ons on mixed content to enforce the requirement
that <code>param</code>s precede other content.</li>

<li>The forms module takes advantage of RELAX NG's absence of
restrictions on mixed content to enforce the requirement that any
<code>legend</code> precedes other content.</li>

<li>The RELAX NG schema does not enforce exclusions. The HTML 4 DTD
uses exclusions in several places, for example, to disallow an
<code>a</code> element from having an <code>a</code> element as a
descendant. It is not pos