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

 xprt
    A pointer to an RPC server handle created by any of the server
    handle creation routines.
 low_vers
    The lowest version of the requested program that the server
    supports.
 high_vers
    The highest version of the requested program that the server
    supports.