This book could be much worse (all the way down to the point of nonexistence) without the help of the following people to whom I am deeply indebted:
Charles F. Goldfarb, for inventing SGML before I was born, for persuading me that the book project is realistic, and for a detailed review of the manuscript.
Mark Taub, for managing the project and tirelessly pushing me ahead despite my tendency to procrastinate.
G. Ken Holman, for pointing out some finer points of XSLT and catching many ambiguities and outright errors.
Daniel Smith, for useful comments on writing style and presentation of the material.
Vadim Penzin, for useful discussions of database terminology.
Ilya Oussov, for help with Java extension functions.
Alina, for everything.