truct backref"><tt>\</tt><i>n</i></td>
     <td valign="bottom" headers="matches">Whatever the <i>n</i><sup>th</sup>
     <a href="#cg">capturing group</a> matched</td></tr>

 <tr><th>&nbsp;</th></tr>
 <tr align="left"><th colspan="2" id="quot">Quotation</th></tr>

 <tr><td valign="top" headers="construct quot"><tt>\</tt></td>
     <td headers="matches">Nothing, but quotes the following character</tt></td></tr>
 <tr><td valign="top" headers="construct quot"><tt>\Q</tt></td>
     <td headers="matches">Nothin