serif::dimensions::Opacity serif::dimensions::PhysicalQuantity dimensions.hpp std::string_view std::string_view serif::dimensions::Opacity::identifier identifier serif::dimensions::Opacity::identifier = "opacity" Dimension of Opacity. we are not currently using this in the code since we are still using a polytropic eos. However, when we actually get to using this we will likely want to break this out into more specific and meaningful opacity dimensions (RMO, per unit wavelength, etc...) serif::dimensions::Opacity serif::dimensions::PhysicalQuantity serif::dimensions::Opacity identifier serif::dimensions::PhysicalQuantity std::basic_string_view< Char > std::string_view serif::dimensions::Opacityidentifier