I would like to thank the RELAX NG OASIS Technical Committee for having created the subject of this book, and especially Murata Makoto, James Clark, and John Cowan for the timely and highly accurate answers they have provided to my many questions.

My own implementation of RELAX NG has proven to be most useful in gaining a deep understanding of the language. I would also like to thank Uche Ogbuji, who has been my Python mentor during this project and again James Clark for his detailed instructions of how RELAX NG can be implemented using the derivative algorithm.

This book is the result of a collaborative work, and I thank all the people who contributed comments and annotations, including J. David Eisenberg, John Cowan, and Dave Pawson, who have extended their comments well beyond the scope of simple tech review and have significantly improved its level of quality, as well as Tracey Cranston, who reviewed and edited the prose. This collaborative work would never have started without my editor, Simon St.Laurent, who has believed in this book since before its beginning and made it happen.

Finally, I need to thank my wife and children for their patience and moral support while I was busy writing this book. Unlike in the preface of my previous book, I won't dare to promise that they will recover their husband and father now that this book is over, as I fear that a new challenging project might swallow me in the near future!