MODULE TNestRec;
// Nested recursion + up-level accumulator. Exit 15.
VAR ExitCode : INTEGER;
PROCEDURE Walk(n : INTEGER);
VAR acc : INTEGER;
  PROCEDURE Down(k : INTEGER);
  BEGIN
    IF k <= 0 THEN RETURN END;
    acc := acc + k;
    Down(k - 1)
  END Down;
BEGIN
  acc := 0;
  Down(n);
  ExitCode := acc
END Walk;
BEGIN
  Walk(5)
END TNestRec.