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

    This function allows communications on a socket to be shut down
    one piece at a time rather than all at once. Use the shutdown()
    function to create unidirectional connections rather than the
    normal bidirectional (full-duplex) connections.
    Related Functions
    See also connect() and socket().