You mean, why does the output include the xdt and fn namespaces?
It's part of the specification of literal result elements that all the in-scope namespaces from the stylesheet are copied to the result document unless you request otherwise. You can request otherwise using exclude-result-prefixes="xdt fn" on the xsl:stylesheet element.
Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference