ABC: procedure options (main);   /* 12 January 2014 */

   declare word character (20) varying, blocks character (200) varying initial
      ('((B O) (X K) (D Q) (C P) (N A) (G T) (R E) (T G) (Q D) (F S)
        (J W) (H U) (V I) (A N) (O B) (E R) (F S) (L Y) (P C) (Z M))');
   declare tblocks character (200) varying;
   declare (true value ('1'b), false value ('0'b), flag) bit (1);
   declare ch character (1);
   declare (i, k) fixed binary;

   do word = 'A', 'BARK', 'BOOK', 'TREAT', 'COMMON', 'SQuAd', 'CONFUSE';
      flag = true;
      tblocks = blocks;
      do i = 1 to length(word)
      while(flag = true);
         ch = substr(word, i, 1);
         k = index(tblocks, uppercase(ch));
         if k = 0 then
            flag = false;
         else /* Found a block with the letter on it. */
            substr(tblocks, k-1, 4) = '   '; /* Delete the block. */
      end;
      if flag then put skip list (word, 'true'); else put skip list (word, 'false');
   end;

end ABC;