The Xalan and Saxon processors support the use of extension elements and extension functions. Unlike a literal result element, which the stylesheet simply transfers to the result tree, an extension element performs an action. The extension is usually used because the XSLT stylesheet fails in providing adequate functions to the user for accomplishing a more complex task.
Samples on how to use extensions can be found at:
In order to set an XSLT processor extension (a directory or a jar file), you have to use the Extensions button of the scenario edit dialog. The old way of setting an extension (using the parameter -Dcom.oxygenxml.additional.classpath) was deprecated and you should use the extension mechanism of the XSLT transformation scenario.