31 Thread support library [thread]

31.2 Requirements [thread.req]

31.2.3 Native handles [thread.req.native]

Several classes described in this Clause have members native_­handle_­type and native_­handle.
The presence of these members and their semantics is implementation-defined.
These members allow implementations to provide access to implementation details.
Their names are specified to facilitate portable compile-time detection.
Actual use of these members is inherently non-portable.
end note