tis(ing|ements?))"</span> is optional, as are the
      individual sub-expressions: <span class="QUOTE">"(er)"</span>, <span class="QUOTE">"(ing|ements?)"</span>, and
      the <span class="QUOTE">"s"</span>. The <span class="QUOTE">"|"</span> means <span class="QUOTE">"or"</span>. We
      have two of those. For instance, <span class="QUOTE">"(ing|ements?)"</span>, can expand to match either
      <span class="QUOTE">"ing"</span> <span class="emphasis"><i class="EMPHASIS">OR</i></span> <span class=
      "