The last three versions of Visual Studio (2010, 2008, and 2005) use the XSLT.NET XslCompiledTransform processor . XslCompiledTransform does not implement any EXSLT function except common:node-set() - so here you are out of luck.
I don’t think there is a simple and natural way to use other XSLT processors in Visual Studio, and there might even be some trick to do this, in which case XSLT could not be debugged.
Finally, EXSLT usually provides a limited XSLT implementation of some EXSLT functions. This, of course, is much less powerful and convenient, but you can go along this route.
My personal recommendation is to start using XSLT 2.0 , which is much more powerful than XSLT 1.0, and very little is needed to use EXSLT in an XSLT 2.0 application.
Of course, VS does not support XSLT 2.0, but there are other great IDEs like oXygen, which, among other things, provide good XSLT 2.0 and XQuery debuggers.
Update . You can use a third-party implementation of EXSLT for XslCompiledTransform: MVP - XML project EXSLT.NET module .
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