Each name declared as an object with external linkage
in a header is reserved to the implementation to designate that library
object with external linkage,179
both in namespace std and in the global namespace.
Each function signature from the C standard library declared with
is reserved to the implementation for use as
a function signature with both
or as a name of namespace scope in the global namespace.
The function signatures declared in
are always reserved, notwithstanding the restrictions imposed in subclause
4.5.1 of Amendment 1 to the C Standard for these headers.