nd style sheets within comments to make the
documents backward compatible is likely to not work as expected in XML-based
implementations.</p>

<h2>C.5 Line Breaks within Attribute Values</h2>
<p>Avoid line breaks and multiple whitespace characters within
attribute values. These are handled inconsistently by user
agents.</p>

<h2>C.6 Isindex</h2>
<p>Don't include more than one <code>isindex</code> element in
the document <code>head</code>. The <code>isindex</code> element
is deprecated in favor of the <code>