chromium/content/test/data/accessibility/html/accordion.html

<!--
@ANDROID-ALLOW:expand*
@ANDROID-ALLOW:collapse*
@ANDROID-ALLOW:action_*
@AURALINUX-ALLOW:expanded*
@AURALINUX-ALLOW:collapsed*
@WIN-ALLOW:EXPANDED*
@WIN-ALLOW:COLLAPSED*
@BLINK-ALLOW:collapsed*
@BLINK-ALLOW:expanded*
@MAC-ALLOW:AXExpanded
-->
<html>
<body>
  <!--Section #1-->
  <h3>
    <button id="header1control" aria-controls="section1" aria-expanded="true">
      <p>Accordion Section #1</p>
    </button>
  </h3>
  <div role="region" id="section1" aria-labelledby="header1control">
    <p>Content for first section of accordion element.</p>
  </div>

  <!--Section #2-->
  <h3>
    <button id="header2control" aria-controls="section2" aria-expanded="false">
      <p>Accordion Section #2</p>
    </button>
  </h3>
  <div role="region" id="section2" aria-labelledby="header2control" hidden>
    <p>Content for second section of accordion element.</p>
  </div>

  <!--Section #3-->
  <h3>
    <button id="header3control" aria-controls="section3" aria-expanded="false">
      <p>Accordion Section #3</p>
    </button>
  </h3>
  <div role="region" id="section3" aria-labelledby="header3control" hidden>
    <p>Content for third section of accordion element.</p>
  </div>

  <!--Section #4-->
  <h3>
    <button id="header4control" aria-controls="section4" aria-expanded="true" aria-disabled="true">
      <p>Accordion Section #4</p>
    </button>
  </h3>
  <div role="region" id="section3" aria-labelledby="header4control">
    <p>Content for forth section of accordion element. This section will always be visible but disabled.</p>
  </div>
</body>
</html>