<html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <title>&lt;em&gt;</title>
</head>
<body>
  <!-- is structured inline -->
  <p><em class="class" xml:lang="en">text</em></p>

  <!-- is strictly inline -->
  <p><dfn><em class="class" xml:lang="en">text</em></dfn></p>

  <!-- can be empty -->
  <p>text <em></em></p>
  <p>text <dfn><em></em></dfn></p>

  <!-- can contain interactive -->
  <p><em><a>text</a></em></p>
  <p><dfn><em><a>text</a></em></dfn></p>

</body>
</html>