itle="U+0022 QUOTATION MARK">"</code>"
      character or a
      "<code title="U+0027 APOSTROPHE">'</code>"
      character.</li>
      <li>The literal string
      "<code>about:legacy-compat</code>".</li>
      <li>A matching <i>quote mark</i>, identical to the
      <i>quote mark</i> used earlier (either a
      "<code title="U+0022 QUOTATION MARK">"</code>"
      character or a
      "<code title="U+0027 APOSTROPHE">'</code>"
      character).</li>
      <li>Optionally, one or more
      <a href="termin