This section describes the constraints upon, and latitude of, implementations of the C++ standard library.
An implementation's use of headers is discussed in [res.on.headers], its use of macros in [res.on.macro.definitions], non-member functions in [global.functions], member functions in [member.functions], data race avoidance in [res.on.data.races], access specifiers in [protection.within.classes], class derivation in [derivation], and exceptions in [res.on.exception.handling].