Description: XML namespace. The htc file must be located on the same server as your XSS vector
    http://ha.ckers.org/xss.html#XSS_XML_namespace
Note: I don't completely understand the vector here.  page_structure is what does this.

<HTML xmlns:xss>
  <body>
    <?import namespace="xss" implementation="http://ha.ckers.org/xss.htc">
    <xss:xss>XSS</xss:xss>
  </body>
</HTML>
----------
<HTML>
  <body>
    <div>XSS</div>
  </body>
</HTML>
