cobol DISPLAY statement DISPLAY UPON


Example

DISPLAY "An error occurred with " tracked-resource UPON SYSERR

DISPLAY A, B, C UPON CONSOLE

DISPLAY group-data UPON user-device
    ON EXCEPTION
        WRITE device-exception-notice
    NOT ON EXCEPTION
        WRITE device-usage-log
END-DISPLAY

UPON CONSOLE is a default, rarely written. Messages with DISPLAY are one way of debugging COBOL code, but many COBOL programs are transactional in nature, and might not ever interact with a human operator once a job is submitted.