<article>
  <front>
    <article-meta>
      <title-group>
        <article-title>So many format issues</article-title>
      </title-group>
    </article-meta>
  </front>
  <article-body>
    <p>Unknown markup tag.</p>
    <section>
      <h2>In sections too</h2>
      <p>Again unknown tag.</p>
    </section>
  </article-body>
</article>
