Excellent XML reference
A very good book, with superb attention to detail that covers much of the principles and modern applications of the XML language and its related technologies.
Anyone building large XML-based applications will benefit from this book as it is very well researched, and, although a little out of date now, still a good starting point as well as a propelling point for already experienced programmers.
The only sad part of buying this book is that, since it's no longer supported, you cannot find the accompanying video files that came with the book via the website. But that's a small price to pay for a very good XML reference that should be a strong building block for a wide variety of programmers and developers.