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

 handle
    A pointer to a client handle created by any of the client handle
    creation routines.
 errp
    A pointer to an rpc_err structure containing information that
    indicates why an RPC call failed. This information is the same
    information as clnt_stat contains, plus one of the following:
    the C error number, the range of server versions supported, or
    authentication errors.