Extension functions in Xalan Java 2 are bound using two Xalan extensions, xalan:component and xalan:script, where the relevant Xalan namespace URI is http://xml.apache.org/xslt.

The xalan:component element associates the extension namespace prefix with the names of extension functions or elements that will be defined by the enclosing xalan:script element. The xalan:script element defines the language used to implement the extension and its associated implementation. The choices here vary. Casual users of Java-based extensions should note that Xalan supports an abbreviated syntax that does not require the use of the xalan:component or xalan:script elements. Simply declare the namespace in one of the forms shown here, and invoke the Java function using the appropriate syntax. For scripting languages, this shortcut does not apply.