XSLT, 2nd Edition

Namespaces for Extensions

XSLT extension elements and extension functions must have a namespace prefix different from the XSLT namespace prefix. For example, here’s the start of a stylesheet that declares several namespace prefixes:

<?xml version="1.0"?>
<xsl:stylesheet version="1.0" 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:svg="http://www.w3.org/2000/svg"
  xmlns:xalan-java="http://xml.apache.org/xslt/java"
  xmlns:saxon-java="java:java.lang.Math"
  extension-element-prefixes="xalan-java saxon-java">

By default, the XSLT processor copies all of the non-XSLT namespaces to the output document. That means the svg, xalan-java, and saxon-java namespaces will be defined in the output. In this example, we’re generating an SVG document using extensions associated with the xalan-java and saxon-java namespaces. We don’t need our extension namespaces defined in the output document, so we use the extension-element-prefixes attribute to make sure they aren’t in the generated document. The svg namespace, on the other hand, will appear in the output document, which is exactly what we want.