Mr. Bourret is the clever guy who wrote the XML-DBMS package. This article, however, appears to be part of a growing trend at the Oreilynet collective to simply repackage existing documentation or presentations and sell them as capital-A articles. Maybe it's always been this way and I've only just caught up with the practice. I'm not even sure I think it's a bad thing since you could make a reasonable argument that it provides and effective vehicle for people to learn about cool stuff. Still, it just seems a bit cheap. Anyway, I love DTDs...