Your terminal has special keys that allow you to recall and edit
  previous commands.  Note that some of these keys might not be
  available on your keyboard.

  Recalling Commands
  ------------------
  The system saves and allows you to access up to 254 of your most
  recently  entered commands.   The size of the recall buffer is 4Kb,
  which will store approximately 80 commands at 48 characters each. If
  the length of stored commands makes it necessary, one or more of the
  oldest commands will be removed from the recall buffer to make room for
  the most recent command.

  Use the up arrow or Ctrl/B keys to recall previously entered commands.
  Use the down arrow key to reexamine a command that you previously
  viewed using the up arrow.

  If you are supplying commands or data to a program or utility, the
  system saves and allows you to access only your single most recently
  entered command.

  Editing Commands
  ----------------
  To enable the editing keys, enter the following command:

         SET TERMINAL/LINE_EDITING

  You can add the /OVERSTRIKE or /INSERT qualifiers to the command to
  specify the default editing mode that you prefer.  The /OVERSTRIKE
  qualifier causes a character that you type to be written over the
  character that the cursor is currently pointing at.  The /INSERT
  qualifier causes the character to be inserted before the cursor.

  Restrictions on using these commands are outlined after the
  command descriptions.

  Edit Key        Function
  --------        --------
  Ctrl/A or       Switches between overstrike mode and insert mode. The
  F14             default mode is reset at the beginning of each line.

  Ctrl/D or       Moves the cursor one character to the left.
  Left Arrow

  Ctrl/E          Moves the cursor to the end of the line.

  Ctrl/F or       Moves the cursor one character to the right.
  Right Arrow

  Ctrl/H or       Moves the cursor to the beginning of the line.
  Backspace or
  F12

  Ctrl/J or       Deletes the word to the left of the cursor.
  Linefeed or
  F13

  Ctrl/U          Deletes characters from the beginning of the line to
                  the cursor.

  Restrictions
  ------------
  When you use the terminal driver's editing functions, the following
  restrictions apply:

  - You cannot move the cursor to a previous line after a line wrap.

  - You cannot insert a character if the insertion would force a line
    wrap or if a tab follows the current cursor position.

  - You cannot delete a word at the beginning of a line after a line wrap.

  - You cannot assign the line editing function to other keys.