This is a simple example of using an extension function in the R XSLT module which is registered in R rather than via the XSL code. This example is intended to be run from within R, in particular using the code in the associated registration.R file. That registers some R functions via the addXSLTFunctions function. These functions are registered with the R extension module in XSLT each time it is initialized and then become available to the XSL rules. The registration.xsl accompanying this file then calls one of those extension functions when transforming the XML. The addXSLTFunctions does not register the functions with the extension module directly. Rather, it maintains them in R and waits for the module to be next initialized. When this occurs, an R function is called which performs the registration. This means