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

    The clnt_create_vers routine creates an RPC client handle
    for prognum. An RPC client handle is a structure containing
    information about the RPC client. The client can use the UDP
    or TCP transport protocol.

    This routine uses the Portmapper. You cannot control the local
    port.

    The default sizes of the send and receive buffers are 8800 bytes
    for the UDP transport, and 4000 bytes for the TCP transport. The
    retry time for the UDP transport is 5 seconds.

    The clnt_create_vers routine differs from the standard clnt_
    create routine in that it seeks out the highest version number
    supported by the server. If the server does not support any
    version numbers within the requested range, the routine returns
    NULL and the versnum variable is undefined.

    The clnt_create_vers routine uses the global variable rpc_
    createerr. rpc_createerr is a structure that contains the most
    recent service creation error. Use rpc_createerr if you want the
    client program to handle the error. The value of rpc_createerr is
    set by any RPC client creation routine that does not succeed.