MODULE Extern;

PROCEDURE Inside (x: INTEGER): BOOLEAN =
  BEGIN
    RETURN (x = 17);
  END Inside;

<*EXTERNAL*> PROCEDURE AnotherExtern (x: INTEGER): BOOLEAN;

<*EXTERNAL*> VAR anotherExtern: INTEGER;

BEGIN
EVAL AnotherExtern (anotherExtern);
EVAL Outside (inside);
EVAL Outside (outside);
END Extern.