20 Library introduction [library]

20.5 Library-wide requirements [requirements]

20.5.5 Conforming implementations [conforming] Moved-from state of library types [lib.types.movedfrom]

Objects of types defined in the C++ standard library may be moved from ([class.copy]).
Move operations may be explicitly specified or implicitly generated.
Unless otherwise specified, such moved-from objects shall be placed in a valid but unspecified state.