Michael Mahan. <a href="http://www.w3.org/TR/2004/NOTE-xopinc-FAQ-20040608"><cite>XOP Inclusion Mechanism - Frequently Asked Questions.</cite></a> 8 June 2004. W3C Note. URL: <a href="http://www.w3.org/TR/2004/NOTE-xopinc-FAQ-20040608">http://www.w3.org/TR/2004/NOTE-xopinc-FAQ-20040608</a>