       <th scope="row"><code>tree</code></th>
              <td></td>
              <td><code>ul</code></td>
              <td>
                <ul>
                  <li>Identifies the <code>ul</code> element as a <code>tree</code> widget.</li>
                  <li>
                    The tree element is not focusable because it implements the practice described in
                    <a href="../../../practices/keyboard-interface/keyboard-interface-practice.html#kbd_roving_tabindex">Managing Focus Withi