ture of
        <a href="documents.html#html-syntax" id="html-syntax_xref9">the HTML syntax</a>
        that is not available in
        <a href="documents.html#xml-syntax" id="xml-syntax_xref6">the XML syntax</a>.
        <a href="documents.html#syntax-document-xml" id="syntax-document-xml_xref9">Documents in the XML
          syntax</a>
        <a href="terminology.html#must-requirement" id="must-requirement_xref48">must</a>
        not contain non-replaceable character
        data as described in this r