This version of DFU optionally uses Screen Management (SMG) routines
 to perform output. DFU will automatically select line mode unless
 the logical DFUSMG is defined and the terminal does not have SMG
 capabilities, if DFU is executed in a batch job or if the logical
 DFU$NOSMG is defined. In any of these 3 cases DFU will switch to
 normal line oriented output. The default is line mode.
    DFU can be forced to SMG (full display) mode by defining the
    logical DFU$SMG to any value. DFU can be forced to line mode
    output by defining the logical DFU$NOSMG to any value.

    In SMG mode the /PAGE qualifier will present output page by page.
    This may be handy for some commands which produce a large amount
    of output (SEARCH, REPORT).

    In SMG mode the following keys perform special functions (Keys
    between () are keys on a PC keyboard) :

    o  CTRL/W : Redraws the screen

    o  HELP or PF2 (/) : Invokes the help facility

    o  PF4 (-) : Dumps the screen contents to file DFU_SCREEN.TXT

    o  PREV_SCREEN (PageUp) : Scrolls the output window back (one
       screen)

    o  NEXT_SCREEN (PageDown): Scrolls the output window forward (one
       screen)

    o  INSERTHERE (Insert) : Scrolls the output window back (one
       line)

    o  REMOVE (Delete) : Scrolls the output window forward (one line)

    o  SELECT (End) : Toggle between 80/132 columns

    o  UP/DOWN : Recall command buffer