VMS Help TCPIP Services, Programming Interfaces, RPC Client Routines, clnttcp_create, Arguments  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 addr
    A pointer to a buffer containing the internet address where the
    remote program is located.
 prognum
    The program number associated with the remote procedure.
 versnum
    The version number associated with the remote procedure.
 sockp
    A pointer to the socket number to be used for the remote
    procedure call. If sockp is RPC_ANYSOCK, then this routine opens
    a new socket and sets sockp.
 sendsize
    The size of the send buffer. If you specify 0 the routine chooses
    a suitable default.
 recvsize
    The size of the receive buffer. If you specify 0 the routine
    chooses a suitable default.