</i></a>
                |   <i>extended-regexp</i> <b>"|"</b> <a href="#branch"><i>branch</i></a>
</pre>
</td></tr>
</table>
<p>
An extended regexp (ERE) is one or more <i>branches</i>, separated by
<tt>|</tt>.  An ERE matches anything that matches one or more of the
branches.
</p>

<h3>Catenation of REs</h3>
<a name="catenation"></a>
<a name="branch"></a>

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<tr><td>
<pre>
<i>branch</i> ::= <i>piece</i>
       |   <i>branch</i> <i>piece</i>
</pre>
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</tabl