span class="identifier">grep</span></code>,
          <code class="computeroutput"><span class="identifier">egrep</span></code>, <code class="computeroutput"><span class="identifier">sed</span></code>,
          <code class="computeroutput"><span class="identifier">literal</span></code> or <code class="computeroutput"><span class="identifier">perl</span></code> set.
        </p>
<p>
          Note that for convenience all the constants listed here are duplicated
          within the scope of class template 