You enter the keypad mode of change mode when your terminal is a
 VT100-type or VT52 and the keypad option is set.  (This option is set by
 default for these terminals.)  In this mode the terminal screen is used
 to view the text buffer.  Characters typed using the main keyboard are
 inserted into the buffer at the cursor position.  You enter editing
 commands by using keys on the auxiliary keypad, function keys, or
 control keys on the main keyboard.

 For more help on keypad mode, type CHANGE to enter that mode.  Use the
 keypad HELP facility as follows:

     1.  If your terminal is a VT100-type, press the keypad key marked PF2.
     2.  If your terminal is a VT52, press the red keypad key.
     3.  If your terminal has function keys, press the function key marked
         HELP.