const FHSIZE = 32;
typedef opaque fhandle[FHSIZE];

union fhstatus switch (unsigned int status) {
 case 0:
   fhandle directory;
 default:
   void;
};

program MOUNTPROG {
       version MOUNTVERS {
               void MOUNTPROC_NULL(void) = 0;
               fhstatus MOUNTPROC_MNT(dirpath) = 1;
               ...
       } = 1;
} = 100005;