anism for extending XHTML.</p>
</li>

<li>
<p>It simplifies the transformation between document types.</p>
</li>

<li>
<p>It promotes the reuse of modules in new document types.</p>
</li>
</ul>

<h2><a name="profiles" id="profiles">6.3 Document
Profiles</a></h2>

<p>A document profile specifies the syntax and semantics of a set
of documents. Conformance to a document profile provides a basis
for interoperability guarantees. The document profile specifies
the facilities required to process documents of that 