/td>
      <td>::=</td>
      <td>&apos;&quot;&quot;&quot;&apos; <code>(</code> <code>(</code> '<code class="grammar-literal">&quot;</code>' <code>|</code> &apos;&quot;&quot;&apos;<code>)</code> <code>?</code>  <code>(</code> <code>[</code> <code class="grammar-literal">^&quot;\</code><code>]</code>  <code>|</code> <a href="#tg-grammar-production-ECHAR">ECHAR</a> <code>|</code> <a href="#tg-grammar-production-UCHAR">UCHAR</a><code>)</code> <code>)</code> <code>*</code>  &apos;&quot;&quot;&quot;&apos;</td>
 