MODULE tsetops;
// SET OF enum + SET OF char-range, INCL/EXCL, SHIFT/ROTATE.
TYPE Colour = (Blue, Red, Green, White);
     CS = SET OF Colour;
     Chars = SET OF ['A'..'z'];
VAR x : CS; c : Chars; r : CS;
VAR ExitCode : INTEGER;
BEGIN
  x := CS {};
  INCL(x, Red); INCL(x, Blue); EXCL(x, Red);
  c := Chars {'A'};
  r := SHIFT(CS {Blue}, 1);          (* {Blue}(bit 0) -> {Red}(bit 1) *)
  IF (Blue IN x) AND NOT (Red IN x) AND ('A' IN c) AND (Red IN r)
  THEN ExitCode := 42 ELSE ExitCode := 1 END
END tsetops.