diff --git a/example/avg_velocity.cpp b/example/avg_velocity.cpp
index 1127e9a3..74a09259 100644
--- a/example/avg_velocity.cpp
+++ b/example/avg_velocity.cpp
@@ -22,7 +22,7 @@
 
 #include <units/physical/cgs/velocity.h>
 #include <units/physical/si/velocity.h>
-#include <units/physical/us/velocity.h>
+#include <units/physical/international/velocity.h>
 #include <iostream>
 
 namespace {
diff --git a/example/box_example.cpp b/example/box_example.cpp
index ed2820ed..bc8fcb0f 100644
--- a/example/box_example.cpp
+++ b/example/box_example.cpp
@@ -56,26 +56,26 @@ namespace{
 
 struct Box{
 
-    Box(length::m<> const& l,
-        length::m<> const& w,
-        length::m<> const& h
+    Box(const length::m<> & l,
+        const length::m<> & w,
+        const length::m<> & h
     ): length{l},width{w},height{h}{}
 
     force::N<> filled_weight()const
     {
-        volume::m3<> const volume
+        const volume::m3<>  volume
            = length * width * height;
-        mass::kg<> const mass = contents.density * volume;
+        const mass::kg<>  mass = contents.density * volume;
         return mass * acceleration::g<>;
     }
 
-    length::m<> fill_level(mass::kg<> const & measured_mass)const
+    length::m<> fill_level(const mass::kg<> & measured_mass)const
     {
        return height
           * (measured_mass * acceleration::g<>) / filled_weight();
     }
 
-    volume::m3<> spare_capacity(mass::kg<> const & measured_mass)const
+    volume::m3<> spare_capacity(const  mass::kg<> & measured_mass)const
     {
        return (height - fill_level(measured_mass)) * width * length;
     }
@@ -85,7 +85,7 @@ struct Box{
         density::kgpm3<> density;
     }contents;
 
-    void set_contents_density(density::kgpm3<> const & density_in)
+    void set_contents_density(const density::kgpm3<>  & density_in)
     {
         assert( density_in > air_density );
         contents.density = density_in;
diff --git a/example/capacitor_time_curve.cpp b/example/capacitor_time_curve.cpp
index 3f30b8a4..dc48c9d9 100644
--- a/example/capacitor_time_curve.cpp
+++ b/example/capacitor_time_curve.cpp
@@ -56,13 +56,13 @@ int main()
     std::cout.setf(std::ios_base::fixed,std::ios_base::floatfield);
     std::cout.precision(3);
 
-    auto constexpr C = 0.47uF;
-    auto constexpr V0 = 5.0V;
-    auto constexpr R = 4.7kR;
+    constexpr auto  C = 0.47uF;
+    constexpr auto  V0 = 5.0V;
+    constexpr auto  R = 4.7kR;
 
     for ( auto t = 0ms ; t <= 50ms; ++t  ){
 
-        auto const Vt = V0 * std::exp(-t / (R * C));
+        const auto  Vt = V0 * std::exp(-t / (R * C));
 
         std::cout << "at " << t << " voltage is " ;
 
diff --git a/example/clcpp_response.cpp b/example/clcpp_response.cpp
index 3414caeb..23f2a41d 100644
--- a/example/clcpp_response.cpp
+++ b/example/clcpp_response.cpp
@@ -128,12 +128,13 @@ void simple_quantities()
 {
     using distance = length::m<>;
     using time = time::s<>;
-    distance constexpr km = 1.0km;
-    distance constexpr miles = 1.0mi;
 
-    time constexpr sec = 1s;
-    time constexpr min = 1min;
-    time constexpr hr = 1h;
+    constexpr distance  km = 1.0km;
+    constexpr  distance miles = 1.0mi;
+
+    constexpr time  sec = 1s;
+    constexpr time  min = 1min;
+    constexpr time  hr = 1h;
 
     std::cout << "A physical quantities library can choose the simple\n";
     std::cout << "option to provide output using a single type for each base unit:\n\n"; 
@@ -146,15 +147,14 @@ void simple_quantities()
 
 void quantities_with_typed_units()
 {
-    length::km<> constexpr km = 1km;
-
-    length::mi<> constexpr miles = 1.0mi;
+    constexpr length::km<>  km = 1km;
+    constexpr length::mi<>  miles = 1.0mi;
 
     std::cout.precision(6);
 
-    time::s<> constexpr  sec = 1s;
-    time::min<> constexpr min = 1min;
-    time::h<> constexpr  hr  = 1h;
+    constexpr time::s<>  sec = 1s;
+    constexpr time::min<>  min = 1min;
+    constexpr time::h<>   hr  = 1h;
 
     std::cout << "A more flexible option is to provide separate types for each unit,\n\n"; 
     std::cout << km << '\n';
@@ -163,7 +163,7 @@ void quantities_with_typed_units()
     std::cout << min << '\n';
     std::cout << hr  << "\n\n";
 
-    length::m<> constexpr meter = 1m;
+    constexpr length::m<>  meter = 1m;
     std::cout << "then a wide range of pre-defined units can be defined and converted,\n"
     " for consistency and repeatability across applications:\n\n";
 
diff --git a/example/conversion_factor.cpp b/example/conversion_factor.cpp
index efc1bb1d..c69117f4 100644
--- a/example/conversion_factor.cpp
+++ b/example/conversion_factor.cpp
@@ -48,7 +48,7 @@ namespace {
    }
 
    // get at the units text of the quantity, without its numeric value
-   auto inline constexpr units_str( units::Quantity const & q)
+   auto inline constexpr units_str( const units::Quantity & q)
    {
       typedef std::remove_cvref_t<decltype(q)> qtype;
       return units::detail::unit_text<typename qtype::dimension, typename qtype::unit>();
@@ -74,8 +74,8 @@ int main()
 {
    std::cout << "conversion factor in mpusz/units...\n\n";
 
-   length::m<> constexpr lengthA = 2.0m;
-   length::mm<> constexpr lengthB = lengthA;
+   constexpr length::m<>  lengthA = 2.0m;
+   constexpr length::mm<>  lengthB = lengthA;
 
    std::cout << "lengthA( " << lengthA << " ) and lengthB( " << lengthB << " )\n"
    "represent the same length in different units.\n\n";
diff --git a/example/hello_units.cpp b/example/hello_units.cpp
index c90a6b8b..5aa8b5e4 100644
--- a/example/hello_units.cpp
+++ b/example/hello_units.cpp
@@ -21,7 +21,7 @@
 // SOFTWARE.
 
 #include <units/physical/si/velocity.h>
-#include <units/physical/us/velocity.h>
+#include <units/physical/international/velocity.h>
 #include <units/format.h>
 #include <iostream>
 
diff --git a/src/include/units/physical/iau/length.h b/src/include/units/physical/iau/length.h
index bdf7986d..fd7a92b7 100644
--- a/src/include/units/physical/iau/length.h
+++ b/src/include/units/physical/iau/length.h
@@ -27,9 +27,9 @@
 
 namespace units::iau {
 
-struct light_year : named_scaled_unit<light_year,"ly(iau)",no_prefix,ratio<946073,100000,15>,si::metre> {};
-struct parsec : named_scaled_unit<parsec,"pc(iau)",no_prefix,ratio<1542839,500000,16>,si::metre> {};
-struct angstrom : named_scaled_unit<angstrom,"angstrom(iau)",no_prefix,ratio<1,1,-10>,si::metre> {};
+struct light_year : named_scaled_unit<light_year,"ly",no_prefix,ratio<946073,100000,15>,si::metre> {};
+struct parsec : named_scaled_unit<parsec,"pc",no_prefix,ratio<1542839,500000,16>,si::metre> {};
+struct angstrom : named_scaled_unit<angstrom,"angstrom",no_prefix,ratio<1,1,-10>,si::metre> {};
 
 inline namespace literals {
 
diff --git a/src/include/units/physical/us/area.h b/src/include/units/physical/international/area.h
similarity index 95%
rename from src/include/units/physical/us/area.h
rename to src/include/units/physical/international/area.h
index 713afcc4..9ed8f0d1 100644
--- a/src/include/units/physical/us/area.h
+++ b/src/include/units/physical/international/area.h
@@ -25,7 +25,7 @@
 #include <units/physical/si/area.h>
 #include <units/physical/international/length.h>
 
-namespace units::us {
+namespace units::international {
 
 struct square_foot : deduced_unit<square_foot, si::dim_area, international::foot> {};
 
@@ -37,4 +37,4 @@ constexpr auto operator"" ft2(long double l) { return si::area<square_foot, long
 
 }  // namespace literals
 
-}  // namespace units::us
+}  // namespace units::international
diff --git a/src/include/units/physical/international/length.h b/src/include/units/physical/international/length.h
index 8ff84d45..328ac9f6 100644
--- a/src/include/units/physical/international/length.h
+++ b/src/include/units/physical/international/length.h
@@ -35,7 +35,6 @@ namespace units::international {
 //https://en.wikipedia.org/wiki/International_yard_and_pound
 struct yard : named_scaled_unit<yard, "yd", no_prefix, ratio<9'144, 1'000,-1>, si::metre> {};
 
-
 //international foot
 //https://en.wikipedia.org/wiki/Foot_(unit)#International_foot
 struct foot : named_scaled_unit<foot, "ft", no_prefix, ratio<3'048,1'000,-1>, si::metre> {};
@@ -55,10 +54,9 @@ struct mile : named_scaled_unit<mile, "mi", no_prefix, ratio<25'146,15'625,3>, s
 //https://en.wikipedia.org/wiki/Mile#Nautical_mile
 struct nautical_mile : named_scaled_unit<nautical_mile,"mi(naut)",no_prefix, ratio<463,250,3>,si::metre> {};
 
-#if 0
+//TODO thou
 //https://en.wikipedia.org/wiki/Thousandth_of_an_inch
-struct thou : named_scaled_unit<thou,"thou",no_prefix,ratio<127,50,-5>,si::metre> {};
-#endif
+//struct thou : named_scaled_unit<thou,"thou",no_prefix,ratio<127,50,-5>,si::metre> {};
 // different name for thou
 //https://en.wikipedia.org/wiki/Thousandth_of_an_inch
 struct mil : named_scaled_unit<mil,"mil",no_prefix,ratio<127,50,-5>,si::metre> {};
@@ -89,11 +87,10 @@ constexpr auto operator"" mi(long double l) { return si::length<mile, long doubl
 constexpr auto operator"" naut_mi(unsigned long long l) { return si::length<nautical_mile, std::int64_t>(l); }
 constexpr auto operator"" naut_mi(long double l) { return si::length<nautical_mile, long double>(l); }
 
-#if 0
-// thou
-constexpr auto operator"" thou(unsigned long long l) { return si::length<thou, std::int64_t>(l); }
-constexpr auto operator"" thou(long double l) { return si::length<thou, long double>(l); }
-#endif
+//TODO thou
+//constexpr auto operator"" thou(unsigned long long l) { return si::length<thou, std::int64_t>(l); }
+//constexpr auto operator"" thou(long double l) { return si::length<thou, long double>(l); }
+
 // mil
 constexpr auto operator"" mil(unsigned long long l) { return si::length<mil, std::int64_t>(l); }
 constexpr auto operator"" mil(long double l) { return si::length<mil, long double>(l); }
diff --git a/src/include/units/physical/us/velocity.h b/src/include/units/physical/international/velocity.h
similarity index 95%
rename from src/include/units/physical/us/velocity.h
rename to src/include/units/physical/international/velocity.h
index b01d3af9..ca678fd7 100644
--- a/src/include/units/physical/us/velocity.h
+++ b/src/include/units/physical/international/velocity.h
@@ -25,7 +25,7 @@
 #include <units/physical/si/velocity.h>
 #include <units/physical/international/length.h>
 
-namespace units::us {
+namespace units::international {
 
 struct mile_per_hour : deduced_unit<mile_per_hour, si::dim_velocity, international::mile, si::hour> {};
 
@@ -37,4 +37,4 @@ constexpr auto operator"" mph(long double l) { return si::velocity<mile_per_hour
 
 }  // namespace literals
 
-}  // namespace units::us
+}  // namespace units::international
diff --git a/src/include/units/physical/us/volume.h b/src/include/units/physical/international/volume.h
similarity index 95%
rename from src/include/units/physical/us/volume.h
rename to src/include/units/physical/international/volume.h
index 4e315b42..a5de2e39 100644
--- a/src/include/units/physical/us/volume.h
+++ b/src/include/units/physical/international/volume.h
@@ -25,7 +25,7 @@
 #include <units/physical/si/volume.h>
 #include <units/physical/international/length.h>
 
-namespace units::us {
+namespace units::international {
 
 struct cubic_foot : deduced_unit<cubic_foot, si::dim_volume, international::foot> {};
 
@@ -37,4 +37,4 @@ constexpr auto operator""ft3(long double l) { return si::volume<cubic_foot, long
 
 }  // namespace literals
 
-}  // namespace units::us
+}  // namespace units::international
diff --git a/src/include/units/physical/si/resistance.h b/src/include/units/physical/si/resistance.h
index c7ab24a9..fc4ff7b8 100644
--- a/src/include/units/physical/si/resistance.h
+++ b/src/include/units/physical/si/resistance.h
@@ -30,7 +30,7 @@
 
 namespace units::si {
 
-struct ohm : named_unit<ohm, "R", prefix> {};
+struct ohm : named_unit<ohm, "Ω", prefix> {};
 struct milliohm : prefixed_unit<milliohm, milli, ohm> {};
 struct kiloohm : prefixed_unit<kiloohm, kilo, ohm> {};
 struct megaohm : prefixed_unit<megaohm, mega, ohm> {};
@@ -43,7 +43,7 @@ using resistance = quantity<dim_resistance, U, Rep>;
 inline namespace literals {
 
 //R
-constexpr auto operator""R(unsigned long long l) { return resistance<ohm, std::int64_t>(l); }
+constexpr auto operator""_R(unsigned long long l) { return resistance<ohm, std::int64_t>(l); }
 constexpr auto operator""_R(long double l) { return resistance<ohm, long double>(l); }
 
 //mR
diff --git a/src/include/units/physical/us/length.h b/src/include/units/physical/us/length.h
index bc4f5782..1abd9f75 100644
--- a/src/include/units/physical/us/length.h
+++ b/src/include/units/physical/us/length.h
@@ -26,7 +26,6 @@
 
 namespace units::us {
 
-#if 1
 //https://en.wikipedia.org/wiki/Foot_(unit)#US_survey_foot
 //https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors#B6
 //struct foot : named_scaled_unit<foot,"ft(us)",no_prefix,ratio<3'048,1'000,-1>, si::metre> {};
@@ -39,7 +38,7 @@ struct fathom : named_scaled_unit<fathom,"fathom(us)",no_prefix,ratio<6,1>,us::f
 
 //https://en.wikipedia.org/wiki/Mile#U.S._survey_mile
 //https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors#B6
-struct mile : named_scaled_unit<mile,"mile(us)",no_prefix,ratio<5280,1000,3>,us::foot> {};
+struct mile : named_scaled_unit<mile,"mi(us)",no_prefix,ratio<5280,1000,3>,us::foot> {};
 
 inline namespace literals {
 
@@ -56,5 +55,5 @@ constexpr auto operator"" mi_us(unsigned long long l) { return si::length<units:
 constexpr auto operator"" mi_us(long double l) { return si::length<units::us::mile, long double>(l); }
 
 }  // namespace literals
-#endif
+
 }  // namespace units::us
diff --git a/test/unit_test/runtime/fmt_units_test.cpp b/test/unit_test/runtime/fmt_units_test.cpp
index a1a8f3cd..e46a7a70 100644
--- a/test/unit_test/runtime/fmt_units_test.cpp
+++ b/test/unit_test/runtime/fmt_units_test.cpp
@@ -26,14 +26,26 @@
 #include "units/physical/si/velocity.h"
 #include "units/physical/si/volume.h"
 #include "units/physical/si/surface_tension.h"
-#include "units/physical/us/area.h"
-#include "units/physical/us/velocity.h"
-#include "units/physical/us/volume.h"
+#include "units/physical/us/length.h"
+#include "units/physical/imperial/length.h"
+#include "units/physical/international/length.h"
+#include "units/physical/international/area.h"
+#include "units/physical/international/volume.h"
+#include "units/physical/international/velocity.h"
+#include "units/physical/iau/length.h"
+#include "units/physical/typographic/length.h"
+#include "units/physical/si/density.h"
+#include "units/physical/si/resistance.h"
+#include "units/physical/si/voltage.h"
 #include "units/format.h"
 #include <catch2/catch.hpp>
 
 using namespace units::si;
+using namespace units::international;
 using namespace units::us;
+using namespace units::iau;
+using namespace units::imperial;
+using namespace units::typographic;
 
 TEST_CASE("fmt::format on synthesized unit symbols", "[text][fmt]")
 {
@@ -49,6 +61,27 @@ TEST_CASE("fmt::format on synthesized unit symbols", "[text][fmt]")
     CHECK(fmt::format("{}", 1mm) == "1 mm");
     CHECK(fmt::format("{}", 1cm) == "1 cm");
     CHECK(fmt::format("{}", 1km) == "1 km");
+    CHECK(fmt::format("{}", 1ft) == "1 ft");
+    CHECK(fmt::format("{}", 1ft_us) == "1 ft(us)");
+    CHECK(fmt::format("{}", 1yd) == "1 yd");
+    CHECK(fmt::format("{}", 1in) == "1 in");
+    CHECK(fmt::format("{}", 1fathom) == "1 fathom");
+    CHECK(fmt::format("{}", 1fathom_us) == "1 fathom(us)");
+    CHECK(fmt::format("{}", 1mi) == "1 mi");
+    CHECK(fmt::format("{}", 1mi_us) == "1 mi(us)");
+    CHECK(fmt::format("{}", 1naut_mi) == "1 mi(naut)");
+    CHECK(fmt::format("{}", 1ch) == "1 ch");
+    CHECK(fmt::format("{}", 1rd) == "1 rd");
+    CHECK(fmt::format("{}", 1mil) == "1 mil");
+    CHECK(fmt::format("{}", 1pc) == "1 pc");
+    CHECK(fmt::format("{}", 1ly) == "1 ly");
+    CHECK(fmt::format("{}", 1pc) == "1 pc");
+    CHECK(fmt::format("{}", 1angstrom) == "1 angstrom");
+    CHECK(fmt::format("{}", 1au) == "1 au");
+    CHECK(fmt::format("{}", 1pica_comp) == "1 pica(comp)");
+    CHECK(fmt::format("{}", 1pica_prn) == "1 pica(prn)");
+    CHECK(fmt::format("{}", 1point_comp) == "1 point(comp)");
+    CHECK(fmt::format("{}", 1point_prn) == "1 point(prn)");
   }
 
   SECTION("mass")
@@ -65,6 +98,28 @@ TEST_CASE("fmt::format on synthesized unit symbols", "[text][fmt]")
     CHECK(fmt::format("{}", 1ft2) == "1 ft²");
   }
 
+  SECTION("density")
+  {
+      CHECK(fmt::format("{}", 1kgpm3) == "1 kg/m³");
+  }
+
+  SECTION("resistance")
+  {
+      CHECK(fmt::format("{}", 1_R) == "1 Ω");
+      CHECK(fmt::format("{}", 1kR) == "1 kΩ");
+      CHECK(fmt::format("{}", 1mR) == "1 mΩ");
+      CHECK(fmt::format("{}", 1MR) == "1 MΩ");
+  }
+
+  SECTION("voltage")
+  {
+     CHECK(fmt::format("{}", 1V) == "1 V");
+     CHECK(fmt::format("{}", 1mV) == "1 mV");
+     CHECK(fmt::format("{}", 1uV) == "1 µV");
+     CHECK(fmt::format("{}", 1nV) == "1 nV");
+     CHECK(fmt::format("{}", 1pV) == "1 pV");
+  }
+
   SECTION("volume")
   {
     CHECK(fmt::format("{}", 1m3) == "1 m³");
diff --git a/test/unit_test/static/us_test.cpp b/test/unit_test/static/us_test.cpp
index 843f0a21..b03a90e3 100644
--- a/test/unit_test/static/us_test.cpp
+++ b/test/unit_test/static/us_test.cpp
@@ -25,10 +25,10 @@
 #include <units/physical/international/length.h>
 #include <units/physical/si/velocity.h>
 #include <units/physical/si/volume.h>
-#include <units/physical/us/area.h>
+#include <units/physical/international/area.h>
 #include <units/physical/us/length.h>
-#include <units/physical/us/velocity.h>
-#include <units/physical/us/volume.h>
+#include <units/physical/international/velocity.h>
+#include <units/physical/international/volume.h>
 #include <utility>
 
 namespace {