ost_regex.syntax.basic_extended.collating_elements">Collating
        Elements:</a>
      </h6>
<p>
        An expression of the form <code class="computeroutput"><span class="special">[[.</span><span class="identifier">col</span><span class="special">.]</span></code> matches
        the collating element <span class="emphasis"><em>col</em></span>. A collating element is any
        single character, or any sequence of characters that collates as a single
        unit. Collating elements may also be used as