[contents] describes the entities and macros defined in the Ranges library.
The Ranges library provides definitions for the entities and macros specified in the Ranges library headers ([headers]).
All library entities are defined within an inline namespace v1 within the namespace std::experimental::ranges or namespaces nested within namespace std::experimental::ranges::v1. It is unspecified whether names declared in a specific namespace are declared directly in that namespace or in an inline namespace inside that namespace.