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

 xdrs
    A pointer to an XDR stream handle created by one of the XDR
    stream handle creation routines.
 objpp
    A pointer to a pointer to the data being converted.
 objsize
    The size of the data structure in bytes.
 objproc
    The XDR procedure that filters the structure between its local
    form and its external representation.