I'm looking to define local units specific to each instance of a class. In this specific case I need to define a unit called "ticks" that is an angle defined relative to degree_base_unit and radian_base_unit. Local unit definitions are required because I am dealing with varying physical motors that measure their position in "ticks". The number of ticks per radian is arbitrarily defined by the manufacturer, so each class needs an independent "ticks" definition for that specific device loaded by a config file at runtime (so the user is not required to recompile every time they use a new motor). Some of the pieces I need look to be there within a combination of the examples: http://www.boost.org/doc/libs/1_45_0/libs/units/example/runtime_conversion_f... - Defines a runtime conversion for global units defined to exist at compile time <http://www.boost.org/doc/libs/1_45_0/libs/units/example/runtime_conversion_factor.cpp> http://www.boost.org/doc/libs/1_45_0/libs/units/example/radar_beam_height.cp... - Defines a global unit defined at compile time <http://www.boost.org/doc/libs/1_45_0/libs/units/example/radar_beam_height.cpp> http://www.boost.org/doc/libs/1_45_0/libs/units/example/runtime_unit.cpp - Only works for units defined at compile time The key problem here is that I need to define my units locally since they are irrelevant anywhere else while retaining the conversion and type safety of boost.units. It looks like the macros BOOST_UNITS_DEFINE_CONVERSION_FACTOR and BOOST_UNITS_DEFINE_CONVERSION_FACTOR_TEMPLATE both require definition in the global namespace. Any thoughts would be greatly appreciated. Cheers! Andrew Hundt