PCA provides a set of screen features designed to be used on
    VT100 or VT200 class terminals. The command SET MODE SCREEN
    activates screen mode and SET MODE NOSCREEN deactivates it. In
    screen mode, output is stored in "screen displays" which are
    viewed through scrollable windows on the screen.

    The following commands control PCA's screen features:

    SET MODE SCREEN    MOVE               SET WINDOW
    SET MODE NOSCREEN  SCROLL             SHOW WINDOW
    SET DISPLAY        SELECT             CANCEL WINDOW
    SHOW DISPLAY       SHOW SELECT        SET TERMINAL
    CANCEL DISPLAY     SAVE               EXPAND
    DISPLAY

    You can get further information on each of these commands through
    HELP.