
Entering printable keys generally inserts new text into the buffer (unless
in overwrite mode, see below).  Other special keys can be used to modify
the text in the buffer.  In the description of the keys below, ^n means
Control-n, or holding the CONTROL key down while pressing "n".  Errors
will ring the terminal bell.

^A/^E   : Move cursor to beginning/end of the line.
^F/^B   : Move cursor forward/backward one character.
^D      : Delete the character under the cursor.
^H, DEL : Delete the character to the left of the cursor.
^K      : Kill from the cursor to the end of line.
^L      : Redraw current line.
^O      : Toggle overwrite/insert mode. Initially in insert mode. Text
          added in overwrite mode (including yanks) overwrite
          existing text, while insert mode does not overwrite.
^P/^N   : Move to previous/next item on history list.
^R/^S   : Perform incremental reverse/forward search for string on
          the history list.  Typing normal characters adds to the current
          search string and searches for a match. Typing ^R/^S marks
          the start of a new search, and moves on to the next match.
          Typing ^H or DEL deletes the last character from the search 
          string, and searches from the starting location of the last search.  
          Therefore, repeated DEL's appear to unwind to the match nearest 
          the point at which the last ^R or ^S was typed.  If DEL is 
          repeated until the search string is empty the search location 
          begins from the start of the history list.  Typing ESC or 
          any other editing character accepts the current match and 
          loads it into the buffer, terminating the search.
^T      : Toggle the characters under and to the left of the cursor.
^Y      : Yank previously killed text back at current location.  Note that
          this will overwrite or insert, depending on the current mode.
^U      : Show help (this text).
TAB     : Perform command completion based on word to the left of the cursor. 
          Words are deemed to contain only the alphanumeric and the % ! ? _  
          characters.
NL, CR  : returns current buffer to the program.

DOS and ANSI terminal arrow key sequences are recognized, and act like:

  up    : same as ^P
  down  : same as ^N
  left  : same as ^B
  right : same as ^F

