serif::dimensions::Mass serif::dimensions::PhysicalQuantity dimensions.hpp std::string_view std::string_view serif::dimensions::Mass::identifier identifier serif::dimensions::Mass::identifier = "mass" Dimension of mass. serif::dimensions::Mass serif::dimensions::PhysicalQuantity serif::dimensions::Mass identifier serif::dimensions::PhysicalQuantity std::basic_string_view< Char > std::string_view serif::dimensions::Massidentifier