    <a href="terminology.html#must-requirement" id="must-requirement_xref13">must</a>
      be the name of
      the character encoding used to serialize the file.</li>
      <li>The value
      <a href="terminology.html#must-requirement" id="must-requirement_xref14">must</a>
      be a valid character encoding name, and
      <a href="terminology.html#must-requirement" id="must-requirement_xref15">must</a>
      be the preferred name for that encoding,
      as specified in
      the IANA
      <a href="re