.html#must-requirement" id="must-requirement_xref28">must</a>
      never be two or more attributes on the same
      start tag whose names are a
      <a href="terminology.html#case-insensitive" id="case-insensitive_xref11">case-insensitive match</a>
      for each other.</p>
      <p id="attributes-basic-syntax">The following list describes syntax
        rules for attributes in 
        <a href="documents.html#syntax-document-html" id="syntax-document-html_xref8">documents in the HTML syntax</a>.
       