F3:  This key copies all remaining characters from the retained line to the
current line.  For example, suppose  DIR B:  is the retained line.  If you press
F3  (without having typed any characters on the current line), then the entire
retained line will be copied to the current line.  The current line would be
DIR B:

If the retained line is XIR B: you could easily execute the command DIR B: by
doing the following:

   Enter D as the first character of the current line, and then press F3 to copy
   all remaining characters (IR B:) from the retained line to the current line.
   The current line now reads DIR B:


On the PCjr:  Hold down FN and press 3.
