VT100: EXT + G              VT200: EXT + F14
    DEFINE_KEY Function: SHOW_MESSAGE

    Displays the broadcast messages that have been posted on a
    separate screen. If the status line is enabled, the indicator
    Msg appears on the status line. If you do not read the messages
    before they fill up the screen, the messages begin to scroll up
    out of view and you can no longer read them. These broadcast
    messages are not saved after you either read them or exit
    TN3270.