16 Library introduction [library]

16.4 Library-wide requirements [requirements]

16.4.2 Library contents and organization [organization]

16.4.2.2 Library contents [contents]

The C++ standard library provides definitions for the entities and macros described in the synopses of the C++ standard library headers ([headers]), unless otherwise specified.
All library entities except operator new and operator delete are defined within the namespace std or namespaces nested within namespace std.165
It is unspecified whether names declared in a specific namespace are declared directly in that namespace or in an inline namespace inside that namespace.166
Whenever a name x defined in the standard library is mentioned, the name x is assumed to be fully qualified as ​::​std​::​x, unless explicitly described otherwise.
For example, if the Effects: element for library function F is described as calling library function G, the function ​::​std​::​G is meant.
The C standard library headers ([depr.c.headers]) also define names within the global namespace, while the C++ headers for C library facilities ([headers]) may also define names within the global namespace.
 
This gives implementers freedom to use inline namespaces to support multiple configurations of the library.