VMS Help TCPIP Services, Programming Interfaces, RPC Client Routines, clnt_create_#, 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.
 protocol
    A pointer to a string containing the name of the protocol for
    transmitting and receiving RPC messages. Specify either tcp or
    udp.