   </ol>
    <p>
      Feature status is in practice indicated by
      <a href="https://datatracker.ietf.org/doc/html/rfc2119">RFC&nbsp;2119</a> assertions associated with the feature.
      Features defined using any assertions containing the words MUST are considered required. Features defined using
      MAY and SHOULD assertions are considered optional.
    </p>
    <p>
      Feature utility is indicated indirectly by the number of implementations supporting each feature. In general,
      features wit