>>I have not see any developer using DTD to handle dynamically different document formats.

Just beause you haven't seen it doesn't mean it's not good or it's not being used by others. In fact I have used it in a way that makes maintenance of my applications a lot easier than before. I process data from multiple vendors and they of course change their formats frequently. Having code that will dynamically adjust to a change in the XML schema has been great for me. But of course, beauty is in the eye of the beholder, so I'm not claiming everyone should be doing that. In the end XML is one more tool that happens to work for many of us.