     for the string "<code>xml</code>".</li>
      <li>
      <dfn id="syntax-attribute-value">attribute values</dfn>, in
      general, are
      <a href="syntax.html#normal-character-data" id="normal-character-data_xref3">normal character data</a>;
      however, the <a href="elements.html">HTML elements</a> section
      of this reference describes further restrictions on the
      allowed values of particular attributes, and attributes
      <a href="terminology.html#must-requirement" id="must-requireme