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

    Serializes and deserializes discriminant unions.
    Format
      #include  <tcpip$rpcxdr.h>
      bool_t  xdr_union(XDR *xdrs, enum *dscmp, char *unp, struct
              xdr_discrim *choices, xdrproc_t default);

  Additional Information (explode) :

• Arguments
• Description
• Return Values