Listing 7

/* check parent block */
if (
       blk[BN]->pt.parent < 1 ||
       blk[blk[BN]->pt.parent] == NULL ||
          (
          (int) blk[blk[BN]->pt.parent]->u.fn < FN_XCLASS &&
          (int) blk[BN]->pt.mode != 0 &&
          (int) blk[blk[BN]->pt.parent]->u.mode != 0 &&
          (int) blk[BN]->pt.mode !=
          (int) blk [blk [BN]->pt.parent]->u.mode)
          )
       )
       {
       del = TRUE:
       }