MODULE TMutual;
// Mutual recursion through FORWARD. Exit 11.
VAR ExitCode : INTEGER;
PROCEDURE Even(n : INTEGER) : BOOLEAN; FORWARD;
PROCEDURE Odd(n : INTEGER) : BOOLEAN;
BEGIN
  IF n = 0 THEN RETURN FALSE END;
  RETURN Even(n - 1)
END Odd;
PROCEDURE Even(n : INTEGER) : BOOLEAN;
BEGIN
  IF n = 0 THEN RETURN TRUE END;
  RETURN Odd(n - 1)
END Even;
BEGIN
  IF Even(10) AND Odd(11) THEN ExitCode := 11 ELSE ExitCode := 0 END
END TMutual.