A type X meets the AcceptableProtocol requirements if it satisfies the requirements of Protocol ([socket.reqmts.protocol]) as well as the additional requirements listed below.
| expression | return type | assertion/note pre/post-conditions |
| X::socket | A type that satisfies the requirements of Destructible (C++ 2014 [destructible]) and MoveConstructible (C++ 2014 [moveconstructible]), and that is publicly and unambiguously derived from basic_socket<X>. |