THIS BOOK HAS BEEN UPDATED. XSLT PROGRAMMER'S REFERENCE, 2ND EDITION (ISBN 1861005067), IS AVAILABLE TO ORDER NOW XSL (eXtensible Stylesheet Language) is the styling language to match XML. At the most basic level it allows the programmer to manipulate XML on a template model - XSL provides the template to fit XML data into for displaying on a web page. However, it is capable of much more than that, and allows programmers to selectively query, display and manipulate data, perform scripting-like operations on the XML document and transform it into pure HTML for use on browsers which don't support XML.
This book came my way as a gift during a period where I'd fallen into some projects that involved XSLT rather heavily. I was having some trouble "bringing it all together" on my own and this book certainly helped me to pound through those roadblocks. It is about as comprehensive as you can get on the subject without actually merging into an expert's brain. That said, I find it difficult to find specific nuggets of information and the examples and use-cases are not always clear. Also: ease off the Microsoft-centric examples, please.
This book was very useful to me as a reference between 2001-2004. We were using XSLT transformations heavily in the software we were developing at the time.
I do occasionally refer to back to it from time to time when an XSLT problem presents itself at work.