Thanks for all your kind words. A few thoughts.

As it says in the heading in italics, I originally wrote this 7 years ago. I couldn't get it published then, because it was (and still is, really) counter to the current orthodoxy. I really don't understand the allure of what is essentially a failed idea.

What are XML languages good for? A major clue is in their name: markup languages. Markup languages are created for marking up text. They're not created for, nor are they good at, data transfer or data storage.

Finally, if you do use XML for whatever reason, I strongly recommend sticking with DTD's, as opposed to the far cooler XML Schemas. In my opinion, the extra you get from schemas is not worth the extra obfuscation; in addition, schema processing is still pretty immature. During my time trying to implement the SPL project for the FDA, the official schema compiled in XMLSpy (as an XML file) but didn't compile in another tool (as a schema). What do you do in that case?