p</b> from the menu.</p></li>
<li><p>On the MacOS system, for a X11 device the identification process is 
  terminated by pressing any mouse button other than the first, and for a 
  quartz device this process is terminated by pressing the <b>ESC</b> key.</p></li>
</ul>
    <p>Once the user terminates the identification process, the current 
graphics window will be closed automatically, and the graphics window of
the following segment is activated. When all graphics windows are closed,
<code>ring_modify</co