*** The functions read-buffer, read-variable, read-command, read-string<BR>
read-file-name, read-from-minibuffer and completing-read now take an
additional argument which specifies the default value.  If this
argument is non-nil, it should be a string; that string is used in two
ways:
<P>
  It is returned if the user enters empty input.
  It is available through the history command M-n.
<P>