HELLO_WORLD: DO;
    /* external I/O routines */
    WRITE$STRING: PROCEDURE( S ) EXTERNAL; DECLARE S POINTER; END WRITE$STRING;
    /* end external routines */
    MAIN: PROCEDURE;
        CALL WRITE$STRING( @( 'Hello world!', 0AH, 0 ) );
    END MAIN;
END HELLO_WORLD;