diff --git a/CMakeLists.txt b/CMakeLists.txt
index 933c9274..e003679a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,7 +21,7 @@
 # SOFTWARE.
 
 cmake_minimum_required(VERSION 3.15)
-project(mp-units
+project(mp-units-dev
     LANGUAGES CXX
 )
 
diff --git a/example/CMakeLists.txt b/example/CMakeLists.txt
index fdab19df..7f9926ec 100644
--- a/example/CMakeLists.txt
+++ b/example/CMakeLists.txt
@@ -22,26 +22,27 @@
 
 cmake_minimum_required(VERSION 3.2)
 
+#
+# add_example(target <depependencies>...)
+#
 function(add_example target)
     add_executable(${target} ${target}.cpp)
-    target_link_libraries(${target} PRIVATE mp-units::mp-units)
+    target_link_libraries(${target} PRIVATE ${ARGN})
 endfunction()
 
-add_example(box_example)
-add_example(capacitor_time_curve)
-add_example(clcpp_response)
-add_example(conversion_factor)
-add_example(custom_systems)
-add_example(experimental_angle)
-add_example(foot_pound_second)
-add_example(kalman_filter-alpha_beta_filter_example2)
-
-add_example(measurement)
-add_example(unknown_dimension)
-
-add_example(avg_speed)
-add_example(hello_units)
-add_example(total_energy)
+add_example(avg_speed mp-units::si mp-units::si-cgs mp-units::si-international)
+add_example(box_example mp-units::si)
+add_example(capacitor_time_curve mp-units::si)
+add_example(clcpp_response mp-units::si mp-units::si-iau mp-units::si-imperial mp-units::si-international mp-units::si-typographic mp-units::si-us)
+add_example(conversion_factor mp-units::si)
+add_example(custom_systems mp-units::si)
+add_example(experimental_angle mp-units::si)
+add_example(foot_pound_second mp-units::si-fps)
+add_example(hello_units mp-units::si mp-units::si-international)
+add_example(kalman_filter-alpha_beta_filter_example2 mp-units::si)
+add_example(measurement mp-units::si)
+add_example(total_energy mp-units::si mp-units::isq-natural)
+add_example(unknown_dimension mp-units::si)
 
 if(NOT UNITS_LIBCXX)
     add_executable(glide_computer
@@ -49,14 +50,11 @@ if(NOT UNITS_LIBCXX)
         glide_computer.cpp glide_computer.h
         glide_computer_example.cpp
     )
-    target_link_libraries(glide_computer PRIVATE mp-units::mp-units)
+    target_link_libraries(glide_computer PRIVATE mp-units::si mp-units::si-international)
 
     find_package(linear_algebra CONFIG REQUIRED)
-    add_example(linear_algebra)
-    target_link_libraries(linear_algebra
-        PRIVATE
-            linear_algebra::linear_algebra
-    )
+    add_example(linear_algebra mp-units::si)
+    target_link_libraries(linear_algebra PRIVATE linear_algebra::linear_algebra)
 endif()
 
 add_subdirectory(alternative_namespaces)
diff --git a/example/alternative_namespaces/CMakeLists.txt b/example/alternative_namespaces/CMakeLists.txt
index 509795e7..139c9d94 100644
--- a/example/alternative_namespaces/CMakeLists.txt
+++ b/example/alternative_namespaces/CMakeLists.txt
@@ -27,8 +27,8 @@ function(add_example target)
     target_link_libraries(${target}_alt PRIVATE mp-units::mp-units)
 endfunction()
 
-add_example(box_example)
-add_example(capacitor_time_curve)
-add_example(clcpp_response)
-add_example(conversion_factor)
-add_example(timer)
+add_example(box_example mp-units::si)
+add_example(capacitor_time_curve mp-units::si)
+add_example(clcpp_response mp-units::si)
+add_example(conversion_factor mp-units::si)
+add_example(timer mp-units::si)
diff --git a/example/avg_speed.cpp b/example/avg_speed.cpp
index e760d8ea..2340e5f1 100644
--- a/example/avg_speed.cpp
+++ b/example/avg_speed.cpp
@@ -46,7 +46,7 @@ fixed_double_si_avg_speed(si::length<si::metre> d,
 
 template<typename U1, typename R1, typename U2, typename R2>
 constexpr Speed auto si_avg_speed(si::length<U1, R1> d,
-                                     si::time<U2, R2> t)
+                                  si::time<U2, R2> t)
 {
   return d / t;
 }
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index bb269aa0..01936de7 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -21,92 +21,34 @@
 # SOFTWARE.
 
 cmake_minimum_required(VERSION 3.15)
-
 project(mp-units
     VERSION 0.7.0
     LANGUAGES CXX
 )
 
-set(UNITS_DOWNCAST_MODE ON CACHE STRING "Select downcasting mode")
-set_property(CACHE UNITS_DOWNCAST_MODE PROPERTY STRINGS AUTO ON OFF)
-
-# check if libc++ is being used
-if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
-    message(CHECK_START "Checking if libc++ is being used")
-    list(APPEND CMAKE_MESSAGE_INDENT "  ")
-
-    include(CheckSymbolExists)
-    check_symbol_exists(_LIBCPP_VERSION "ciso646" UNITS_LIBCXX)
-
-    list(POP_BACK CMAKE_MESSAGE_INDENT)
-    if(UNITS_LIBCXX)
-        message(CHECK_PASS "found")
-    else()
-        message(CHECK_FAIL "not found")
-    endif()
-endif()
-
-find_package(fmt CONFIG REQUIRED)
-find_package(gsl-lite CONFIG REQUIRED)
-
-# library definition
-add_library(mp-units INTERFACE)
-target_compile_features(mp-units INTERFACE cxx_std_20)
-target_link_libraries(mp-units
-    INTERFACE
-        fmt::fmt
-        gsl::gsl-lite
-)
-target_include_directories(mp-units
-    INTERFACE
-        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
-        $<INSTALL_INTERFACE:include>
-)
-
-if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
-    if(UNITS_LIBCXX)
-        find_package(range-v3)
-        target_link_libraries(mp-units
-            INTERFACE
-                range-v3::range-v3
-        )
-    endif()
-elseif(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
-    target_compile_options(mp-units
-        INTERFACE
-            -Wno-non-template-friend
-    )
-elseif(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
-    target_compile_options(mp-units
-        INTERFACE
-            /utf-8  # Specifies both the source character set and the execution character set as UTF-8
-    )
-endif()
-
-if(DEFINED UNITS_DOWNCAST_MODE)
-    set(downcast_mode_options OFF ON AUTO)
-    list(FIND downcast_mode_options "${UNITS_DOWNCAST_MODE}" downcast_mode)
-    if(downcast_mode EQUAL -1)
-        message(FATAL_ERROR "'UNITS_DOWNCAST_MODE' should be one of ${downcast_mode_options} ('${UNITS_DOWNCAST_MODE}' received)")
-    else()
-        message(STATUS "UNITS_DOWNCAST_MODE: ${UNITS_DOWNCAST_MODE}")
-        target_compile_definitions(mp-units INTERFACE UNITS_DOWNCAST_MODE=${downcast_mode})
-    endif()
-endif()
-
-add_library(mp-units::mp-units ALIAS mp-units)
-
-# installation info
-include(CMakePackageConfigHelpers)
-write_basic_package_version_file(mp-unitsConfigVersion.cmake COMPATIBILITY SameMajorVersion)
+list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake")
 
 include(GNUInstallDirs)
-install(TARGETS mp-units EXPORT mp-unitsTargets)
+add_subdirectory(core)
+add_subdirectory(systems)
+
+# project-wide wrapper
+add_library(mp-units INTERFACE)
+target_link_libraries(mp-units INTERFACE
+    mp-units::core
+    mp-units::systems
+)
+add_library(mp-units::mp-units ALIAS mp-units)
+
+# installation
 install(EXPORT mp-unitsTargets
     DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/mp-units
     NAMESPACE mp-units::
 )
+
+include(CMakePackageConfigHelpers)
+write_basic_package_version_file(mp-unitsConfigVersion.cmake COMPATIBILITY SameMajorVersion)
+
 install(FILES mp-unitsConfig.cmake ${CMAKE_CURRENT_BINARY_DIR}/mp-unitsConfigVersion.cmake
     DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/mp-units
 )
-install(DIRECTORY include/units TYPE INCLUDE)
diff --git a/src/cmake/AddSystem.cmake b/src/cmake/AddSystem.cmake
new file mode 100644
index 00000000..75eee0d3
--- /dev/null
+++ b/src/cmake/AddSystem.cmake
@@ -0,0 +1,40 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+#
+# add_system(SystemName <depependencies>...)
+#
+function(add_system name)
+    add_library(mp-units-${name} INTERFACE)
+    target_link_libraries(mp-units-${name} INTERFACE ${ARGN})
+    target_include_directories(mp-units-${name} INTERFACE
+        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+        $<INSTALL_INTERFACE:include>
+    )
+    set_target_properties(mp-units-${name} PROPERTIES EXPORT_NAME ${name})
+    add_library(mp-units::${name} ALIAS mp-units-${name})
+
+    install(TARGETS mp-units-${name} EXPORT mp-unitsTargets)
+    install(DIRECTORY include/units TYPE INCLUDE)
+endfunction()
diff --git a/src/cmake/CheckLibcxxInUse.cmake b/src/cmake/CheckLibcxxInUse.cmake
new file mode 100644
index 00000000..975828fa
--- /dev/null
+++ b/src/cmake/CheckLibcxxInUse.cmake
@@ -0,0 +1,41 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+function(check_libcxx_in_use variable)
+    if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+        message(CHECK_START "Checking if libc++ is being used")
+        list(APPEND CMAKE_MESSAGE_INDENT "  ")
+
+        include(CheckSymbolExists)
+        check_symbol_exists(_LIBCPP_VERSION "ciso646" ${variable})
+        set(${variable} ${${variable}} PARENT_SCOPE)
+
+        list(POP_BACK CMAKE_MESSAGE_INDENT)
+        if(UNITS_LIBCXX)
+            message(CHECK_PASS "found")
+        else()
+            message(CHECK_FAIL "not found")
+        endif()
+    endif()
+endfunction()
diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
new file mode 100644
index 00000000..2b5381b0
--- /dev/null
+++ b/src/core/CMakeLists.txt
@@ -0,0 +1,80 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+# core library options
+set(UNITS_DOWNCAST_MODE ON CACHE STRING "Select downcasting mode")
+set_property(CACHE UNITS_DOWNCAST_MODE PROPERTY STRINGS AUTO ON OFF)
+
+# find dependencies
+find_package(fmt CONFIG REQUIRED)
+find_package(gsl-lite CONFIG REQUIRED)
+
+# check if libc++ is being used
+include(CheckLibcxxInUse)
+check_libcxx_in_use(UNITS_LIBCXX)
+
+# core library definition
+add_library(mp-units-core INTERFACE)
+target_compile_features(mp-units-core INTERFACE cxx_std_20)
+target_link_libraries(mp-units-core INTERFACE
+    fmt::fmt
+    gsl::gsl-lite
+)
+target_include_directories(mp-units-core INTERFACE
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+    $<INSTALL_INTERFACE:include>
+)
+
+if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    if(UNITS_LIBCXX)
+        find_package(range-v3)
+        target_link_libraries(mp-units-core INTERFACE range-v3::range-v3)
+    endif()
+elseif(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+    target_compile_options(mp-units-core INTERFACE
+        -Wno-non-template-friend
+    )
+elseif(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+    target_compile_options(mp-units-core INTERFACE
+        /utf-8  # Specifies both the source character set and the execution character set as UTF-8
+    )
+endif()
+
+if(DEFINED UNITS_DOWNCAST_MODE)
+    set(downcast_mode_options OFF ON AUTO)
+    list(FIND downcast_mode_options "${UNITS_DOWNCAST_MODE}" downcast_mode)
+    if(downcast_mode EQUAL -1)
+        message(FATAL_ERROR "'UNITS_DOWNCAST_MODE' should be one of ${downcast_mode_options} ('${UNITS_DOWNCAST_MODE}' received)")
+    else()
+        message(STATUS "UNITS_DOWNCAST_MODE: ${UNITS_DOWNCAST_MODE}")
+        target_compile_definitions(mp-units-core INTERFACE UNITS_DOWNCAST_MODE=${downcast_mode})
+    endif()
+endif()
+
+set_target_properties(mp-units-core PROPERTIES EXPORT_NAME core)
+add_library(mp-units::core ALIAS mp-units-core)
+
+# installation
+install(TARGETS mp-units-core EXPORT mp-unitsTargets)
+install(DIRECTORY include/units TYPE INCLUDE)
diff --git a/src/include/units/base_dimension.h b/src/core/include/units/base_dimension.h
similarity index 100%
rename from src/include/units/base_dimension.h
rename to src/core/include/units/base_dimension.h
diff --git a/src/include/units/bits/base_units_ratio.h b/src/core/include/units/bits/base_units_ratio.h
similarity index 100%
rename from src/include/units/bits/base_units_ratio.h
rename to src/core/include/units/bits/base_units_ratio.h
diff --git a/src/include/units/bits/basic_concepts.h b/src/core/include/units/bits/basic_concepts.h
similarity index 100%
rename from src/include/units/bits/basic_concepts.h
rename to src/core/include/units/bits/basic_concepts.h
diff --git a/src/include/units/bits/common_quantity.h b/src/core/include/units/bits/common_quantity.h
similarity index 100%
rename from src/include/units/bits/common_quantity.h
rename to src/core/include/units/bits/common_quantity.h
diff --git a/src/include/units/bits/constexpr_math.h b/src/core/include/units/bits/constexpr_math.h
similarity index 100%
rename from src/include/units/bits/constexpr_math.h
rename to src/core/include/units/bits/constexpr_math.h
diff --git a/src/include/units/bits/deduced_symbol_text.h b/src/core/include/units/bits/deduced_symbol_text.h
similarity index 100%
rename from src/include/units/bits/deduced_symbol_text.h
rename to src/core/include/units/bits/deduced_symbol_text.h
diff --git a/src/include/units/bits/deduced_unit.h b/src/core/include/units/bits/deduced_unit.h
similarity index 100%
rename from src/include/units/bits/deduced_unit.h
rename to src/core/include/units/bits/deduced_unit.h
diff --git a/src/include/units/bits/derived_dimension_base.h b/src/core/include/units/bits/derived_dimension_base.h
similarity index 100%
rename from src/include/units/bits/derived_dimension_base.h
rename to src/core/include/units/bits/derived_dimension_base.h
diff --git a/src/include/units/bits/dim_consolidate.h b/src/core/include/units/bits/dim_consolidate.h
similarity index 100%
rename from src/include/units/bits/dim_consolidate.h
rename to src/core/include/units/bits/dim_consolidate.h
diff --git a/src/include/units/bits/dim_unpack.h b/src/core/include/units/bits/dim_unpack.h
similarity index 100%
rename from src/include/units/bits/dim_unpack.h
rename to src/core/include/units/bits/dim_unpack.h
diff --git a/src/include/units/bits/dimension_op.h b/src/core/include/units/bits/dimension_op.h
similarity index 100%
rename from src/include/units/bits/dimension_op.h
rename to src/core/include/units/bits/dimension_op.h
diff --git a/src/include/units/bits/equivalent.h b/src/core/include/units/bits/equivalent.h
similarity index 100%
rename from src/include/units/bits/equivalent.h
rename to src/core/include/units/bits/equivalent.h
diff --git a/src/include/units/bits/external/downcasting.h b/src/core/include/units/bits/external/downcasting.h
similarity index 100%
rename from src/include/units/bits/external/downcasting.h
rename to src/core/include/units/bits/external/downcasting.h
diff --git a/src/include/units/bits/external/fixed_string.h b/src/core/include/units/bits/external/fixed_string.h
similarity index 100%
rename from src/include/units/bits/external/fixed_string.h
rename to src/core/include/units/bits/external/fixed_string.h
diff --git a/src/include/units/bits/external/fixed_string_io.h b/src/core/include/units/bits/external/fixed_string_io.h
similarity index 100%
rename from src/include/units/bits/external/fixed_string_io.h
rename to src/core/include/units/bits/external/fixed_string_io.h
diff --git a/src/include/units/bits/external/hacks.h b/src/core/include/units/bits/external/hacks.h
similarity index 100%
rename from src/include/units/bits/external/hacks.h
rename to src/core/include/units/bits/external/hacks.h
diff --git a/src/include/units/bits/external/text_tools.h b/src/core/include/units/bits/external/text_tools.h
similarity index 100%
rename from src/include/units/bits/external/text_tools.h
rename to src/core/include/units/bits/external/text_tools.h
diff --git a/src/include/units/bits/external/type_list.h b/src/core/include/units/bits/external/type_list.h
similarity index 100%
rename from src/include/units/bits/external/type_list.h
rename to src/core/include/units/bits/external/type_list.h
diff --git a/src/include/units/bits/external/type_traits.h b/src/core/include/units/bits/external/type_traits.h
similarity index 100%
rename from src/include/units/bits/external/type_traits.h
rename to src/core/include/units/bits/external/type_traits.h
diff --git a/src/include/units/bits/math_concepts.h b/src/core/include/units/bits/math_concepts.h
similarity index 100%
rename from src/include/units/bits/math_concepts.h
rename to src/core/include/units/bits/math_concepts.h
diff --git a/src/include/units/bits/pow.h b/src/core/include/units/bits/pow.h
similarity index 100%
rename from src/include/units/bits/pow.h
rename to src/core/include/units/bits/pow.h
diff --git a/src/include/units/bits/quantity_of.h b/src/core/include/units/bits/quantity_of.h
similarity index 100%
rename from src/include/units/bits/quantity_of.h
rename to src/core/include/units/bits/quantity_of.h
diff --git a/src/include/units/bits/ratio_maths.h b/src/core/include/units/bits/ratio_maths.h
similarity index 100%
rename from src/include/units/bits/ratio_maths.h
rename to src/core/include/units/bits/ratio_maths.h
diff --git a/src/include/units/bits/root.h b/src/core/include/units/bits/root.h
similarity index 100%
rename from src/include/units/bits/root.h
rename to src/core/include/units/bits/root.h
diff --git a/src/include/units/bits/unit_text.h b/src/core/include/units/bits/unit_text.h
similarity index 100%
rename from src/include/units/bits/unit_text.h
rename to src/core/include/units/bits/unit_text.h
diff --git a/src/include/units/chrono.h b/src/core/include/units/chrono.h
similarity index 100%
rename from src/include/units/chrono.h
rename to src/core/include/units/chrono.h
diff --git a/src/include/units/concepts.h b/src/core/include/units/concepts.h
similarity index 100%
rename from src/include/units/concepts.h
rename to src/core/include/units/concepts.h
diff --git a/src/include/units/customization_points.h b/src/core/include/units/customization_points.h
similarity index 100%
rename from src/include/units/customization_points.h
rename to src/core/include/units/customization_points.h
diff --git a/src/include/units/derived_dimension.h b/src/core/include/units/derived_dimension.h
similarity index 100%
rename from src/include/units/derived_dimension.h
rename to src/core/include/units/derived_dimension.h
diff --git a/src/include/units/exponent.h b/src/core/include/units/exponent.h
similarity index 100%
rename from src/include/units/exponent.h
rename to src/core/include/units/exponent.h
diff --git a/src/include/units/format.h b/src/core/include/units/format.h
similarity index 100%
rename from src/include/units/format.h
rename to src/core/include/units/format.h
diff --git a/src/include/units/generic/angle.h b/src/core/include/units/generic/angle.h
similarity index 100%
rename from src/include/units/generic/angle.h
rename to src/core/include/units/generic/angle.h
diff --git a/src/include/units/generic/dimensionless.h b/src/core/include/units/generic/dimensionless.h
similarity index 100%
rename from src/include/units/generic/dimensionless.h
rename to src/core/include/units/generic/dimensionless.h
diff --git a/src/include/units/kind.h b/src/core/include/units/kind.h
similarity index 100%
rename from src/include/units/kind.h
rename to src/core/include/units/kind.h
diff --git a/src/include/units/math.h b/src/core/include/units/math.h
similarity index 100%
rename from src/include/units/math.h
rename to src/core/include/units/math.h
diff --git a/src/include/units/one_rep.h b/src/core/include/units/one_rep.h
similarity index 100%
rename from src/include/units/one_rep.h
rename to src/core/include/units/one_rep.h
diff --git a/src/include/units/prefix.h b/src/core/include/units/prefix.h
similarity index 100%
rename from src/include/units/prefix.h
rename to src/core/include/units/prefix.h
diff --git a/src/include/units/quantity.h b/src/core/include/units/quantity.h
similarity index 100%
rename from src/include/units/quantity.h
rename to src/core/include/units/quantity.h
diff --git a/src/include/units/quantity_cast.h b/src/core/include/units/quantity_cast.h
similarity index 100%
rename from src/include/units/quantity_cast.h
rename to src/core/include/units/quantity_cast.h
diff --git a/src/include/units/quantity_io.h b/src/core/include/units/quantity_io.h
similarity index 100%
rename from src/include/units/quantity_io.h
rename to src/core/include/units/quantity_io.h
diff --git a/src/include/units/quantity_kind.h b/src/core/include/units/quantity_kind.h
similarity index 100%
rename from src/include/units/quantity_kind.h
rename to src/core/include/units/quantity_kind.h
diff --git a/src/include/units/quantity_point.h b/src/core/include/units/quantity_point.h
similarity index 100%
rename from src/include/units/quantity_point.h
rename to src/core/include/units/quantity_point.h
diff --git a/src/include/units/quantity_point_kind.h b/src/core/include/units/quantity_point_kind.h
similarity index 100%
rename from src/include/units/quantity_point_kind.h
rename to src/core/include/units/quantity_point_kind.h
diff --git a/src/include/units/random.h b/src/core/include/units/random.h
similarity index 100%
rename from src/include/units/random.h
rename to src/core/include/units/random.h
diff --git a/src/include/units/ratio.h b/src/core/include/units/ratio.h
similarity index 100%
rename from src/include/units/ratio.h
rename to src/core/include/units/ratio.h
diff --git a/src/include/units/symbol_text.h b/src/core/include/units/symbol_text.h
similarity index 100%
rename from src/include/units/symbol_text.h
rename to src/core/include/units/symbol_text.h
diff --git a/src/include/units/unit.h b/src/core/include/units/unit.h
similarity index 100%
rename from src/include/units/unit.h
rename to src/core/include/units/unit.h
diff --git a/src/systems/CMakeLists.txt b/src/systems/CMakeLists.txt
new file mode 100644
index 00000000..af3ce969
--- /dev/null
+++ b/src/systems/CMakeLists.txt
@@ -0,0 +1,55 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+include(AddSystem)
+
+# systems
+add_subdirectory(data)
+add_subdirectory(isq)
+add_subdirectory(isq-natural)
+add_subdirectory(si)
+add_subdirectory(si-cgs)
+add_subdirectory(si-fps)
+add_subdirectory(si-iau)
+add_subdirectory(si-imperial)
+add_subdirectory(si-international)
+add_subdirectory(si-typographic)
+add_subdirectory(si-us)
+
+# wrapper for all the systems
+add_library(mp-units-systems INTERFACE)
+target_link_libraries(mp-units-systems INTERFACE
+    mp-units::data
+    mp-units::isq
+    mp-units::isq-natural
+    mp-units::si
+    mp-units::si-cgs
+    mp-units::si-fps
+    mp-units::si-iau
+    mp-units::si-imperial
+    mp-units::si-international
+    mp-units::si-typographic
+    mp-units::si-us
+)
+add_library(mp-units::systems ALIAS mp-units-systems)
diff --git a/src/systems/data/CMakeLists.txt b/src/systems/data/CMakeLists.txt
new file mode 100644
index 00000000..5e31bf59
--- /dev/null
+++ b/src/systems/data/CMakeLists.txt
@@ -0,0 +1,25 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+add_system(data mp-units::core)
diff --git a/src/include/units/data/bitrate.h b/src/systems/data/include/units/data/bitrate.h
similarity index 100%
rename from src/include/units/data/bitrate.h
rename to src/systems/data/include/units/data/bitrate.h
diff --git a/src/include/units/data/data.h b/src/systems/data/include/units/data/data.h
similarity index 100%
rename from src/include/units/data/data.h
rename to src/systems/data/include/units/data/data.h
diff --git a/src/include/units/data/information.h b/src/systems/data/include/units/data/information.h
similarity index 100%
rename from src/include/units/data/information.h
rename to src/systems/data/include/units/data/information.h
diff --git a/src/include/units/data/prefixes.h b/src/systems/data/include/units/data/prefixes.h
similarity index 100%
rename from src/include/units/data/prefixes.h
rename to src/systems/data/include/units/data/prefixes.h
diff --git a/src/systems/isq-natural/CMakeLists.txt b/src/systems/isq-natural/CMakeLists.txt
new file mode 100644
index 00000000..684e71da
--- /dev/null
+++ b/src/systems/isq-natural/CMakeLists.txt
@@ -0,0 +1,25 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+add_system(isq-natural mp-units::isq)
diff --git a/src/include/units/isq/natural/bits/dimensions.h b/src/systems/isq-natural/include/units/isq/natural/bits/dimensions.h
similarity index 100%
rename from src/include/units/isq/natural/bits/dimensions.h
rename to src/systems/isq-natural/include/units/isq/natural/bits/dimensions.h
diff --git a/src/include/units/isq/natural/bits/units.h b/src/systems/isq-natural/include/units/isq/natural/bits/units.h
similarity index 100%
rename from src/include/units/isq/natural/bits/units.h
rename to src/systems/isq-natural/include/units/isq/natural/bits/units.h
diff --git a/src/include/units/isq/natural/constants.h b/src/systems/isq-natural/include/units/isq/natural/constants.h
similarity index 100%
rename from src/include/units/isq/natural/constants.h
rename to src/systems/isq-natural/include/units/isq/natural/constants.h
diff --git a/src/include/units/isq/natural/natural.h b/src/systems/isq-natural/include/units/isq/natural/natural.h
similarity index 100%
rename from src/include/units/isq/natural/natural.h
rename to src/systems/isq-natural/include/units/isq/natural/natural.h
diff --git a/src/systems/isq/CMakeLists.txt b/src/systems/isq/CMakeLists.txt
new file mode 100644
index 00000000..2394315d
--- /dev/null
+++ b/src/systems/isq/CMakeLists.txt
@@ -0,0 +1,25 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+add_system(isq mp-units::core)
diff --git a/src/include/units/isq/dimensions.h b/src/systems/isq/include/units/isq/dimensions.h
similarity index 100%
rename from src/include/units/isq/dimensions.h
rename to src/systems/isq/include/units/isq/dimensions.h
diff --git a/src/include/units/isq/dimensions/absorbed_dose.h b/src/systems/isq/include/units/isq/dimensions/absorbed_dose.h
similarity index 100%
rename from src/include/units/isq/dimensions/absorbed_dose.h
rename to src/systems/isq/include/units/isq/dimensions/absorbed_dose.h
diff --git a/src/include/units/isq/dimensions/acceleration.h b/src/systems/isq/include/units/isq/dimensions/acceleration.h
similarity index 100%
rename from src/include/units/isq/dimensions/acceleration.h
rename to src/systems/isq/include/units/isq/dimensions/acceleration.h
diff --git a/src/include/units/isq/dimensions/amount_of_substance.h b/src/systems/isq/include/units/isq/dimensions/amount_of_substance.h
similarity index 100%
rename from src/include/units/isq/dimensions/amount_of_substance.h
rename to src/systems/isq/include/units/isq/dimensions/amount_of_substance.h
diff --git a/src/include/units/isq/dimensions/angular_velocity.h b/src/systems/isq/include/units/isq/dimensions/angular_velocity.h
similarity index 100%
rename from src/include/units/isq/dimensions/angular_velocity.h
rename to src/systems/isq/include/units/isq/dimensions/angular_velocity.h
diff --git a/src/include/units/isq/dimensions/area.h b/src/systems/isq/include/units/isq/dimensions/area.h
similarity index 100%
rename from src/include/units/isq/dimensions/area.h
rename to src/systems/isq/include/units/isq/dimensions/area.h
diff --git a/src/include/units/isq/dimensions/capacitance.h b/src/systems/isq/include/units/isq/dimensions/capacitance.h
similarity index 100%
rename from src/include/units/isq/dimensions/capacitance.h
rename to src/systems/isq/include/units/isq/dimensions/capacitance.h
diff --git a/src/include/units/isq/dimensions/catalytic_activity.h b/src/systems/isq/include/units/isq/dimensions/catalytic_activity.h
similarity index 100%
rename from src/include/units/isq/dimensions/catalytic_activity.h
rename to src/systems/isq/include/units/isq/dimensions/catalytic_activity.h
diff --git a/src/include/units/isq/dimensions/charge_density.h b/src/systems/isq/include/units/isq/dimensions/charge_density.h
similarity index 100%
rename from src/include/units/isq/dimensions/charge_density.h
rename to src/systems/isq/include/units/isq/dimensions/charge_density.h
diff --git a/src/include/units/isq/dimensions/concentration.h b/src/systems/isq/include/units/isq/dimensions/concentration.h
similarity index 100%
rename from src/include/units/isq/dimensions/concentration.h
rename to src/systems/isq/include/units/isq/dimensions/concentration.h
diff --git a/src/include/units/isq/dimensions/conductance.h b/src/systems/isq/include/units/isq/dimensions/conductance.h
similarity index 100%
rename from src/include/units/isq/dimensions/conductance.h
rename to src/systems/isq/include/units/isq/dimensions/conductance.h
diff --git a/src/include/units/isq/dimensions/current_density.h b/src/systems/isq/include/units/isq/dimensions/current_density.h
similarity index 100%
rename from src/include/units/isq/dimensions/current_density.h
rename to src/systems/isq/include/units/isq/dimensions/current_density.h
diff --git a/src/include/units/isq/dimensions/density.h b/src/systems/isq/include/units/isq/dimensions/density.h
similarity index 100%
rename from src/include/units/isq/dimensions/density.h
rename to src/systems/isq/include/units/isq/dimensions/density.h
diff --git a/src/include/units/isq/dimensions/dynamic_viscosity.h b/src/systems/isq/include/units/isq/dimensions/dynamic_viscosity.h
similarity index 100%
rename from src/include/units/isq/dimensions/dynamic_viscosity.h
rename to src/systems/isq/include/units/isq/dimensions/dynamic_viscosity.h
diff --git a/src/include/units/isq/dimensions/electric_charge.h b/src/systems/isq/include/units/isq/dimensions/electric_charge.h
similarity index 100%
rename from src/include/units/isq/dimensions/electric_charge.h
rename to src/systems/isq/include/units/isq/dimensions/electric_charge.h
diff --git a/src/include/units/isq/dimensions/electric_current.h b/src/systems/isq/include/units/isq/dimensions/electric_current.h
similarity index 100%
rename from src/include/units/isq/dimensions/electric_current.h
rename to src/systems/isq/include/units/isq/dimensions/electric_current.h
diff --git a/src/include/units/isq/dimensions/electric_field_strength.h b/src/systems/isq/include/units/isq/dimensions/electric_field_strength.h
similarity index 100%
rename from src/include/units/isq/dimensions/electric_field_strength.h
rename to src/systems/isq/include/units/isq/dimensions/electric_field_strength.h
diff --git a/src/include/units/isq/dimensions/energy.h b/src/systems/isq/include/units/isq/dimensions/energy.h
similarity index 100%
rename from src/include/units/isq/dimensions/energy.h
rename to src/systems/isq/include/units/isq/dimensions/energy.h
diff --git a/src/include/units/isq/dimensions/energy_density.h b/src/systems/isq/include/units/isq/dimensions/energy_density.h
similarity index 100%
rename from src/include/units/isq/dimensions/energy_density.h
rename to src/systems/isq/include/units/isq/dimensions/energy_density.h
diff --git a/src/include/units/isq/dimensions/force.h b/src/systems/isq/include/units/isq/dimensions/force.h
similarity index 100%
rename from src/include/units/isq/dimensions/force.h
rename to src/systems/isq/include/units/isq/dimensions/force.h
diff --git a/src/include/units/isq/dimensions/frequency.h b/src/systems/isq/include/units/isq/dimensions/frequency.h
similarity index 100%
rename from src/include/units/isq/dimensions/frequency.h
rename to src/systems/isq/include/units/isq/dimensions/frequency.h
diff --git a/src/include/units/isq/dimensions/heat_capacity.h b/src/systems/isq/include/units/isq/dimensions/heat_capacity.h
similarity index 100%
rename from src/include/units/isq/dimensions/heat_capacity.h
rename to src/systems/isq/include/units/isq/dimensions/heat_capacity.h
diff --git a/src/include/units/isq/dimensions/inductance.h b/src/systems/isq/include/units/isq/dimensions/inductance.h
similarity index 100%
rename from src/include/units/isq/dimensions/inductance.h
rename to src/systems/isq/include/units/isq/dimensions/inductance.h
diff --git a/src/include/units/isq/dimensions/length.h b/src/systems/isq/include/units/isq/dimensions/length.h
similarity index 100%
rename from src/include/units/isq/dimensions/length.h
rename to src/systems/isq/include/units/isq/dimensions/length.h
diff --git a/src/include/units/isq/dimensions/luminance.h b/src/systems/isq/include/units/isq/dimensions/luminance.h
similarity index 100%
rename from src/include/units/isq/dimensions/luminance.h
rename to src/systems/isq/include/units/isq/dimensions/luminance.h
diff --git a/src/include/units/isq/dimensions/luminous_intensity.h b/src/systems/isq/include/units/isq/dimensions/luminous_intensity.h
similarity index 100%
rename from src/include/units/isq/dimensions/luminous_intensity.h
rename to src/systems/isq/include/units/isq/dimensions/luminous_intensity.h
diff --git a/src/include/units/isq/dimensions/magnetic_flux.h b/src/systems/isq/include/units/isq/dimensions/magnetic_flux.h
similarity index 100%
rename from src/include/units/isq/dimensions/magnetic_flux.h
rename to src/systems/isq/include/units/isq/dimensions/magnetic_flux.h
diff --git a/src/include/units/isq/dimensions/magnetic_induction.h b/src/systems/isq/include/units/isq/dimensions/magnetic_induction.h
similarity index 100%
rename from src/include/units/isq/dimensions/magnetic_induction.h
rename to src/systems/isq/include/units/isq/dimensions/magnetic_induction.h
diff --git a/src/include/units/isq/dimensions/mass.h b/src/systems/isq/include/units/isq/dimensions/mass.h
similarity index 100%
rename from src/include/units/isq/dimensions/mass.h
rename to src/systems/isq/include/units/isq/dimensions/mass.h
diff --git a/src/include/units/isq/dimensions/molar_energy.h b/src/systems/isq/include/units/isq/dimensions/molar_energy.h
similarity index 100%
rename from src/include/units/isq/dimensions/molar_energy.h
rename to src/systems/isq/include/units/isq/dimensions/molar_energy.h
diff --git a/src/include/units/isq/dimensions/momentum.h b/src/systems/isq/include/units/isq/dimensions/momentum.h
similarity index 100%
rename from src/include/units/isq/dimensions/momentum.h
rename to src/systems/isq/include/units/isq/dimensions/momentum.h
diff --git a/src/include/units/isq/dimensions/permeability.h b/src/systems/isq/include/units/isq/dimensions/permeability.h
similarity index 100%
rename from src/include/units/isq/dimensions/permeability.h
rename to src/systems/isq/include/units/isq/dimensions/permeability.h
diff --git a/src/include/units/isq/dimensions/permittivity.h b/src/systems/isq/include/units/isq/dimensions/permittivity.h
similarity index 100%
rename from src/include/units/isq/dimensions/permittivity.h
rename to src/systems/isq/include/units/isq/dimensions/permittivity.h
diff --git a/src/include/units/isq/dimensions/power.h b/src/systems/isq/include/units/isq/dimensions/power.h
similarity index 100%
rename from src/include/units/isq/dimensions/power.h
rename to src/systems/isq/include/units/isq/dimensions/power.h
diff --git a/src/include/units/isq/dimensions/pressure.h b/src/systems/isq/include/units/isq/dimensions/pressure.h
similarity index 100%
rename from src/include/units/isq/dimensions/pressure.h
rename to src/systems/isq/include/units/isq/dimensions/pressure.h
diff --git a/src/include/units/isq/dimensions/radioactivity.h b/src/systems/isq/include/units/isq/dimensions/radioactivity.h
similarity index 100%
rename from src/include/units/isq/dimensions/radioactivity.h
rename to src/systems/isq/include/units/isq/dimensions/radioactivity.h
diff --git a/src/include/units/isq/dimensions/resistance.h b/src/systems/isq/include/units/isq/dimensions/resistance.h
similarity index 100%
rename from src/include/units/isq/dimensions/resistance.h
rename to src/systems/isq/include/units/isq/dimensions/resistance.h
diff --git a/src/include/units/isq/dimensions/speed.h b/src/systems/isq/include/units/isq/dimensions/speed.h
similarity index 100%
rename from src/include/units/isq/dimensions/speed.h
rename to src/systems/isq/include/units/isq/dimensions/speed.h
diff --git a/src/include/units/isq/dimensions/surface_tension.h b/src/systems/isq/include/units/isq/dimensions/surface_tension.h
similarity index 100%
rename from src/include/units/isq/dimensions/surface_tension.h
rename to src/systems/isq/include/units/isq/dimensions/surface_tension.h
diff --git a/src/include/units/isq/dimensions/thermal_conductivity.h b/src/systems/isq/include/units/isq/dimensions/thermal_conductivity.h
similarity index 100%
rename from src/include/units/isq/dimensions/thermal_conductivity.h
rename to src/systems/isq/include/units/isq/dimensions/thermal_conductivity.h
diff --git a/src/include/units/isq/dimensions/thermodynamic_temperature.h b/src/systems/isq/include/units/isq/dimensions/thermodynamic_temperature.h
similarity index 100%
rename from src/include/units/isq/dimensions/thermodynamic_temperature.h
rename to src/systems/isq/include/units/isq/dimensions/thermodynamic_temperature.h
diff --git a/src/include/units/isq/dimensions/time.h b/src/systems/isq/include/units/isq/dimensions/time.h
similarity index 100%
rename from src/include/units/isq/dimensions/time.h
rename to src/systems/isq/include/units/isq/dimensions/time.h
diff --git a/src/include/units/isq/dimensions/torque.h b/src/systems/isq/include/units/isq/dimensions/torque.h
similarity index 100%
rename from src/include/units/isq/dimensions/torque.h
rename to src/systems/isq/include/units/isq/dimensions/torque.h
diff --git a/src/include/units/isq/dimensions/voltage.h b/src/systems/isq/include/units/isq/dimensions/voltage.h
similarity index 100%
rename from src/include/units/isq/dimensions/voltage.h
rename to src/systems/isq/include/units/isq/dimensions/voltage.h
diff --git a/src/include/units/isq/dimensions/volume.h b/src/systems/isq/include/units/isq/dimensions/volume.h
similarity index 100%
rename from src/include/units/isq/dimensions/volume.h
rename to src/systems/isq/include/units/isq/dimensions/volume.h
diff --git a/src/systems/si-cgs/CMakeLists.txt b/src/systems/si-cgs/CMakeLists.txt
new file mode 100644
index 00000000..a2bb7755
--- /dev/null
+++ b/src/systems/si-cgs/CMakeLists.txt
@@ -0,0 +1,25 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+add_system(si-cgs mp-units::si)
diff --git a/src/include/units/isq/si/cgs/acceleration.h b/src/systems/si-cgs/include/units/isq/si/cgs/acceleration.h
similarity index 100%
rename from src/include/units/isq/si/cgs/acceleration.h
rename to src/systems/si-cgs/include/units/isq/si/cgs/acceleration.h
diff --git a/src/include/units/isq/si/cgs/area.h b/src/systems/si-cgs/include/units/isq/si/cgs/area.h
similarity index 100%
rename from src/include/units/isq/si/cgs/area.h
rename to src/systems/si-cgs/include/units/isq/si/cgs/area.h
diff --git a/src/include/units/isq/si/cgs/cgs.h b/src/systems/si-cgs/include/units/isq/si/cgs/cgs.h
similarity index 100%
rename from src/include/units/isq/si/cgs/cgs.h
rename to src/systems/si-cgs/include/units/isq/si/cgs/cgs.h
diff --git a/src/include/units/isq/si/cgs/energy.h b/src/systems/si-cgs/include/units/isq/si/cgs/energy.h
similarity index 100%
rename from src/include/units/isq/si/cgs/energy.h
rename to src/systems/si-cgs/include/units/isq/si/cgs/energy.h
diff --git a/src/include/units/isq/si/cgs/force.h b/src/systems/si-cgs/include/units/isq/si/cgs/force.h
similarity index 100%
rename from src/include/units/isq/si/cgs/force.h
rename to src/systems/si-cgs/include/units/isq/si/cgs/force.h
diff --git a/src/include/units/isq/si/cgs/length.h b/src/systems/si-cgs/include/units/isq/si/cgs/length.h
similarity index 100%
rename from src/include/units/isq/si/cgs/length.h
rename to src/systems/si-cgs/include/units/isq/si/cgs/length.h
diff --git a/src/include/units/isq/si/cgs/mass.h b/src/systems/si-cgs/include/units/isq/si/cgs/mass.h
similarity index 100%
rename from src/include/units/isq/si/cgs/mass.h
rename to src/systems/si-cgs/include/units/isq/si/cgs/mass.h
diff --git a/src/include/units/isq/si/cgs/power.h b/src/systems/si-cgs/include/units/isq/si/cgs/power.h
similarity index 100%
rename from src/include/units/isq/si/cgs/power.h
rename to src/systems/si-cgs/include/units/isq/si/cgs/power.h
diff --git a/src/include/units/isq/si/cgs/pressure.h b/src/systems/si-cgs/include/units/isq/si/cgs/pressure.h
similarity index 100%
rename from src/include/units/isq/si/cgs/pressure.h
rename to src/systems/si-cgs/include/units/isq/si/cgs/pressure.h
diff --git a/src/include/units/isq/si/cgs/speed.h b/src/systems/si-cgs/include/units/isq/si/cgs/speed.h
similarity index 100%
rename from src/include/units/isq/si/cgs/speed.h
rename to src/systems/si-cgs/include/units/isq/si/cgs/speed.h
diff --git a/src/include/units/isq/si/cgs/time.h b/src/systems/si-cgs/include/units/isq/si/cgs/time.h
similarity index 100%
rename from src/include/units/isq/si/cgs/time.h
rename to src/systems/si-cgs/include/units/isq/si/cgs/time.h
diff --git a/src/systems/si-fps/CMakeLists.txt b/src/systems/si-fps/CMakeLists.txt
new file mode 100644
index 00000000..16106a5d
--- /dev/null
+++ b/src/systems/si-fps/CMakeLists.txt
@@ -0,0 +1,25 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+add_system(si-fps mp-units::si)
diff --git a/src/include/units/isq/si/fps/acceleration.h b/src/systems/si-fps/include/units/isq/si/fps/acceleration.h
similarity index 100%
rename from src/include/units/isq/si/fps/acceleration.h
rename to src/systems/si-fps/include/units/isq/si/fps/acceleration.h
diff --git a/src/include/units/isq/si/fps/area.h b/src/systems/si-fps/include/units/isq/si/fps/area.h
similarity index 100%
rename from src/include/units/isq/si/fps/area.h
rename to src/systems/si-fps/include/units/isq/si/fps/area.h
diff --git a/src/include/units/isq/si/fps/density.h b/src/systems/si-fps/include/units/isq/si/fps/density.h
similarity index 100%
rename from src/include/units/isq/si/fps/density.h
rename to src/systems/si-fps/include/units/isq/si/fps/density.h
diff --git a/src/include/units/isq/si/fps/energy.h b/src/systems/si-fps/include/units/isq/si/fps/energy.h
similarity index 100%
rename from src/include/units/isq/si/fps/energy.h
rename to src/systems/si-fps/include/units/isq/si/fps/energy.h
diff --git a/src/include/units/isq/si/fps/force.h b/src/systems/si-fps/include/units/isq/si/fps/force.h
similarity index 100%
rename from src/include/units/isq/si/fps/force.h
rename to src/systems/si-fps/include/units/isq/si/fps/force.h
diff --git a/src/include/units/isq/si/fps/fps.h b/src/systems/si-fps/include/units/isq/si/fps/fps.h
similarity index 100%
rename from src/include/units/isq/si/fps/fps.h
rename to src/systems/si-fps/include/units/isq/si/fps/fps.h
diff --git a/src/include/units/isq/si/fps/length.h b/src/systems/si-fps/include/units/isq/si/fps/length.h
similarity index 100%
rename from src/include/units/isq/si/fps/length.h
rename to src/systems/si-fps/include/units/isq/si/fps/length.h
diff --git a/src/include/units/isq/si/fps/mass.h b/src/systems/si-fps/include/units/isq/si/fps/mass.h
similarity index 100%
rename from src/include/units/isq/si/fps/mass.h
rename to src/systems/si-fps/include/units/isq/si/fps/mass.h
diff --git a/src/include/units/isq/si/fps/power.h b/src/systems/si-fps/include/units/isq/si/fps/power.h
similarity index 100%
rename from src/include/units/isq/si/fps/power.h
rename to src/systems/si-fps/include/units/isq/si/fps/power.h
diff --git a/src/include/units/isq/si/fps/pressure.h b/src/systems/si-fps/include/units/isq/si/fps/pressure.h
similarity index 100%
rename from src/include/units/isq/si/fps/pressure.h
rename to src/systems/si-fps/include/units/isq/si/fps/pressure.h
diff --git a/src/include/units/isq/si/fps/speed.h b/src/systems/si-fps/include/units/isq/si/fps/speed.h
similarity index 100%
rename from src/include/units/isq/si/fps/speed.h
rename to src/systems/si-fps/include/units/isq/si/fps/speed.h
diff --git a/src/include/units/isq/si/fps/time.h b/src/systems/si-fps/include/units/isq/si/fps/time.h
similarity index 100%
rename from src/include/units/isq/si/fps/time.h
rename to src/systems/si-fps/include/units/isq/si/fps/time.h
diff --git a/src/include/units/isq/si/fps/volume.h b/src/systems/si-fps/include/units/isq/si/fps/volume.h
similarity index 100%
rename from src/include/units/isq/si/fps/volume.h
rename to src/systems/si-fps/include/units/isq/si/fps/volume.h
diff --git a/src/systems/si-iau/CMakeLists.txt b/src/systems/si-iau/CMakeLists.txt
new file mode 100644
index 00000000..ee40346f
--- /dev/null
+++ b/src/systems/si-iau/CMakeLists.txt
@@ -0,0 +1,25 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+add_system(si-iau mp-units::si)
diff --git a/src/include/units/isq/si/iau/iau.h b/src/systems/si-iau/include/units/isq/si/iau/iau.h
similarity index 100%
rename from src/include/units/isq/si/iau/iau.h
rename to src/systems/si-iau/include/units/isq/si/iau/iau.h
diff --git a/src/include/units/isq/si/iau/length.h b/src/systems/si-iau/include/units/isq/si/iau/length.h
similarity index 100%
rename from src/include/units/isq/si/iau/length.h
rename to src/systems/si-iau/include/units/isq/si/iau/length.h
diff --git a/src/systems/si-imperial/CMakeLists.txt b/src/systems/si-imperial/CMakeLists.txt
new file mode 100644
index 00000000..477365a1
--- /dev/null
+++ b/src/systems/si-imperial/CMakeLists.txt
@@ -0,0 +1,25 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+add_system(si-imperial mp-units::si)
diff --git a/src/include/units/isq/si/imperial/imperial.h b/src/systems/si-imperial/include/units/isq/si/imperial/imperial.h
similarity index 100%
rename from src/include/units/isq/si/imperial/imperial.h
rename to src/systems/si-imperial/include/units/isq/si/imperial/imperial.h
diff --git a/src/include/units/isq/si/imperial/length.h b/src/systems/si-imperial/include/units/isq/si/imperial/length.h
similarity index 100%
rename from src/include/units/isq/si/imperial/length.h
rename to src/systems/si-imperial/include/units/isq/si/imperial/length.h
diff --git a/src/systems/si-international/CMakeLists.txt b/src/systems/si-international/CMakeLists.txt
new file mode 100644
index 00000000..779e97cc
--- /dev/null
+++ b/src/systems/si-international/CMakeLists.txt
@@ -0,0 +1,25 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+add_system(si-international mp-units::si)
diff --git a/src/include/units/isq/si/international/area.h b/src/systems/si-international/include/units/isq/si/international/area.h
similarity index 100%
rename from src/include/units/isq/si/international/area.h
rename to src/systems/si-international/include/units/isq/si/international/area.h
diff --git a/src/include/units/isq/si/international/international.h b/src/systems/si-international/include/units/isq/si/international/international.h
similarity index 100%
rename from src/include/units/isq/si/international/international.h
rename to src/systems/si-international/include/units/isq/si/international/international.h
diff --git a/src/include/units/isq/si/international/length.h b/src/systems/si-international/include/units/isq/si/international/length.h
similarity index 100%
rename from src/include/units/isq/si/international/length.h
rename to src/systems/si-international/include/units/isq/si/international/length.h
diff --git a/src/include/units/isq/si/international/speed.h b/src/systems/si-international/include/units/isq/si/international/speed.h
similarity index 100%
rename from src/include/units/isq/si/international/speed.h
rename to src/systems/si-international/include/units/isq/si/international/speed.h
diff --git a/src/include/units/isq/si/international/volume.h b/src/systems/si-international/include/units/isq/si/international/volume.h
similarity index 100%
rename from src/include/units/isq/si/international/volume.h
rename to src/systems/si-international/include/units/isq/si/international/volume.h
diff --git a/src/systems/si-typographic/CMakeLists.txt b/src/systems/si-typographic/CMakeLists.txt
new file mode 100644
index 00000000..96dd63ae
--- /dev/null
+++ b/src/systems/si-typographic/CMakeLists.txt
@@ -0,0 +1,25 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+add_system(si-typographic mp-units::si)
diff --git a/src/include/units/isq/si/typographic/length.h b/src/systems/si-typographic/include/units/isq/si/typographic/length.h
similarity index 100%
rename from src/include/units/isq/si/typographic/length.h
rename to src/systems/si-typographic/include/units/isq/si/typographic/length.h
diff --git a/src/include/units/isq/si/typographic/typographic.h b/src/systems/si-typographic/include/units/isq/si/typographic/typographic.h
similarity index 100%
rename from src/include/units/isq/si/typographic/typographic.h
rename to src/systems/si-typographic/include/units/isq/si/typographic/typographic.h
diff --git a/src/systems/si-us/CMakeLists.txt b/src/systems/si-us/CMakeLists.txt
new file mode 100644
index 00000000..e6a25e6a
--- /dev/null
+++ b/src/systems/si-us/CMakeLists.txt
@@ -0,0 +1,25 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+add_system(si-us mp-units::si)
diff --git a/src/include/units/isq/si/us/length.h b/src/systems/si-us/include/units/isq/si/us/length.h
similarity index 100%
rename from src/include/units/isq/si/us/length.h
rename to src/systems/si-us/include/units/isq/si/us/length.h
diff --git a/src/include/units/isq/si/us/us.h b/src/systems/si-us/include/units/isq/si/us/us.h
similarity index 100%
rename from src/include/units/isq/si/us/us.h
rename to src/systems/si-us/include/units/isq/si/us/us.h
diff --git a/src/systems/si/CMakeLists.txt b/src/systems/si/CMakeLists.txt
new file mode 100644
index 00000000..7994bd13
--- /dev/null
+++ b/src/systems/si/CMakeLists.txt
@@ -0,0 +1,25 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Mateusz Pusz
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+cmake_minimum_required(VERSION 3.15)
+
+add_system(si mp-units::isq)
diff --git a/src/include/units/isq/si/absorbed_dose.h b/src/systems/si/include/units/isq/si/absorbed_dose.h
similarity index 100%
rename from src/include/units/isq/si/absorbed_dose.h
rename to src/systems/si/include/units/isq/si/absorbed_dose.h
diff --git a/src/include/units/isq/si/acceleration.h b/src/systems/si/include/units/isq/si/acceleration.h
similarity index 100%
rename from src/include/units/isq/si/acceleration.h
rename to src/systems/si/include/units/isq/si/acceleration.h
diff --git a/src/include/units/isq/si/amount_of_substance.h b/src/systems/si/include/units/isq/si/amount_of_substance.h
similarity index 100%
rename from src/include/units/isq/si/amount_of_substance.h
rename to src/systems/si/include/units/isq/si/amount_of_substance.h
diff --git a/src/include/units/isq/si/angular_velocity.h b/src/systems/si/include/units/isq/si/angular_velocity.h
similarity index 100%
rename from src/include/units/isq/si/angular_velocity.h
rename to src/systems/si/include/units/isq/si/angular_velocity.h
diff --git a/src/include/units/isq/si/area.h b/src/systems/si/include/units/isq/si/area.h
similarity index 100%
rename from src/include/units/isq/si/area.h
rename to src/systems/si/include/units/isq/si/area.h
diff --git a/src/include/units/isq/si/capacitance.h b/src/systems/si/include/units/isq/si/capacitance.h
similarity index 100%
rename from src/include/units/isq/si/capacitance.h
rename to src/systems/si/include/units/isq/si/capacitance.h
diff --git a/src/include/units/isq/si/catalytic_activity.h b/src/systems/si/include/units/isq/si/catalytic_activity.h
similarity index 100%
rename from src/include/units/isq/si/catalytic_activity.h
rename to src/systems/si/include/units/isq/si/catalytic_activity.h
diff --git a/src/include/units/isq/si/charge_density.h b/src/systems/si/include/units/isq/si/charge_density.h
similarity index 100%
rename from src/include/units/isq/si/charge_density.h
rename to src/systems/si/include/units/isq/si/charge_density.h
diff --git a/src/include/units/isq/si/concentration.h b/src/systems/si/include/units/isq/si/concentration.h
similarity index 100%
rename from src/include/units/isq/si/concentration.h
rename to src/systems/si/include/units/isq/si/concentration.h
diff --git a/src/include/units/isq/si/conductance.h b/src/systems/si/include/units/isq/si/conductance.h
similarity index 100%
rename from src/include/units/isq/si/conductance.h
rename to src/systems/si/include/units/isq/si/conductance.h
diff --git a/src/include/units/isq/si/constants.h b/src/systems/si/include/units/isq/si/constants.h
similarity index 100%
rename from src/include/units/isq/si/constants.h
rename to src/systems/si/include/units/isq/si/constants.h
diff --git a/src/include/units/isq/si/current_density.h b/src/systems/si/include/units/isq/si/current_density.h
similarity index 100%
rename from src/include/units/isq/si/current_density.h
rename to src/systems/si/include/units/isq/si/current_density.h
diff --git a/src/include/units/isq/si/density.h b/src/systems/si/include/units/isq/si/density.h
similarity index 100%
rename from src/include/units/isq/si/density.h
rename to src/systems/si/include/units/isq/si/density.h
diff --git a/src/include/units/isq/si/dynamic_viscosity.h b/src/systems/si/include/units/isq/si/dynamic_viscosity.h
similarity index 100%
rename from src/include/units/isq/si/dynamic_viscosity.h
rename to src/systems/si/include/units/isq/si/dynamic_viscosity.h
diff --git a/src/include/units/isq/si/electric_charge.h b/src/systems/si/include/units/isq/si/electric_charge.h
similarity index 100%
rename from src/include/units/isq/si/electric_charge.h
rename to src/systems/si/include/units/isq/si/electric_charge.h
diff --git a/src/include/units/isq/si/electric_current.h b/src/systems/si/include/units/isq/si/electric_current.h
similarity index 100%
rename from src/include/units/isq/si/electric_current.h
rename to src/systems/si/include/units/isq/si/electric_current.h
diff --git a/src/include/units/isq/si/electric_field_strength.h b/src/systems/si/include/units/isq/si/electric_field_strength.h
similarity index 100%
rename from src/include/units/isq/si/electric_field_strength.h
rename to src/systems/si/include/units/isq/si/electric_field_strength.h
diff --git a/src/include/units/isq/si/energy.h b/src/systems/si/include/units/isq/si/energy.h
similarity index 100%
rename from src/include/units/isq/si/energy.h
rename to src/systems/si/include/units/isq/si/energy.h
diff --git a/src/include/units/isq/si/energy_density.h b/src/systems/si/include/units/isq/si/energy_density.h
similarity index 100%
rename from src/include/units/isq/si/energy_density.h
rename to src/systems/si/include/units/isq/si/energy_density.h
diff --git a/src/include/units/isq/si/force.h b/src/systems/si/include/units/isq/si/force.h
similarity index 100%
rename from src/include/units/isq/si/force.h
rename to src/systems/si/include/units/isq/si/force.h
diff --git a/src/include/units/isq/si/frequency.h b/src/systems/si/include/units/isq/si/frequency.h
similarity index 100%
rename from src/include/units/isq/si/frequency.h
rename to src/systems/si/include/units/isq/si/frequency.h
diff --git a/src/include/units/isq/si/heat_capacity.h b/src/systems/si/include/units/isq/si/heat_capacity.h
similarity index 100%
rename from src/include/units/isq/si/heat_capacity.h
rename to src/systems/si/include/units/isq/si/heat_capacity.h
diff --git a/src/include/units/isq/si/inductance.h b/src/systems/si/include/units/isq/si/inductance.h
similarity index 100%
rename from src/include/units/isq/si/inductance.h
rename to src/systems/si/include/units/isq/si/inductance.h
diff --git a/src/include/units/isq/si/length.h b/src/systems/si/include/units/isq/si/length.h
similarity index 100%
rename from src/include/units/isq/si/length.h
rename to src/systems/si/include/units/isq/si/length.h
diff --git a/src/include/units/isq/si/luminance.h b/src/systems/si/include/units/isq/si/luminance.h
similarity index 100%
rename from src/include/units/isq/si/luminance.h
rename to src/systems/si/include/units/isq/si/luminance.h
diff --git a/src/include/units/isq/si/luminous_intensity.h b/src/systems/si/include/units/isq/si/luminous_intensity.h
similarity index 100%
rename from src/include/units/isq/si/luminous_intensity.h
rename to src/systems/si/include/units/isq/si/luminous_intensity.h
diff --git a/src/include/units/isq/si/magnetic_flux.h b/src/systems/si/include/units/isq/si/magnetic_flux.h
similarity index 100%
rename from src/include/units/isq/si/magnetic_flux.h
rename to src/systems/si/include/units/isq/si/magnetic_flux.h
diff --git a/src/include/units/isq/si/magnetic_induction.h b/src/systems/si/include/units/isq/si/magnetic_induction.h
similarity index 100%
rename from src/include/units/isq/si/magnetic_induction.h
rename to src/systems/si/include/units/isq/si/magnetic_induction.h
diff --git a/src/include/units/isq/si/mass.h b/src/systems/si/include/units/isq/si/mass.h
similarity index 100%
rename from src/include/units/isq/si/mass.h
rename to src/systems/si/include/units/isq/si/mass.h
diff --git a/src/include/units/isq/si/molar_energy.h b/src/systems/si/include/units/isq/si/molar_energy.h
similarity index 100%
rename from src/include/units/isq/si/molar_energy.h
rename to src/systems/si/include/units/isq/si/molar_energy.h
diff --git a/src/include/units/isq/si/momentum.h b/src/systems/si/include/units/isq/si/momentum.h
similarity index 100%
rename from src/include/units/isq/si/momentum.h
rename to src/systems/si/include/units/isq/si/momentum.h
diff --git a/src/include/units/isq/si/permeability.h b/src/systems/si/include/units/isq/si/permeability.h
similarity index 100%
rename from src/include/units/isq/si/permeability.h
rename to src/systems/si/include/units/isq/si/permeability.h
diff --git a/src/include/units/isq/si/permittivity.h b/src/systems/si/include/units/isq/si/permittivity.h
similarity index 100%
rename from src/include/units/isq/si/permittivity.h
rename to src/systems/si/include/units/isq/si/permittivity.h
diff --git a/src/include/units/isq/si/power.h b/src/systems/si/include/units/isq/si/power.h
similarity index 100%
rename from src/include/units/isq/si/power.h
rename to src/systems/si/include/units/isq/si/power.h
diff --git a/src/include/units/isq/si/prefixes.h b/src/systems/si/include/units/isq/si/prefixes.h
similarity index 100%
rename from src/include/units/isq/si/prefixes.h
rename to src/systems/si/include/units/isq/si/prefixes.h
diff --git a/src/include/units/isq/si/pressure.h b/src/systems/si/include/units/isq/si/pressure.h
similarity index 100%
rename from src/include/units/isq/si/pressure.h
rename to src/systems/si/include/units/isq/si/pressure.h
diff --git a/src/include/units/isq/si/radioactivity.h b/src/systems/si/include/units/isq/si/radioactivity.h
similarity index 100%
rename from src/include/units/isq/si/radioactivity.h
rename to src/systems/si/include/units/isq/si/radioactivity.h
diff --git a/src/include/units/isq/si/resistance.h b/src/systems/si/include/units/isq/si/resistance.h
similarity index 100%
rename from src/include/units/isq/si/resistance.h
rename to src/systems/si/include/units/isq/si/resistance.h
diff --git a/src/include/units/isq/si/si.h b/src/systems/si/include/units/isq/si/si.h
similarity index 100%
rename from src/include/units/isq/si/si.h
rename to src/systems/si/include/units/isq/si/si.h
diff --git a/src/include/units/isq/si/speed.h b/src/systems/si/include/units/isq/si/speed.h
similarity index 100%
rename from src/include/units/isq/si/speed.h
rename to src/systems/si/include/units/isq/si/speed.h
diff --git a/src/include/units/isq/si/surface_tension.h b/src/systems/si/include/units/isq/si/surface_tension.h
similarity index 100%
rename from src/include/units/isq/si/surface_tension.h
rename to src/systems/si/include/units/isq/si/surface_tension.h
diff --git a/src/include/units/isq/si/thermal_conductivity.h b/src/systems/si/include/units/isq/si/thermal_conductivity.h
similarity index 100%
rename from src/include/units/isq/si/thermal_conductivity.h
rename to src/systems/si/include/units/isq/si/thermal_conductivity.h
diff --git a/src/include/units/isq/si/thermodynamic_temperature.h b/src/systems/si/include/units/isq/si/thermodynamic_temperature.h
similarity index 100%
rename from src/include/units/isq/si/thermodynamic_temperature.h
rename to src/systems/si/include/units/isq/si/thermodynamic_temperature.h
diff --git a/src/include/units/isq/si/time.h b/src/systems/si/include/units/isq/si/time.h
similarity index 100%
rename from src/include/units/isq/si/time.h
rename to src/systems/si/include/units/isq/si/time.h
diff --git a/src/include/units/isq/si/torque.h b/src/systems/si/include/units/isq/si/torque.h
similarity index 100%
rename from src/include/units/isq/si/torque.h
rename to src/systems/si/include/units/isq/si/torque.h
diff --git a/src/include/units/isq/si/voltage.h b/src/systems/si/include/units/isq/si/voltage.h
similarity index 100%
rename from src/include/units/isq/si/voltage.h
rename to src/systems/si/include/units/isq/si/voltage.h
diff --git a/src/include/units/isq/si/volume.h b/src/systems/si/include/units/isq/si/volume.h
similarity index 100%
rename from src/include/units/isq/si/volume.h
rename to src/systems/si/include/units/isq/si/volume.h
diff --git a/test/unit_test/runtime/CMakeLists.txt b/test/unit_test/runtime/CMakeLists.txt
index eda86a20..7610b9fc 100644
--- a/test/unit_test/runtime/CMakeLists.txt
+++ b/test/unit_test/runtime/CMakeLists.txt
@@ -32,16 +32,14 @@ add_executable(unit_tests_runtime
     fmt_units_test.cpp
     distribution_test.cpp
 )
-target_link_libraries(unit_tests_runtime
-    PRIVATE
-        mp-units::mp-units
-        Catch2::Catch2
+target_link_libraries(unit_tests_runtime PRIVATE
+    mp-units::mp-units
+    Catch2::Catch2
 )
 
 if(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
-    target_compile_options(unit_tests_runtime
-        PRIVATE
-            /wd4244 # 'conversion' conversion from 'type1' to 'type2', possible loss of data
+    target_compile_options(unit_tests_runtime PRIVATE
+        /wd4244 # 'conversion' conversion from 'type1' to 'type2', possible loss of data
     )
 endif()
 
diff --git a/test/unit_test/static/CMakeLists.txt b/test/unit_test/static/CMakeLists.txt
index a9d0c5ac..9ff4a8ad 100644
--- a/test/unit_test/static/CMakeLists.txt
+++ b/test/unit_test/static/CMakeLists.txt
@@ -31,13 +31,11 @@ if(NOT UNITS_LIBCXX)
         quantity_point_kind_test.cpp
     )
 endif()
-target_link_libraries(unit_tests_static_truncating
-    PRIVATE
-        mp-units::mp-units
+target_link_libraries(unit_tests_static_truncating PRIVATE
+    mp-units::mp-units
 )
-target_compile_options(unit_tests_static_truncating
-    PRIVATE
-        $<IF:$<CXX_COMPILER_ID:MSVC>,/wd4242 /wd4244,-Wno-conversion>
+target_compile_options(unit_tests_static_truncating PRIVATE
+    $<IF:$<CXX_COMPILER_ID:MSVC>,/wd4242 /wd4244,-Wno-conversion>
 )
 
 add_library(unit_tests_static
@@ -71,8 +69,7 @@ if(NOT UNITS_LIBCXX)
     )
 endif()
 
-target_link_libraries(unit_tests_static
-    PRIVATE
-        unit_tests_static_truncating
-        mp-units::mp-units
+target_link_libraries(unit_tests_static PRIVATE
+    unit_tests_static_truncating
+    mp-units::mp-units
 )