec80000/units.h
index 9dd80c38..4d1ee098 100644
--- a/src/systems/include/mp-units/systems/iec80000/units.h
+++ b/src/systems/include/mp-units/systems/iec80000/units.h
@@ -34,11 +34,11 @@ MP_UNITS_EXPORT
 namespace mp_units::iec80000 {
 
 // clang-format off
-inline constexpr struct erlang : named_unit<"E", kind_of<traffic_intensity>> {} erlang;
-inline constexpr struct bit : named_unit<"bit", one, kind_of<storage_capacity>> {} bit;
-inline constexpr struct octet : named_unit<"o", mag<8> * bit> {} octet;
-inline constexpr struct byte : named_unit<"B", mag<8> * bit> {} byte;
-inline constexpr struct baud : named_unit<"Bd", one / si::second, kind_of<modulation_rate>> {} baud;
+inline constexpr struct erlang final : named_unit<"E", kind_of<traffic_intensity>> {} erlang;
+inline constexpr struct bit final : named_unit<"bit", one, kind_of<storage_capacity>> {} bit;
+inline constexpr struct octet final : named_unit<"o", mag<8> * bit> {} octet;
+inline constexpr struct byte final : named_unit<"B", mag<8> * bit> {} byte;
+inline constexpr struct baud final : named_unit<"Bd", one / si::second, kind_of<modulation_rate>> {} baud;
 // clang-format on
 
 }  // namespace mp_units::iec80000
diff --git a/src/systems/include/mp-units/systems/imperial.h b/src/systems/include/mp-units/systems/imperial.h
index ffdd4002..8ba61e05 100644
--- a/src/systems/include/mp-units/systems/imperial.h
+++ b/src/systems/include/mp-units/systems/imperial.h
@@ -39,38 +39,38 @@ using namespace international;
 
 // clang-format off
 // https://en.wikipedia.org/wiki/Imperial_units#Length
-inline constexpr struct hand : named_unit<"hh", mag_ratio<1, 3> * foot> {} hand;
-inline constexpr struct barleycorn : named_unit<"Bc", mag_ratio<1, 3> * inch> {} barleycorn;
-inline constexpr struct thou : named_unit<"th", mag_ratio<1, 12'000> * foot> {} thou;
-inline constexpr struct chain : named_unit<"ch", mag<22> * yard> {} chain;
-inline constexpr struct furlong : named_unit<"fur", mag<10> * chain> {} furlong;
+inline constexpr struct hand final : named_unit<"hh", mag_ratio<1, 3> * foot> {} hand;
+inline constexpr struct barleycorn final : named_unit<"Bc", mag_ratio<1, 3> * inch> {} barleycorn;
+inline constexpr struct thou final : named_unit<"th", mag_ratio<1, 12'000> * foot> {} thou;
+inline constexpr struct chain final : named_unit<"ch", mag<22> * yard> {} chain;
+inline constexpr struct furlong final : named_unit<"fur", mag<10> * chain> {} furlong;
 
 // maritime units
-inline constexpr struct cable : named_unit<"cb", mag_ratio<1, 10> * nautical_mile> {} cable;
-inline constexpr struct fathom : named_unit<"ftm", mag_ratio<1, 1000> * nautical_mile> {} fathom;
+inline constexpr struct cable final : named_unit<"cb", mag_ratio<1, 10> * nautical_mile> {} cable;
+inline constexpr struct fathom final : named_unit<"ftm", mag_ratio<1, 1000> * nautical_mile> {} fathom;
 
 // survey
-inline constexpr struct link : named_unit<"li", mag_ratio<1, 100> * chain> {} link;
-inline constexpr struct rod : named_unit<"rd", mag<25> * link> {} rod;
+inline constexpr struct link final : named_unit<"li", mag_ratio<1, 100> * chain> {} link;
+inline constexpr struct rod final : named_unit<"rd", mag<25> * link> {} rod;
 
 // https://en.wikipedia.org/wiki/Imperial_units#Area
-inline constexpr struct perch : named_unit<"perch", square(rod)> {} perch;
-inline constexpr struct rood : named_unit<"rood", mag<40> * perch> {} rood;
-inline constexpr struct acre : named_unit<"acre", mag<4> * rood> {} acre;
+inline constexpr struct perch final : named_unit<"perch", square(rod)> {} perch;
+inline constexpr struct rood final : named_unit<"rood", mag<40> * perch> {} rood;
+inline constexpr struct acre final : named_unit<"acre", mag<4> * rood> {} acre;
 
 // https://en.wikipedia.org/wiki/Imperial_units#Volume
-inline constexpr struct gallon : named_unit<"gal", mag_ratio<454'609, 100'000> * si::litre> {} gallon;
-inline constexpr struct quart : named_unit<"qt", mag_ratio<1, 4> * gallon> {} quart;
-inline constexpr struct pint : named_unit<"pt", mag_ratio<1, 2> * quart> {} pint;
-inline constexpr struct gill : named_unit<"gi", mag_ratio<1, 4> * pint> {} gill;
-inline constexpr struct fluid_ounce : named_unit<"fl oz", mag_ratio<1, 5> * gill> {} fluid_ounce;
+inline constexpr struct gallon final : named_unit<"gal", mag_ratio<454'609, 100'000> * si::litre> {} gallon;
+inline constexpr struct quart final : named_unit<"qt", mag_ratio<1, 4> * gallon> {} quart;
+inline constexpr struct pint final : named_unit<"pt", mag_ratio<1, 2> * quart> {} pint;
+inline constexpr struct gill final : named_unit<"gi", mag_ratio<1, 4> * pint> {} gill;
+inline constexpr struct fluid_ounce final : named_unit<"fl oz", mag_ratio<1, 5> * gill> {} fluid_ounce;
 
 // https://en.wikipedia.org/wiki/Avoirdupois_system#Post-Elizabethan_units
 inline constexpr auto drachm = dram;
-inline constexpr struct stone : named_unit<"st", mag<14> * pound> {} stone;
-inline constexpr struct quarter : named_unit<"qr", mag<2> * stone> {} quarter;
-inline constexpr struct long_hundredweight : named_unit<"cwt", mag<8> * stone> {} long_hundredweight;
-inline constexpr struct ton : named_unit<"t", mag<2'240> * pound> {} ton;
+inline constexpr struct stone final : named_unit<"st", mag<14> * pound> {} stone;
+inline constexpr struct quarter final : named_unit<"qr", mag<2> * stone> {} quarter;
+inline constexpr struct long_hundredweight final : named_unit<"cwt", mag<8> * stone> {} long_hundredweight;
+inline constexpr struct ton final : named_unit<"t", mag<2'240> * pound> {} ton;
 inline constexpr auto long_ton = ton;
 // clang-format on
 
diff --git a/src/systems/include/mp-units/systems/international.h b/src/systems/include/mp-units/systems/international.h
index d4de6a31..1d5141f6 100644
--- a/src/systems/include/mp-units/systems/international.h
+++ b/src/systems/include/mp-units/systems/international.h
@@ -37,44 +37,44 @@ namespace mp_units::international {
 
 // clang-format off
 // mass
-inline constexpr struct pound : named_unit<"lb", mag_ratio<45'359'237, 100'000'000> * si::kilogram> {} pound;
-inline constexpr struct ounce : named_unit<"oz", mag_ratio<1, 16> * pound> {} ounce;
-inline constexpr struct dram : named_unit<"dr", mag_ratio<1, 16> * ounce> {} dram;
-inline constexpr struct grain : named_unit<"gr", mag_ratio<1, 7'000> * pound> {} grain;
+inline constexpr struct pound final : named_unit<"lb", mag_ratio<45'359'237, 100'000'000> * si::kilogram> {} pound;
+inline constexpr struct ounce final : named_unit<"oz", mag_ratio<1, 16> * pound> {} ounce;
+inline constexpr struct dram final : named_unit<"dr", mag_ratio<1, 16> * ounce> {} dram;
+inline constexpr struct grain final : named_unit<"gr", mag_ratio<1, 7'000> * pound> {} grain;
 
 // length
 // https://en.wikipedia.org/wiki/United_States_customary_units#Length
-inline constexpr struct yard : named_unit<"yd", mag_ratio<9'144, 10'000> * si::metre> {} yard;
-inline constexpr struct foot : named_unit<"ft", mag_ratio<1, 3> * yard> {} foot;
-inline constexpr struct inch : named_unit<"in", mag_ratio<1, 12> * foot> {} inch;
-inline constexpr struct pica : named_unit<"P", mag_ratio<1, 6> * inch> {} pica;
-inline constexpr struct point : named_unit<"p", mag_ratio<1, 12> * pica> {} point;
-inline constexpr struct mil : named_unit<"mil", mag_ratio<1, 1'000> * inch> {} mil;
-inline constexpr struct twip : named_unit<"twip", mag_ratio<1, 20> * point> {} twip;
-inline constexpr struct mile : named_unit<"mi", mag<1760> * yard> {} mile;
-inline constexpr struct league : named_unit<"le", mag<3> * mile> {} league;
+inline constexpr struct yard final : named_unit<"yd", mag_ratio<9'144, 10'000> * si::metre> {} yard;
+inline constexpr struct foot final : named_unit<"ft", mag_ratio<1, 3> * yard> {} foot;
+inline constexpr struct inch final : named_unit<"in", mag_ratio<1, 12> * foot> {} inch;
+inline constexpr struct pica final : named_unit<"P", mag_ratio<1, 6> * inch> {} pica;
+inline constexpr struct point final : named_unit<"p", mag_ratio<1, 12> * pica> {} point;
+inline constexpr struct mil final : named_unit<"mil", mag_ratio<1, 1'000> * inch> {} mil;
+inline constexpr struct twip final : named_unit<"twip", mag_ratio<1, 20> * point> {} twip;
+inline constexpr struct mile final : named_unit<"mi", mag<1760> * yard> {} mile;
+inline constexpr struct league final : named_unit<"le", mag<3> * mile> {} league;
 
-inline constexpr struct nautical_mile : named_unit<"nmi", mag<1852> * si::metre> {} nautical_mile;
+inline constexpr struct nautical_mile final : named_unit<"nmi", mag<1852> * si::metre> {} nautical_mile;
 
 // speed
-inline constexpr struct knot : named_unit<"kn", nautical_mile / si::hour> {} knot;
+inline constexpr struct knot final : named_unit<"kn", nautical_mile / si::hour> {} knot;
 
 // force
 // https://en.wikipedia.org/wiki/Poundal
-inline constexpr struct poundal : named_unit<"pdl", pound * foot / square(si::second)> {} poundal;
+inline constexpr struct poundal final : named_unit<"pdl", pound * foot / square(si::second)> {} poundal;
 
 // https://en.wikipedia.org/wiki/Pound_(force)
-inline constexpr struct pound_force : named_unit<"lbf", pound * si::standard_gravity> {} pound_force;
+inline constexpr struct pound_force final : named_unit<"lbf", pound * si::standard_gravity> {} pound_force;
 
 // https://en.wikipedia.org/wiki/Kip_(unit),
 inline constexpr auto kip = si::kilo<pound_force>;
 
 // pressure
-inline constexpr struct psi : named_unit<"psi", pound_force / square(inch)> {} psi;
+inline constexpr struct psi final : named_unit<"psi", pound_force / square(inch)> {} psi;
 
 // power
 // https://en.wikipedia.org/wiki/Horsepower#Definitions
-inline constexpr struct mechanical_horsepower : named_unit<"hp(I)", mag<33'000> * foot * pound_force / si::minute> {} mechanical_horsepower;
+inline constexpr struct mechanical_horsepower final : named_unit<"hp(I)", mag<33'000> * foot * pound_force / si::minute> {} mechanical_horsepower;
 // clang-format on
 
 
diff --git a/src/systems/include/mp-units/systems/natural.h b/src/systems/include/mp-units/systems/natural.h
index 35f63339..b5a65b63 100644
--- a/src/systems/include/mp-units/systems/natural.h
+++ b/src/systems/include/mp-units/systems/natural.h
@@ -38,7 +38,7 @@ namespace mp_units::natural {
 
 // clang-format off
 // units
-inline constexpr struct electronvolt : named_unit<"eV"> {} electronvolt;
+inline constexpr struct electronvolt final : named_unit<"eV"> {} electronvolt;
 inline constexpr auto gigaelectronvolt = si::giga<electronvolt>;
 
 // system references
diff --git a/src/systems/include/mp-units/systems/si/constants.h b/src/systems/include/mp-units/systems/si/constants.h
index 6f4afef6..a43c871c 100644
--- a/src/systems/include/mp-units/systems/si/constants.h
+++ b/src/systems/include/mp-units/systems/si/constants.h
@@ -35,28 +35,28 @@ namespace mp_units::si {
 namespace si2019 {
 
 // clang-format off
-inline constexpr struct hyperfine_structure_transition_frequency_of_cs :
+inline constexpr struct hyperfine_structure_transition_frequency_of_cs final :
   named_unit<symbol_text{u8"Δν_Cs", "dv_Cs"}, mag<9'192'631'770> * hertz> {} hyperfine_structure_transition_frequency_of_cs;
-inline constexpr struct speed_of_light_in_vacuum :
+inline constexpr struct speed_of_light_in_vacuum final :
   named_unit<"c", mag<299'792'458> * metre / second> {} speed_of_light_in_vacuum;
-inline constexpr struct planck_constant :
+inline constexpr struct planck_constant final :
   named_unit<"h", mag_ratio<662'607'015, 100'000'000> * mag_power<10, -34> * joule * second> {} planck_constant;
-inline constexpr struct elementary_charge :
+inline constexpr struct elementary_charge final :
   named_unit<"e", mag_ratio<1'602'176'634, 1'000'000'000> * mag_power<10, -19> * coulomb> {} elementary_charge;
-inline constexpr struct boltzmann_constant :
+inline constexpr struct boltzmann_constant final :
   named_unit<"k", mag_ratio<1'380'649, 1'000'000> * mag_power<10, -23> * joule / kelvin> {} boltzmann_constant;
-inline constexpr struct avogadro_constant :
+inline constexpr struct avogadro_constant final :
   named_unit<"N_A", mag_ratio<602'214'076, 100'000'000> * mag_power<10, 23> / mole> {} avogadro_constant;
-inline constexpr struct luminous_efficacy :
+inline constexpr struct luminous_efficacy final :
   named_unit<"K_cd", mag<683> * lumen / watt> {} luminous_efficacy;
 // clang-format on
 
 }  // namespace si2019
 
 // clang-format off
-inline constexpr struct standard_gravity :
+inline constexpr struct standard_gravity final :
   named_unit<symbol_text{u8"g₀", "g_0"}, mag_ratio<980'665, 100'000> * metre / square(second)> {} standard_gravity;
-inline constexpr struct magnetic_constant :
+inline constexpr struct magnetic_constant final :
   named_unit<symbol_text{u8"μ₀", "u_0"}, mag<4> * mag_pi * mag_power<10, -7> * henry / metre> {} magnetic_constant;
 // clang-format on
 
diff --git a/src/systems/include/mp-units/systems/si/prefixes.h b/src/systems/include/mp-units/systems/si/prefixes.h
index 0aac147b..3ee39e13 100644
--- a/src/systems/include/mp-units/systems/si/prefixes.h
+++ b/src/systems/include/mp-units/systems/si/prefixes.h
@@ -31,30 +31,30 @@
 namespace mp_units::si {
 
 // clang-format off
-template<PrefixableUnit U> struct quecto_ : prefixed_unit<"q", mag_power<10, -30>, U{}> {};
-template<PrefixableUnit U> struct ronto_ : prefixed_unit<"r", mag_power<10, -27>, U{}> {};
-template<PrefixableUnit U> struct yocto_ : prefixed_unit<"y", mag_power<10, -24>, U{}> {};
-template<PrefixableUnit U> struct zepto_ : prefixed_unit<"z", mag_power<10, -21>, U{}> {};
-template<PrefixableUnit U> struct atto_  : prefixed_unit<"a", mag_power<10, -18>, U{}> {};
-template<PrefixableUnit U> struct femto_ : prefixed_unit<"f", mag_power<10, -15>, U{}> {};
-template<PrefixableUnit U> struct pico_  : prefixed_unit<"p", mag_power<10, -12>, U{}> {};
-template<PrefixableUnit U> struct nano_  : prefixed_unit<"n", mag_power<10, -9>, U{}> {};
-template<PrefixableUnit U> struct micro_ : prefixed_unit<symbol_text{u8"µ", "u"}, mag_power<10, -6>, U{}> {};
-template<PrefixableUnit U> struct milli_ : prefixed_unit<"m", mag_power<10, -3>, U{}> {};
-template<PrefixableUnit U> struct centi_ : prefixed_unit<"c", mag_power<10, -2>, U{}> {};
-template<PrefixableUnit U> struct deci_  : prefixed_unit<"d", mag_power<10, -1>, U{}> {};
-template<PrefixableUnit U> struct deca_  : prefixed_unit<"da", mag_power<10, 1>, U{}> {};
-template<PrefixableUnit U> struct hecto_ : prefixed_unit<"h", mag_power<10, 2>, U{}> {};
-template<PrefixableUnit U> struct kilo_  : prefixed_unit<"k", mag_power<10, 3>, U{}> {};
-template<PrefixableUnit U> struct mega_  : prefixed_unit<"M", mag_power<10, 6>, U{}> {};
-template<PrefixableUnit U> struct giga_  : prefixed_unit<"G", mag_power<10, 9>, U{}> {};
-template<PrefixableUnit U> struct tera_  : prefixed_unit<"T", mag_power<10, 12>, U{}> {};
-template<PrefixableUnit U> struct peta_  : prefixed_unit<"P", mag_power<10, 15>, U{}> {};
-template<PrefixableUnit U> struct exa_   : prefixed_unit<"E", mag_power<10, 18>, U{}> {};
-template<PrefixableUnit U> struct zetta_ : prefixed_unit<"Z", mag_power<10, 21>, U{}> {};
-template<PrefixableUnit U> struct yotta_ : prefixed_unit<"Y", mag_power<10, 24>, U{}> {};
-template<PrefixableUnit U> struct ronna_ : prefixed_unit<"R", mag_power<10, 27>, U{}> {};
-template<PrefixableUnit U> struct quetta_ : prefixed_unit<"Q", mag_power<10, 30>, U{}> {};
+template<PrefixableUnit U> struct quecto_ final : prefixed_unit<"q", mag_power<10, -30>, U{}> {};
+template<PrefixableUnit U> struct ronto_  final : prefixed_unit<"r", mag_power<10, -27>, U{}> {};
+template<PrefixableUnit U> struct yocto_  final : prefixed_unit<"y", mag_power<10, -24>, U{}> {};
+template<PrefixableUnit U> struct zepto_  final : prefixed_unit<"z", mag_power<10, -21>, U{}> {};
+template<PrefixableUnit U> struct atto_   final : prefixed_unit<"a", mag_power<10, -18>, U{}> {};
+template<PrefixableUnit U> struct femto_  final : prefixed_unit<"f", mag_power<10, -15>, U{}> {};
+template<PrefixableUnit U> struct pico_   final : prefixed_unit<"p", mag_power<10, -12>, U{}> {};
+template<PrefixableUnit U> struct nano_   final : prefixed_unit<"n", mag_power<10, -9>, U{}> {};
+template<PrefixableUnit U> struct micro_  final : prefixed_unit<symbol_text{u8"µ", "u"}, mag_power<10, -6>, U{}> {};
+template<PrefixableUnit U> struct milli_  final : prefixed_unit<"m", mag_power<10, -3>, U{}> {};
+template<PrefixableUnit U> struct centi_  final : prefixed_unit<"c", mag_power<10, -2>, U{}> {};
+template<PrefixableUnit U> struct deci_   final : prefixed_unit<"d", mag_power<10, -1>, U{}> {};
+template<PrefixableUnit U> struct deca_   final : prefixed_unit<"da", mag_power<10, 1>, U{}> {};
+template<PrefixableUnit U> struct hecto_  final : prefixed_unit<"h", mag_power<10, 2>, U{}> {};
+template<PrefixableUnit U> struct kilo_   final : prefixed_unit<"k", mag_power<10, 3>, U{}> {};
+template<PrefixableUnit U> struct mega_   final : prefixed_unit<"M", mag_power<10, 6>, U{}> {};
+template<PrefixableUnit U> struct giga_   final : prefixed_unit<"G", mag_power<10, 9>, U{}> {};
+template<PrefixableUnit U> struct tera_   final : prefixed_unit<"T", mag_power<10, 12>, U{}> {};
+template<PrefixableUnit U> struct peta_   final : prefixed_unit<"P", mag_power<10, 15>, U{}> {};
+template<PrefixableUnit U> struct exa_    final : prefixed_unit<"E", mag_power<10, 18>, U{}> {};
+template<PrefixableUnit U> struct zetta_  final : prefixed_unit<"Z", mag_power<10, 21>, U{}> {};
+template<PrefixableUnit U> struct yotta_  final : prefixed_unit<"Y", mag_power<10, 24>, U{}> {};
+template<PrefixableUnit U> struct ronna_  final : prefixed_unit<"R", mag_power<10, 27>, U{}> {};
+template<PrefixableUnit U> struct quetta_ final : prefixed_unit<"Q", mag_power<10, 30>, U{}> {};
 
 MP_UNITS_EXPORT_BEGIN
 
diff --git a/src/systems/include/mp-units/systems/si/units.h b/src/systems/include/mp-units/systems/si/units.h
index 72b16ba3..e13940a0 100644
--- a/src/systems/include/mp-units/systems/si/units.h
+++ b/src/systems/include/mp-units/systems/si/units.h
@@ -38,55 +38,55 @@ namespace si {
 
 // clang-format off
 // base units
-inline constexpr struct second : named_unit<"s", kind_of<isq::time>> {} second;
-inline constexpr struct metre : named_unit<"m", kind_of<isq::length>> {} metre;
-inline constexpr struct gram : named_unit<"g", kind_of<isq::mass>> {} gram;
+inline constexpr struct second final : named_unit<"s", kind_of<isq::time>> {} second;
+inline constexpr struct metre final : named_unit<"m", kind_of<isq::length>> {} metre;
+inline constexpr struct gram final : named_unit<"g", kind_of<isq::mass>> {} gram;
 inline constexpr auto kilogram = kilo<gram>;
-inline constexpr struct ampere : named_unit<"A", kind_of<isq::electric_current>> {} ampere;
+inline constexpr struct ampere final : named_unit<"A", kind_of<isq::electric_current>> {} ampere;
 
 inline constexpr struct absolute_zero : absolute_point_origin<absolute_zero, isq::thermodynamic_temperature> {} absolute_zero;
 inline constexpr struct zeroth_kelvin : decltype(absolute_zero) {} zeroth_kelvin;
-inline constexpr struct kelvin : named_unit<"K", kind_of<isq::thermodynamic_temperature>, zeroth_kelvin> {} kelvin;
+inline constexpr struct kelvin final : named_unit<"K", kind_of<isq::thermodynamic_temperature>, zeroth_kelvin> {} kelvin;
 
-inline constexpr struct mole : named_unit<"mol", kind_of<isq::amount_of_substance>> {} mole;
-inline constexpr struct candela : named_unit<"cd", kind_of<isq::luminous_intensity>> {} candela;
+inline constexpr struct mole final : named_unit<"mol", kind_of<isq::amount_of_substance>> {} mole;
+inline constexpr struct candela final : named_unit<"cd", kind_of<isq::luminous_intensity>> {} candela;
 
 // derived named units
-inline constexpr struct radian : named_unit<"rad", metre / metre, kind_of<isq::angular_measure>> {} radian;
-inline constexpr struct steradian : named_unit<"sr", square(metre) / square(metre), kind_of<isq::solid_angular_measure>> {} steradian;
-inline constexpr struct hertz : named_unit<"Hz", one / second, kind_of<isq::frequency>> {} hertz;
-inline constexpr struct newton : named_unit<"N", kilogram * metre / square(second)> {} newton;
+inline constexpr struct radian final : named_unit<"rad", metre / metre, kind_of<isq::angular_measure>> {} radian;
+inline constexpr struct steradian final : named_unit<"sr", square(metre) / square(metre), kind_of<isq::solid_angular_measure>> {} steradian;
+inline constexpr struct hertz final : named_unit<"Hz", one / second, kind_of<isq::frequency>> {} hertz;
+inline constexpr struct newton final : named_unit<"N", kilogram * metre / square(second)> {} newton;
 #ifdef pascal
 #pragma push_macro("pascal")
 #undef pascal
 #define MP_UNITS_REDEFINE_PASCAL
 #endif
-inline constexpr struct pascal : named_unit<"Pa", newton / square(metre)> {} pascal;
+inline constexpr struct pascal final : named_unit<"Pa", newton / square(metre)> {} pascal;
 #ifdef MP_UNITS_REDEFINE_PASCAL
 #pragma pop_macro("pascal")
 #undef MP_UNITS_REDEFINE_PASCAL
 #endif
-inline constexpr struct joule : named_unit<"J", newton * metre> {} joule;
-inline constexpr struct watt : named_unit<"W", joule / second> {} watt;
-inline constexpr struct coulomb : named_unit<"C", ampere * second> {} coulomb;
-inline constexpr struct volt : named_unit<"V", watt / ampere> {} volt;
-inline constexpr struct farad : named_unit<"F", coulomb / volt> {} farad;
-inline constexpr struct ohm : named_unit<symbol_text{u8"Ω", "ohm"}, volt / ampere> {} ohm;
-inline constexpr struct siemens : named_unit<"S", one / ohm> {} siemens;
-inline constexpr struct weber : named_unit<"Wb", volt * second> {} weber;
-inline constexpr struct tesla : named_unit<"T", weber / square(metre)> {} tesla;
-inline constexpr struct henry : named_unit<"H", weber / ampere> {} henry;
+inline constexpr struct joule final : named_unit<"J", newton * metre> {} joule;
+inline constexpr struct watt final : named_unit<"W", joule / second> {} watt;
+inline constexpr struct coulomb final : named_unit<"C", ampere * second> {} coulomb;
+inline constexpr struct volt final : named_unit<"V", watt / ampere> {} volt;
+inline constexpr struct farad final : named_unit<"F", coulomb / volt> {} farad;
+inline constexpr struct ohm final : named_unit<symbol_text{u8"Ω", "ohm"}, volt / ampere> {} ohm;
+inline constexpr struct siemens final : named_unit<"S", one / ohm> {} siemens;
+inline constexpr struct weber final : named_unit<"Wb", volt * second> {} weber;
+inline constexpr struct tesla final : named_unit<"T", weber / square(metre)> {} tesla;
+inline constexpr struct henry final : named_unit<"H", weber / ampere> {} henry;
 
 inline constexpr struct ice_point : relative_point_origin<quantity_point{273'150 * milli<kelvin>}> {} ice_point;
 inline constexpr struct zeroth_degree_Celsius : decltype(ice_point) {} zeroth_degree_Celsius;
-inline constexpr struct degree_Celsius : named_unit<symbol_text{u8"°C", "`C"}, kelvin, zeroth_degree_Celsius> {} degree_Celsius;
+inline constexpr struct degree_Celsius final : named_unit<symbol_text{u8"°C", "`C"}, kelvin, zeroth_degree_Celsius> {} degree_Celsius;
 
-inline constexpr struct lumen : named_unit<"lm", candela * steradian> {} lumen;
-inline constexpr struct lux : named_unit<"lx", lumen / square(metre)> {} lux;
-inline constexpr struct becquerel : named_unit<"Bq", one / second, kind_of<isq::activity>> {} becquerel;
-inline constexpr struct gray : named_unit<"Gy", joule / kilogram, kind_of<isq::absorbed_dose>> {} gray;
-inline constexpr struct sievert : named_unit<"Sv", joule / kilogram, kind_of<isq::dose_equivalent>> {} sievert;
-inline constexpr struct katal : named_unit<"kat", mole / second> {} katal;
+inline constexpr struct lumen final : named_unit<"lm", candela * steradian> {} lumen;
+inline constexpr struct lux final : named_unit<"lx", lumen / square(metre)> {} lux;
+inline constexpr struct becquerel final : named_unit<"Bq", one / second, kind_of<isq::activity>> {} becquerel;
+inline constexpr struct gray final : named_unit<"Gy", joule / kilogram, kind_of<isq::absorbed_dose>> {} gray;
+inline constexpr struct sievert final : named_unit<"Sv", joule / kilogram, kind_of<isq::dose_equivalent>> {} sievert;
+inline constexpr struct katal final : named_unit<"kat", mole / second> {} katal;
 // clang-format on
 
 }  // namespace si
@@ -95,20 +95,20 @@ namespace non_si {
 
 // clang-format off
 // non-SI units accepted for use with the SI
-inline constexpr struct minute : named_unit<"min", mag<60> * si::second> {} minute;
-inline constexpr struct hour : named_unit<"h", mag<60> * minute> {} hour;
-inline constexpr struct day : named_unit<"d", mag<24> * hour> {} day;
-inline constexpr struct astronomical_unit : named_unit<"au", mag<149'597'870'700> * si::metre> {} astronomical_unit;
-inline constexpr struct degree : named_unit<symbol_text{u8"°", "deg"}, mag_pi / mag<180> * si::radian> {} degree;
-inline constexpr struct arcminute : named_unit<symbol_text{u8"′", "'"}, mag_ratio<1, 60> * degree> {} arcminute;
-inline constexpr struct arcsecond : named_unit<symbol_text{u8"″", "''"}, mag_ratio<1, 60> * arcminute> {} arcsecond;
-inline constexpr struct are : named_unit<"a", square(si::deca<si::metre>)> {} are;
+inline constexpr struct minute final : named_unit<"min", mag<60> * si::second> {} minute;
+inline constexpr struct hour final : named_unit<"h", mag<60> * minute> {} hour;
+inline constexpr struct day final : named_unit<"d", mag<24> * hour> {} day;
+inline constexpr struct astronomical_unit final : named_unit<"au", mag<149'597'870'700> * si::metre> {} astronomical_unit;
+inline constexpr struct degree final : named_unit<symbol_text{u8"°", "deg"}, mag_pi / mag<180> * si::radian> {} degree;
+inline constexpr struct arcminute final : named_unit<symbol_text{u8"′", "'"}, mag_ratio<1, 60> * degree> {} arcminute;
+inline constexpr struct arcsecond final : named_unit<symbol_text{u8"″", "''"}, mag_ratio<1, 60> * arcminute> {} arcsecond;
+inline constexpr struct are final : named_unit<"a", square(si::deca<si::metre>)> {} are;
 inline constexpr auto hectare = si::hecto<are>;
-inline constexpr struct litre : named_unit<"l", cubic(si::deci<si::metre>)> {} litre;
-inline constexpr struct tonne : named_unit<"t", mag<1000> * si::kilogram> {} tonne;
-inline constexpr struct dalton : named_unit<"Da", mag_ratio<16'605'390'666'050, 10'000'000'000'000> * mag_power<10, -27> * si::kilogram> {} dalton;
+inline constexpr struct litre final : named_unit<"l", cubic(si::deci<si::metre>)> {} litre;
+inline constexpr struct tonne final : named_unit<"t", mag<1000> * si::kilogram> {} tonne;
+inline constexpr struct dalton final : named_unit<"Da", mag_ratio<16'605'390'666'050, 10'000'000'000'000> * mag_power<10, -27> * si::kilogram> {} dalton;
 // TODO A different value is provided in the SI Brochure and different in the ISO 80000
-inline constexpr struct electronvolt : named_unit<"eV", mag_ratio<1'602'176'634, 1'000'000'000> * mag_power<10, -19> * si::joule> {} electronvolt;
+inline constexpr struct electronvolt final : named_unit<"eV", mag_ratio<1'602'176'634, 1'000'000'000> * mag_power<10, -19> * si::joule> {} electronvolt;
 // TODO the below are logarithmic units - how to support those?
 // neper
 // bel
diff --git a/src/systems/include/mp-units/systems/typographic.h b/src/systems/include/mp-units/systems/typographic.h
index 67bdf53c..f368d350 100644
--- a/src/systems/include/mp-units/systems/typographic.h
+++ b/src/systems/include/mp-units/systems/typographic.h
@@ -36,11 +36,11 @@ namespace mp_units::typographic {
 
 // clang-format off
 // https://en.wikipedia.org/wiki/Point_(typography)
-inline constexpr struct pica_us : named_unit<"pica(us)", mag_ratio<166'044, 1'000'000> * international::inch> {} pica_us;
-inline constexpr struct point_us : named_unit<"point(us)", mag_ratio<1, 12> * pica_us> {} point_us;
+inline constexpr struct pica_us final : named_unit<"pica(us)", mag_ratio<166'044, 1'000'000> * international::inch> {} pica_us;
+inline constexpr struct point_us final : named_unit<"point(us)", mag_ratio<1, 12> * pica_us> {} point_us;
 
-inline constexpr struct point_dtp : named_unit<"point(dtp)", mag_ratio<1, 72> * international::inch> {} point_dtp;
-inline constexpr struct pica_dtp : named_unit<"pica(dtp)", mag<12> * point_dtp> {} pica_dtp;
+inline constexpr struct point_dtp final : named_unit<"point(dtp)", mag_ratio<1, 72> * international::inch> {} point_dtp;
+inline constexpr struct pica_dtp final : named_unit<"pica(dtp)", mag<12> * point_dtp> {} pica_dtp;
 // clang-format on
 
 }  // namespace mp_units::typographic
diff --git a/src/systems/include/mp-units/systems/usc.h b/src/systems/include/mp-units/systems/usc.h
index 87c7ace5..2b3ff049 100644
--- a/src/systems/include/mp-units/systems/usc.h
+++ b/src/systems/include/mp-units/systems/usc.h
@@ -41,12 +41,12 @@ using namespace international;
 
 // https://en.wikipedia.org/wiki/United_States_customary_units#Length
 // nautical
-inline constexpr struct fathom : named_unit<"ftm(us)", mag<2> * yard> {} fathom;
-inline constexpr struct cable : named_unit<"cb(us)", mag<120> * fathom> {} cable;
+inline constexpr struct fathom final : named_unit<"ftm(us)", mag<2> * yard> {} fathom;
+inline constexpr struct cable final : named_unit<"cb(us)", mag<120> * fathom> {} cable;
 
 // survey
-struct us_survey_foot : named_unit<"ft(us)", mag_ratio<1'200, 3'937> * si::metre> {};
-struct us_survey_mile : named_unit<"mi(us)", mag<5280> * us_survey_foot{}> {};
+struct us_survey_foot final : named_unit<"ft(us)", mag_ratio<1'200, 3'937> * si::metre> {};
+struct us_survey_mile final : named_unit<"mi(us)", mag<5280> * us_survey_foot{}> {};
 
 [[deprecated("In accordance with NIST SP 811, as of January 1, 2023, the use of the U.S. survey foot and U.S. survey mile is deprecated.")]]
 inline constexpr us_survey_foot us_survey_foot;
@@ -54,72 +54,72 @@ inline constexpr us_survey_foot us_survey_foot;
 [[deprecated("In accordance with NIST SP 811, as of January 1, 2023, the use of the U.S. survey foot and U.S. survey mile is deprecated.")]]
 inline constexpr us_survey_mile us_survey_mile;
 
-inline constexpr struct link : named_unit<"li", mag_ratio<33, 50> * foot> {} link;
-inline constexpr struct rod : named_unit<"rd", mag<25> * link> {} rod;
-inline constexpr struct chain : named_unit<"ch", mag<4> * rod> {} chain;
-inline constexpr struct furlong : named_unit<"fur", mag<10> * chain> {} furlong;
+inline constexpr struct link final : named_unit<"li", mag_ratio<33, 50> * foot> {} link;
+inline constexpr struct rod final : named_unit<"rd", mag<25> * link> {} rod;
+inline constexpr struct chain final : named_unit<"ch", mag<4> * rod> {} chain;
+inline constexpr struct furlong final : named_unit<"fur", mag<10> * chain> {} furlong;
 // clang-format on
 
 namespace survey1893 {
 
 // clang-format off
-inline constexpr struct us_survey_foot : named_unit<"ft(us)", mag_ratio<1'200, 3'937> * si::metre> {} us_survey_foot;
-inline constexpr struct link : named_unit<"li", mag_ratio<33, 50> * us_survey_foot> {} link;
-inline constexpr struct rod : named_unit<"rd", mag<25> * link> {} rod;
-inline constexpr struct chain : named_unit<"ch", mag<4> * rod> {} chain;
-inline constexpr struct furlong : named_unit<"fur", mag<10> * chain> {} furlong;
-inline constexpr struct us_survey_mile : named_unit<"mi(us)", mag<8> * furlong> {} us_survey_mile;
-inline constexpr struct league : named_unit<"lea", mag<3> * us_survey_mile> {} league;
+inline constexpr struct us_survey_foot final : named_unit<"ft(us)", mag_ratio<1'200, 3'937> * si::metre> {} us_survey_foot;
+inline constexpr struct link final : named_unit<"li", mag_ratio<33, 50> * us_survey_foot> {} link;
+inline constexpr struct rod final : named_unit<"rd", mag<25> * link> {} rod;
+inline constexpr struct chain final : named_unit<"ch", mag<4> * rod> {} chain;
+inline constexpr struct furlong final : named_unit<"fur", mag<10> * chain> {} furlong;
+inline constexpr struct us_survey_mile final : named_unit<"mi(us)", mag<8> * furlong> {} us_survey_mile;
+inline constexpr struct league final : named_unit<"lea", mag<3> * us_survey_mile> {} league;
 // clang-format on
 
 }  // namespace survey1893
 
 // clang-format off
 // https://en.wikipedia.org/wiki/United_States_customary_units#Area
-inline constexpr struct acre : named_unit<"acre", mag<10> * square(survey1893::chain)> {} acre;
-inline constexpr struct section : named_unit<"section", mag<640> * acre> {} section;
+inline constexpr struct acre final : named_unit<"acre", mag<10> * square(survey1893::chain)> {} acre;
+inline constexpr struct section final : named_unit<"section", mag<640> * acre> {} section;
 
 // https://en.wikipedia.org/wiki/United_States_customary_units#Fluid_volume
-inline constexpr struct gallon : named_unit<"gal", mag<231> * cubic(inch)> {} gallon;
-inline constexpr struct pottle : named_unit<"pot", mag_ratio<1, 2> * gallon> {} pottle;
-inline constexpr struct quart : named_unit<"qt", mag_ratio<1, 2> * pottle> {} quart;
-inline constexpr struct pint : named_unit<"pt", mag_ratio<1, 2> * quart> {} pint;
-inline constexpr struct cup : named_unit<"c", mag_ratio<1, 2> * pint> {} cup;
-inline constexpr struct gill : named_unit<"gi", mag_ratio<1, 2> * cup> {} gill;
-inline constexpr struct fluid_ounce : named_unit<"fl oz", mag_ratio<1, 4> * gill> {} fluid_ounce;
-inline constexpr struct tablespoon : named_unit<"tbsp", mag_ratio<1, 2> * fluid_ounce> {} tablespoon;
-inline constexpr struct shot : named_unit<"jig", mag<3> * tablespoon> {} shot;
-inline constexpr struct teaspoon : named_unit<"tsp", mag_ratio<1, 3> * tablespoon> {} teaspoon;
-inline constexpr struct minim : named_unit<"min", mag_ratio<1, 80> * teaspoon> {} minim;
-inline constexpr struct fluid_dram : named_unit<"fl dr", mag<60> * minim> {} fluid_dram;
-inline constexpr struct barrel : named_unit<"bbl", mag_ratio<315, 10> * gallon> {} barrel;
-inline constexpr struct oil_barrel : named_unit<"bbl", mag_ratio<4, 3> * barrel> {} oil_barrel;
-inline constexpr struct hogshead : named_unit<"hogshead", mag<63> * gallon> {} hogshead;
+inline constexpr struct gallon final : named_unit<"gal", mag<231> * cubic(inch)> {} gallon;
+inline constexpr struct pottle final : named_unit<"pot", mag_ratio<1, 2> * gallon> {} pottle;
+inline constexpr struct quart final : named_unit<"qt", mag_ratio<1, 2> * pottle> {} quart;
+inline constexpr struct pint final : named_unit<"pt", mag_ratio<1, 2> * quart> {} pint;
+inline constexpr struct cup final : named_unit<"c", mag_ratio<1, 2> * pint> {} cup;
+inline constexpr struct gill final : named_unit<"gi", mag_ratio<1, 2> * cup> {} gill;
+inline constexpr struct fluid_ounce final : named_unit<"fl oz", mag_ratio<1, 4> * gill> {} fluid_ounce;
+inline constexpr struct tablespoon final : named_unit<"tbsp", mag_ratio<1, 2> * fluid_ounce> {} tablespoon;
+inline constexpr struct shot final : named_unit<"jig", mag<3> * tablespoon> {} shot;
+inline constexpr struct teaspoon final : named_unit<"tsp", mag_ratio<1, 3> * tablespoon> {} teaspoon;
+inline constexpr struct minim final : named_unit<"min", mag_ratio<1, 80> * teaspoon> {} minim;
+inline constexpr struct fluid_dram final : named_unit<"fl dr", mag<60> * minim> {} fluid_dram;
+inline constexpr struct barrel final : named_unit<"bbl", mag_ratio<315, 10> * gallon> {} barrel;
+inline constexpr struct oil_barrel final : named_unit<"bbl", mag_ratio<4, 3> * barrel> {} oil_barrel;
+inline constexpr struct hogshead final : named_unit<"hogshead", mag<63> * gallon> {} hogshead;
 
 // https://en.wikipedia.org/wiki/United_States_customary_units#Dry_volume
-inline constexpr struct dry_barrel : named_unit<"bbl", mag<7056> * cubic(inch)> {} dry_barrel;
-inline constexpr struct bushel : named_unit<"bu", mag_ratio<3'523'907'016'688, 100'000'000'000> * si::litre> {} bushel;
-inline constexpr struct peck : named_unit<"pk", mag_ratio<1, 4> * bushel> {} peck;
-inline constexpr struct dry_gallon : named_unit<"gal", mag_ratio<1, 2> * peck> {} dry_gallon;
-inline constexpr struct dry_quart : named_unit<"qt", mag_ratio<1, 4> * dry_gallon> {} dry_quart;
-inline constexpr struct dry_pint : named_unit<"pt", mag_ratio<1, 2> * dry_quart> {} dry_pint;
+inline constexpr struct dry_barrel final : named_unit<"bbl", mag<7056> * cubic(inch)> {} dry_barrel;
+inline constexpr struct bushel final : named_unit<"bu", mag_ratio<3'523'907'016'688, 100'000'000'000> * si::litre> {} bushel;
+inline constexpr struct peck final : named_unit<"pk", mag_ratio<1, 4> * bushel> {} peck;
+inline constexpr struct dry_gallon final : named_unit<"gal", mag_ratio<1, 2> * peck> {} dry_gallon;
+inline constexpr struct dry_quart final : named_unit<"qt", mag_ratio<1, 4> * dry_gallon> {} dry_quart;
+inline constexpr struct dry_pint final : named_unit<"pt", mag_ratio<1, 2> * dry_quart> {} dry_pint;
 
 // https://en.wikipedia.org/wiki/United_States_customary_units#Mass_and_Weight
 // https://en.wikipedia.org/wiki/Avoirdupois_system#American_customary_system
-inline constexpr struct quarter : named_unit<"qr", mag<25> * pound> {} quarter;
-inline constexpr struct short_hundredweight : named_unit<"cwt", mag<100> * pound> {} short_hundredweight;
-inline constexpr struct ton : named_unit<"t", mag<2'000> * pound> {} ton;
+inline constexpr struct quarter final : named_unit<"qr", mag<25> * pound> {} quarter;
+inline constexpr struct short_hundredweight final : named_unit<"cwt", mag<100> * pound> {} short_hundredweight;
+inline constexpr struct ton final : named_unit<"t", mag<2'000> * pound> {} ton;
 inline constexpr auto short_ton = ton;
-inline constexpr struct pennyweight : named_unit<"dwt", mag<24> * grain> {} pennyweight;
-inline constexpr struct troy_once : named_unit<"oz t", mag<20> * pennyweight> {} troy_once;
-inline constexpr struct troy_pound : named_unit<"lb t", mag<12> * troy_once> {} troy_pound;
+inline constexpr struct pennyweight final : named_unit<"dwt", mag<24> * grain> {} pennyweight;
+inline constexpr struct troy_once final : named_unit<"oz t", mag<20> * pennyweight> {} troy_once;
+inline constexpr struct troy_pound final : named_unit<"lb t", mag<12> * troy_once> {} troy_pound;
 
 // https://en.wikipedia.org/wiki/Inch_of_mercury
-inline constexpr struct inch_of_mercury : named_unit<"inHg", mag_ratio<3'386'389, 1'000> * si::pascal> {} inch_of_mercury;
+inline constexpr struct inch_of_mercury final : named_unit<"inHg", mag_ratio<3'386'389, 1'000> * si::pascal> {} inch_of_mercury;
 
 // https://en.wikipedia.org/wiki/United_States_customary_units#Temperature
 inline constexpr struct zeroth_degree_Fahrenheit : relative_point_origin<quantity_point{-32 * (mag_ratio<5, 9> * si::degree_Celsius)}> {} zeroth_degree_Fahrenheit;
-inline constexpr struct degree_Fahrenheit : named_unit<symbol_text{u8"°F", "`F"}, mag_ratio<5, 9> * si::degree_Celsius, zeroth_degree_Fahrenheit> {} degree_Fahrenheit;
+inline constexpr struct degree_Fahrenheit final : named_unit<symbol_text{u8"°F", "`F"}, mag_ratio<5, 9> * si::degree_Celsius, zeroth_degree_Fahrenheit> {} degree_Fahrenheit;
 
 // clang-format on
 
diff --git a/test/runtime/truncation_test.cpp b/test/runtime/truncation_test.cpp
index eaef11b9..6b05b767 100644
--- a/test/runtime/truncation_test.cpp
+++ b/test/runtime/truncation_test.cpp
@@ -37,7 +37,7 @@ using namespace mp_units;
 using namespace mp_units::angular;
 using namespace mp_units::angular::unit_symbols;
 
-inline constexpr struct half_revolution : named_unit<"hrev", mag_pi * radian> {
+inline constexpr struct half_revolution final : named_unit<"hrev", mag_pi * radian> {
 } half_revolution;
 inline constexpr auto hrev = half_revolution;
 
diff --git a/test/static/dimension_test.cpp b/test/static/dimension_test.cpp
index 33f80262..a6f0fb36 100644
--- a/test/static/dimension_test.cpp
+++ b/test/static/dimension_test.cpp
@@ -40,7 +40,7 @@ inline constexpr struct my_length1_ : decltype(length) {} my_length1;
 inline constexpr struct my_length2_ : decltype(length) {} my_length2;
 
 QUANTITY_SPEC_(q_time, time);
-inline constexpr struct second_ : named_unit<"s", kind_of<q_time>> {} second;
+inline constexpr struct second_ final : named_unit<"s", kind_of<q_time>> {} second;
 
 inline constexpr auto frequency = inverse(time);
 inline constexpr auto action = inverse(time);
diff --git a/test/static/quantity_point_test.cpp b/test/static/quantity_point_test.cpp
index 24c5206d..33f9447a 100644
--- a/test/static/quantity_point_test.cpp
+++ b/test/static/quantity_point_test.cpp
@@ -120,7 +120,7 @@ static_assert(relative_po<absolute_po<isq::length> + isq::height(42 * m)>.quanti
 static_assert(relative_po<absolute_po<kind_of<isq::length>> + isq::height(42 * m)>.quantity_spec == isq::height);
 static_assert(relative_po<absolute_po<isq::height> + 42 * m>.quantity_spec == isq::height);
 
-inline constexpr struct my_kelvin : named_unit<"my_K", mag<10> * si::kelvin> {
+inline constexpr struct my_kelvin final : named_unit<"my_K", mag<10> * si::kelvin> {
 } my_kelvin;
 
 static_assert(default_point_origin(si::kelvin) == si::absolute_zero);
diff --git a/test/static/quantity_spec_test.cpp b/test/static/quantity_spec_test.cpp
index 7a62e5c4..a2dbd836 100644
--- a/test/static/quantity_spec_test.cpp
+++ b/test/static/quantity_spec_test.cpp
@@ -42,7 +42,7 @@ QUANTITY_SPEC_(length, dim_length);
 QUANTITY_SPEC_(mass, dim_mass);
 QUANTITY_SPEC_(time, dim_time);
 
-inline constexpr struct second_ : named_unit<"s", kind_of<time>> {} second;
+inline constexpr struct second_ final : named_unit<"s", kind_of<time>> {} second;
 
 QUANTITY_SPEC_(height, length);
 QUANTITY_SPEC_(width, length);
diff --git a/test/static/reference_test.cpp b/test/static/reference_test.cpp
index 58e2611d..a3e26ea9 100644
--- a/test/static/reference_test.cpp
+++ b/test/static/reference_test.cpp
@@ -60,16 +60,16 @@ QUANTITY_SPEC_(power, force* speed);
 QUANTITY_SPEC_(storage_capacity, dimensionless, is_kind);
 
 // base units
-inline constexpr struct second_ : named_unit<"s", kind_of<time>> {} second;
-inline constexpr struct metre_ : named_unit<"m", kind_of<length>> {} metre;
-inline constexpr struct gram_ : named_unit<"g", kind_of<mass>> {} gram;
-inline constexpr struct kilogram_ : decltype(si::kilo<gram>) {} kilogram;
+inline constexpr struct second_ final : named_unit<"s", kind_of<time>> {} second;
+inline constexpr struct metre_ final : named_unit<"m", kind_of<length>> {} metre;
+inline constexpr struct gram_ final : named_unit<"g", kind_of<mass>> {} gram;
+inline constexpr auto kilogram = si::kilo<gram>;
 
 namespace nu {
 // hypothetical natural system of units for c=1
 
-inline constexpr struct second_ : named_unit<"s"> {} second;
-inline constexpr struct minute_ : named_unit<"min", mag<60> * second> {} minute;
+inline constexpr struct second_ final : named_unit<"s"> {} second;
+inline constexpr struct minute_ final : named_unit<"min", mag<60> * second> {} minute;
 
 inline constexpr struct time : system_reference<time_{}, second> {} time;
 inline constexpr struct length : system_reference<length_{}, second> {} length;
@@ -78,19 +78,19 @@ inline constexpr struct speed : system_reference<speed_{}, second / second> {} s
 }
 
 // derived named units
-inline constexpr struct radian_ : named_unit<"rad", metre / metre, kind_of<angular_measure>> {} radian;
-inline constexpr struct steradian_ : named_unit<"sr", square(metre) / square(metre), kind_of<solid_angular_measure>> {} steradian;
-inline constexpr struct hertz_ : named_unit<"Hz", inverse(second), kind_of<frequency>> {} hertz;
-inline constexpr struct becquerel_ : named_unit<"Bq", inverse(second), kind_of<activity>> {} becquerel;
-inline constexpr struct newton_ : named_unit<"N", kilogram * metre / square(second)> {} newton;
-inline constexpr struct joule_ : named_unit<"J", newton * metre> {} joule;
-inline constexpr struct watt_ : named_unit<"W", joule / second> {} watt;
+inline constexpr struct radian_ final : named_unit<"rad", metre / metre, kind_of<angular_measure>> {} radian;
+inline constexpr struct steradian_ final : named_unit<"sr", square(metre) / square(metre), kind_of<solid_angular_measure>> {} steradian;
+inline constexpr struct hertz_ final : named_unit<"Hz", inverse(second), kind_of<frequency>> {} hertz;
+inline constexpr struct becquerel_ final : named_unit<"Bq", inverse(second), kind_of<activity>> {} becquerel;
+inline constexpr struct newton_ final : named_unit<"N", kilogram * metre / square(second)> {} newton;
+inline constexpr struct joule_ final : named_unit<"J", newton * metre> {} joule;
+inline constexpr struct watt_ final : named_unit<"W", joule / second> {} watt;
 
-inline constexpr struct minute_ : named_unit<"min", mag<60> * second> {} minute;
-inline constexpr struct hour_ : named_unit<"h", mag<60> * minute> {} hour;
-inline constexpr struct kilometre_ : decltype(si::kilo<metre>) {} kilometre;
+inline constexpr struct minute_ final : named_unit<"min", mag<60> * second> {} minute;
+inline constexpr struct hour_ final : named_unit<"h", mag<60> * minute> {} hour;
+inline constexpr auto kilometre = si::kilo<metre>;
 
-inline constexpr struct bit_ : named_unit<"bit", one, kind_of<storage_capacity>> {} bit;
+inline constexpr struct bit_ final : named_unit<"bit", one, kind_of<storage_capacity>> {} bit;
 // clang-format on
 
 
diff --git a/test/static/unit_test.cpp b/test/static/unit_test.cpp
index a89d21ea..bc39be81 100644
--- a/test/static/unit_test.cpp
+++ b/test/static/unit_test.cpp
@@ -48,39 +48,39 @@ QUANTITY_SPEC_(time, dim_time);
 QUANTITY_SPEC_(thermodynamic_temperature, dim_thermodynamic_temperature);
 
 // base units
-inline constexpr struct second_ : named_unit<"s", kind_of<time>> {} second;
-inline constexpr struct metre_ : named_unit<"m", kind_of<length>> {} metre;
-inline constexpr struct gram_ : named_unit<"g", kind_of<mass>> {} gram;
-inline constexpr struct kilogram_ : decltype(si::kilo<gram>) {} kilogram;
-inline constexpr struct kelvin_ : named_unit<"K", kind_of<thermodynamic_temperature>> {} kelvin;
+inline constexpr struct second_ final : named_unit<"s", kind_of<time>> {} second;
+inline constexpr struct metre_ final : named_unit<"m", kind_of<length>> {} metre;
+inline constexpr struct gram_ final : named_unit<"g", kind_of<mass>> {} gram;
+inline constexpr auto kilogram = si::kilo<gram>;
+inline constexpr struct kelvin_ final : named_unit<"K", kind_of<thermodynamic_temperature>> {} kelvin;
 
 // hypothetical natural units for c=1
-inline constexpr struct nu_second_ : named_unit<"s"> {} nu_second;
+inline constexpr struct nu_second_ final : named_unit<"s"> {} nu_second;
 
 // derived named units
-inline constexpr struct radian_ : named_unit<"rad", metre / metre> {} radian;
-inline constexpr struct steradian_ : named_unit<"sr", square(metre) / square(metre)> {} steradian;
-inline constexpr struct hertz_ : named_unit<"Hz", inverse(second)> {} hertz;
-inline constexpr struct becquerel_ : named_unit<"Bq", inverse(second)> {} becquerel;
-inline constexpr struct newton_ : named_unit<"N", kilogram * metre / square(second)> {} newton;
-inline constexpr struct pascal_ : named_unit<"Pa", newton / square(metre)> {} pascal;
-inline constexpr struct joule_ : named_unit<"J", newton * metre> {} joule;
-inline constexpr struct watt_ : named_unit<"W", joule / second> {} watt;
-inline constexpr struct degree_Celsius_ : named_unit<symbol_text{u8"°C", "`C"}, kelvin> {} degree_Celsius;
+inline constexpr struct radian_ final : named_unit<"rad", metre / metre> {} radian;
+inline constexpr struct steradian_ final : named_unit<"sr", square(metre) / square(metre)> {} steradian;
+inline constexpr struct hertz_ final : named_unit<"Hz", inverse(second)> {} hertz;
+inline constexpr struct becquerel_ final : named_unit<"Bq", inverse(second)> {} becquerel;
+inline constexpr struct newton_ final : named_unit<"N", kilogram * metre / square(second)> {} newton;
+inline constexpr struct pascal_ final : named_unit<"Pa", newton / square(metre)> {} pascal;
+inline constexpr struct joule_ final : named_unit<"J", newton * metre> {} joule;
+inline constexpr struct watt_ final : named_unit<"W", joule / second> {} watt;
+inline constexpr struct degree_Celsius_ final : named_unit<symbol_text{u8"°C", "`C"}, kelvin> {} degree_Celsius;
 
-inline constexpr struct minute_ : named_unit<"min", mag<60> * second> {} minute;
-inline constexpr struct hour_ : named_unit<"h", mag<60> * minute> {} hour;
-inline constexpr struct degree_ : named_unit<symbol_text{u8"°", "deg"}, mag_pi / mag<180> * radian> {} degree;
+inline constexpr struct minute_ final : named_unit<"min", mag<60> * second> {} minute;
+inline constexpr struct hour_ final : named_unit<"h", mag<60> * minute> {} hour;
+inline constexpr struct degree_ final : named_unit<symbol_text{u8"°", "deg"}, mag_pi / mag<180> * radian> {} degree;
 
-inline constexpr struct yard_ : named_unit<"yd", mag_ratio<9'144, 10'000> * metre> {} yard;
-inline constexpr struct mile_ : named_unit<"mi", mag<1760> * yard> {} mile;
+inline constexpr struct yard_ final : named_unit<"yd", mag_ratio<9'144, 10'000> * metre> {} yard;
+inline constexpr struct mile_ final : named_unit<"mi", mag<1760> * yard> {} mile;
 
-inline constexpr struct kilometre_ : decltype(si::kilo<metre>) {} kilometre;
-inline constexpr struct kilojoule_ : decltype(si::kilo<joule>) {} kilojoule;
+inline constexpr auto kilometre = si::kilo<metre>;
+inline constexpr auto kilojoule = si::kilo<joule>;
 
 // physical constant units
-inline constexpr struct standard_gravity_ : named_unit<symbol_text{u8"g₀", "g_0"}, mag_ratio<980'665, 100'000> * metre / square(second)> {} standard_gravity;
-inline constexpr struct speed_of_light_in_vacuum_ : named_unit<"c", mag<299'792'458> * metre / second> {} speed_of_light_in_vacuum;
+inline constexpr struct standard_gravity_ final : named_unit<symbol_text{u8"g₀", "g_0"}, mag_ratio<980'665, 100'000> * metre / square(second)> {} standard_gravity;
+inline constexpr struct speed_of_light_in_vacuum_ final : named_unit<"c", mag<299'792'458> * metre / second> {} speed_of_light_in_vacuum;
 
 // clang-format on
 
@@ -88,7 +88,7 @@ inline constexpr struct speed_of_light_in_vacuum_ : named_unit<"c", mag<299'792'
 static_assert(Unit<metre_>);
 static_assert(Unit<second_>);
 static_assert(Unit<nu_second_>);
-static_assert(Unit<kilogram_>);
+static_assert(Unit<decltype(kilogram)>);
 static_assert(Unit<hertz_>);
 static_assert(Unit<newton_>);
 static_assert(Unit<minute_>);
@@ -100,20 +100,20 @@ static_assert(Unit<decltype(second * second)>);
 static_assert(Unit<decltype(nu_second * nu_second)>);
 static_assert(Unit<decltype(metre / second)>);
 static_assert(Unit<decltype(nu_second / nu_second)>);
-static_assert(Unit<kilometre_>);
+static_assert(Unit<decltype(kilometre)>);
 
 static_assert(detail::NamedUnit<metre_>);
 static_assert(detail::NamedUnit<hertz_>);
 static_assert(detail::NamedUnit<newton_>);
 static_assert(detail::NamedUnit<minute_>);
 static_assert(detail::NamedUnit<radian_>);
-static_assert(!detail::NamedUnit<kilogram_>);
-static_assert(!detail::NamedUnit<kilojoule_>);
+static_assert(!detail::NamedUnit<decltype(kilogram)>);
+static_assert(!detail::NamedUnit<decltype(kilojoule)>);
 static_assert(!detail::NamedUnit<decltype(si::kilo<gram>)>);
 static_assert(!detail::NamedUnit<decltype(square(metre))>);
 static_assert(!detail::NamedUnit<decltype(cubic(metre))>);
 static_assert(!detail::NamedUnit<decltype(mag<60> * second)>);
-static_assert(!detail::NamedUnit<kilometre_>);
+static_assert(!detail::NamedUnit<decltype(kilometre)>);
 
 // named unit
 static_assert(is_of_type<metre, metre_>);
@@ -192,14 +192,14 @@ static_assert(standard_gravity != metre / square(second));  // magnitude is diff
 static_assert(standard_gravity.symbol == symbol_text{u8"g₀", "g_0"});
 
 // prefixed_unit
-static_assert(is_of_type<kilometre, kilometre_>);
+static_assert(is_of_type<kilometre, std::remove_const_t<decltype(si::kilo<metre>)>>);
 static_assert(is_of_type<get_canonical_unit(kilometre).reference_unit, metre_>);
 static_assert(get_canonical_unit(kilometre).mag == mag<1000>);
 static_assert(convertible(kilometre, metre));
 static_assert(kilometre != metre);
 static_assert(kilometre.symbol == "km");
 
-static_assert(is_of_type<kilojoule, kilojoule_>);
+static_assert(is_of_type<kilojoule, std::remove_const_t<decltype(si::kilo<joule>)>>);
 static_assert(is_of_type<get_canonical_unit(kilojoule).reference_unit,
                          derived_unit<gram_, power<metre_, 2>, per<power<second_, 2>>>>);
 static_assert(get_canonical_unit(kilojoule).mag == mag<1'000'000>);
@@ -210,8 +210,10 @@ static_assert(kilojoule.symbol == "kJ");
 static_assert(is_of_type<si::kilo<metre>, si::kilo_<metre_>>);
 static_assert(is_of_type<si::kilo<joule>, si::kilo_<joule_>>);
 
-static_assert(is_of_type<kilometre * metre, derived_unit<kilometre_, metre_>>);       // !!!
-static_assert(is_of_type<kilometre / metre, derived_unit<kilometre_, per<metre_>>>);  // !!!
+static_assert(
+  is_of_type<kilometre * metre, derived_unit<std::remove_const_t<decltype(si::kilo<metre>)>, metre_>>);  // !!!
+static_assert(
+  is_of_type<kilometre / metre, derived_unit<std::remove_const_t<decltype(si::kilo<metre>)>, per<metre_>>>);  // !!!
 
 
 // prefixes
@@ -252,7 +254,7 @@ static_assert(is_of_type<get_canonical_unit(m_2).reference_unit, metre_>);
 static_assert(get_canonical_unit(m_2).mag == mag<2>);
 
 constexpr auto km_2 = mag<2> * kilometre;
-static_assert(is_of_type<km_2, scaled_unit<mag<2>, kilometre_>>);
+static_assert(is_of_type<km_2, scaled_unit<mag<2>, std::remove_const_t<decltype(si::kilo<metre>)>>>);
 static_assert(is_of_type<get_canonical_unit(km_2).reference_unit, metre_>);
 static_assert(get_canonical_unit(km_2).mag == mag<2000>);
 
@@ -346,12 +348,12 @@ static_assert(is_of_type<get_canonical_unit(m_per_s).reference_unit, derived_uni
 static_assert(get_canonical_unit(m_per_s).mag == mag<1>);
 
 constexpr auto km_per_s = kilometre / second;
-static_assert(is_of_type<km_per_s, derived_unit<kilometre_, per<second_>>>);
+static_assert(is_of_type<km_per_s, derived_unit<std::remove_const_t<decltype(si::kilo<metre>)>, per<second_>>>);
 static_assert(is_of_type<get_canonical_unit(km_per_s).reference_unit, derived_unit<metre_, per<second_>>>);
 static_assert(get_canonical_unit(km_per_s).mag == mag<1000>);
 
 constexpr auto km_per_h = kilometre / hour;
-static_assert(is_of_type<km_per_h, derived_unit<kilometre_, per<hour_>>>);
+static_assert(is_of_type<km_per_h, derived_unit<std::remove_const_t<decltype(si::kilo<metre>)>, per<hour_>>>);
 static_assert(is_of_type<get_canonical_unit(km_per_h).reference_unit, derived_unit<metre_, per<second_>>>);
 static_assert(get_canonical_unit(km_per_h).mag == mag_ratio<1000, 3600>);
 
@@ -373,17 +375,20 @@ static_assert(is_of_type<get_canonical_unit(standard_gravity / speed_of_light_in
 
 // operations commutativity
 constexpr auto u1 = mag<1000> * kilometre / hour;
-static_assert(is_of_type<u1, scaled_unit<mag<1000>, derived_unit<kilometre_, per<hour_>>>>);
+static_assert(
+  is_of_type<u1, scaled_unit<mag<1000>, derived_unit<std::remove_const_t<decltype(si::kilo<metre>)>, per<hour_>>>>);
 static_assert(is_of_type<get_canonical_unit(u1).reference_unit, derived_unit<metre_, per<second_>>>);
 static_assert(get_canonical_unit(u1).mag == mag_ratio<1'000'000, 3'600>);
 
 constexpr auto u2 = mag<1000> * (kilometre / hour);
-static_assert(is_of_type<u2, scaled_unit<mag<1000>, derived_unit<kilometre_, per<hour_>>>>);
+static_assert(
+  is_of_type<u2, scaled_unit<mag<1000>, derived_unit<std::remove_const_t<decltype(si::kilo<metre>)>, per<hour_>>>>);
 static_assert(is_of_type<get_canonical_unit(u2).reference_unit, derived_unit<metre_, per<second_>>>);
 static_assert(get_canonical_unit(u2).mag == mag_ratio<1'000'000, 3'600>);
 
 constexpr auto u3 = one / hour * (mag<1000> * kilometre);
-static_assert(is_of_type<u3, scaled_unit<mag<1000>, derived_unit<kilometre_, per<hour_>>>>);
+static_assert(
+  is_of_type<u3, scaled_unit<mag<1000>, derived_unit<std::remove_const_t<decltype(si::kilo<metre>)>, per<hour_>>>>);
 static_assert(is_of_type<get_canonical_unit(u3).reference_unit, derived_unit<metre_, per<second_>>>);
 static_assert(get_canonical_unit(u3).mag == mag_ratio<1'000'000, 3'600>);
 
@@ -499,9 +504,10 @@ static_assert(is_of_type<pow<1, 3>(metre* metre* metre), metre_>);
 static_assert(is_of_type<pow<1, 3>(metre* metre), derived_unit<power<metre_, 2, 3>>>);
 static_assert(is_of_type<pow<1, 2>(metre / second), derived_unit<power<metre_, 1, 2>, per<power<second_, 1, 2>>>>);
 static_assert(is_of_type<pow<1, 2>(metre / (second * second)), derived_unit<power<metre_, 1, 2>, per<second_>>>);
-static_assert(is_of_type<kilometre * kilometre, derived_unit<power<kilometre_, 2>>>);
+static_assert(
+  is_of_type<kilometre * kilometre, derived_unit<power<std::remove_const_t<decltype(si::kilo<metre>)>, 2>>>);
 
-static_assert(is_of_type<pow<2>(kilometre), derived_unit<power<kilometre_, 2>>>);
+static_assert(is_of_type<pow<2>(kilometre), derived_unit<power<std::remove_const_t<decltype(si::kilo<metre>)>, 2>>>);
 static_assert(is_of_type<pow<2>(si::kilo<metre>), derived_unit<power<si::kilo_<metre_>, 2>>>);
 static_assert(is_of_type<pow<2>(hour), derived_unit<power<hour_, 2>>>);
 static_assert(
@@ -509,11 +515,11 @@ static_assert(
 
 // common_unit
 static_assert(is_of_type<common_unit(gram, gram), gram_>);
-static_assert(is_of_type<common_unit(kilogram, kilogram), kilogram_>);
-static_assert(is_of_type<common_unit(si::kilo<gram>, kilogram), kilogram_>);
-static_assert(is_of_type<common_unit(kilogram, si::kilo<gram>), kilogram_>);
-static_assert(is_of_type<common_unit(mag<1000>* gram, kilogram), kilogram_>);
-static_assert(is_of_type<common_unit(kilogram, mag<1000>* gram), kilogram_>);
+static_assert(is_of_type<common_unit(kilogram, kilogram), std::remove_const_t<decltype(si::kilo<gram>)>>);
+static_assert(is_of_type<common_unit(si::kilo<gram>, kilogram), std::remove_const_t<decltype(si::kilo<gram>)>>);
+static_assert(is_of_type<common_unit(kilogram, si::kilo<gram>), std::remove_const_t<decltype(si::kilo<gram>)>>);
+static_assert(is_of_type<common_unit(mag<1000>* gram, kilogram), std::remove_const_t<decltype(si::kilo<gram>)>>);
+static_assert(is_of_type<common_unit(kilogram, mag<1000>* gram), std::remove_const_t<decltype(si::kilo<gram>)>>);
 static_assert(is_of_type<common_unit(one / second, hertz), hertz_>);
 static_assert(is_of_type<common_unit(hertz, one / second), hertz_>);
 static_assert(is_of_type<common_unit(gram, kilogram), gram_>);