I put together a small demonstration of how knowing programming language concepts and Scheme can help you understand XML. My point isn't to show how to do XML inside Scheme or to say Scheme is better than XML. My point is simply to demonstrate that the things my students have been learning in class, which can seem pretty disconnected from things they read about in the trade press, are actually on point. In this case, they see that what they've been doing with BNF, s-expressions, and data-driven programming can help them understand XML and how it is processed.