There's a bad habit on this forum of asking questions that relate to one particular XML technology without saying what technology you are talking about. There was an example last week where we had to guess it was Oracle by recognising the version numbers 9i and 10g. On this one, sorry, I don't recognise it. There are any number of XML libraries containing classes with names like XmlNodeReader. I suspect something to do with .NET, but really I've no idea. If you want answers, you need to explain the problem.
Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference