VMS Help TCPIP Services, Programming Interfaces, Sockets API, shutdown(), Errors  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    EBADF              The socket descriptor is invalid.
    EINVAL             The how argument is invalid.
    ENOBUFS            The system has insufficient resources to
                       complete the call.
    ENOTCONN           The specified socket is not connected.
    ENOTSOCK           The socket descriptor is invalid.