<!DOCTYPE html>
<html>
<head>
  <meta charset=utf-8>
  <title>&lt;h1&gt;</title>
</head>
<body>
  <!-- is not strictly inline -->
  <p><dfn>text 
    <h1>more text</h1>
  </dfn></p>

  <!-- is not structured inline -->
  <p>text
    <h1>more text</h1>
  </p>

  <!-- cannot contain blocks -->
  <h1>
    <p>p1</p>
    <p>p2</p>
  </h1>

  <!-- cannot contain structured inline -->
  <h1>text
    <ul><li>text</li></ul>
  </h1>
</body>
</html>