gistfile1.txt

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
	xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
	xmlns:my_function="http://example.com">
	<!-- 
		Note the function declaration above.
		While the namespace URI is from the function's extension, I've made up the prefix 'my_function' just for use in this doc.
	-->

<xsl:output method="xml"
	doctype-public="-//W3C//DTD XHTML 1.0 Strict//EN"
	doctype-system="http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"
	omit-xml-declaration="yes"
	encoding="UTF-8"
	indent="yes" />

<!-- include the stream, this does all sorts of awesome  -->	
<xsl:include href='efm://functions' /> 

<xsl:template match="/">
	
	<xsl:variable name='name' select="'I am a boring string.'" />
	<p><xsl:value-of select='my_function:hello($name)' /></p>

</xsl:template>
</xsl:stylesheet>

Manage to get thru the error and how does it locate the 'hello' function in the examples folder?

XSLTProcessor::transformToXml():
xmlXPathCompOpEval: function hello not found
Unregistered function
XPath evaluation returned no result.

We have defined a namespace prefix my_function with a URI http://example.com. This URI maps on to the functions defined in the Hello World example, named hello and hellonode. Make sure you have enabled the Hello World extension.

Brilliant! Appreciate for getting this working.