#include <rms>
  #include <stdio>
  #define MAXKEY 10
  main (int argc, char *argv[])
  {
  struct FAB fab;
  struct XABSUM sum;
  struct XABKEY xab[MAXKEY];
  int  i, stat, lvl, keys;

  fab = cc$rms_fab;
  sum = cc$rms_xabsum;
  fab.fab$b_shr = FAB$M_SHRPUT;
  fab.fab$b_fac = FAB$M_GET;
  fab.fab$l_fna = argv[1];
  fab.fab$b_fns = STRLEN( argv[1] );
  fab.fab$l_xab = &sum;
  stat = SYS$OPEN ( &fab );
  if (!(stat&1)) return stat;
  if (fab.fab$b_org!=FAB$C_IDX) return RMS$_ORG;
  keys = sum.xab$b_nok;
  fab.fab$l_xab = &xab[0];
  for (i=0; i<keys; i++)
       {
       /*
       ** Init Xab Key for each defined key
       ** Point previous to current except first.
       */
       xab[i] = cc$rms_xabkey;
       xab[i].xab$b_ref = i;
       if (i) xab[i-1].xab$l_nxt = &xab[i];
       }
  /*
  ** Ask RMS to fill in the XABs hooked off the FAB.
  */
  stat = SYS$DISPLAY ( &fab );
  if (!(stat&1)) return stat;

  printf ("File %s, Root levels: %d", argv[1], xab[0].xab$b_lvl);
  for (i=1; i<keys; i++) printf (", %d", xab[i].xab$b_lvl);
  printf (".\n");
  return stat;
  }