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

 host
    A pointer to the name of the remote host.
 prognum
    The program number associated with the remote procedure.
 versnum
    The version number associated with the remote procedure. This
    value is returned by the routine. The value is the highest
    version number supported by the remote server that is in the
    range of version numbers specified by min_vers and max_vers. The
    argument may remain undefined; see additional information in the
    Description section.
 min_vers
    The minimum acceptable version number for the remote procedure.
 max_vers
    The maximum acceptable version number for the remote procedure.
 protocol
    A pointer to a string containing the name of the protocol for
    transmitting and receiving RPC messages. Specify either tcp or
    udp.