in the tab sequence.</li>
                  <li>Only one <code>treeitem</code> in the <code>tree</code> has <code>tabindex="0"</code>.</li>
                  <li>In this implementation, the first <code>treeitem</code> in the <code>tree</code> is included in the tab sequence when the page loads.</li>
                  <li>
                    When the user moves focus in the <code>tree</code>, the element included in the tab sequence changes to the element with focus as described in
                    <a hr