text/html
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<ul>
  <li>
    <ol>
      <li>One</li>
      <li>Two</li>
      <li>Three</li>
    </ol>
    <ol>
      <li>Four</li>
      <li>Five</li>
      <li>Six</li>
    </ol>
  </li>
  <li>
    <ol>
      <li>Seven</li>
      <li>Eight</li>
      <li>Nine</li>
    </ol>
    <ol>
      <li>Ten</li>
      <li>Eleven</li>
      <li>Twelve</li>
    </ol>
  </li>
</ul>

text/plain
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  - 1.  One
    2.  Two
    3.  Three

    1.  Four
    2.  Five
    3.  Six

  - 1.  Seven
    2.  Eight
    3.  Nine

    1.  Ten
    2.  Eleven
    3.  Twelve