It's a given: to effectively share XML documents you need have a point of reference such as a standard DTD, shared by both parties. The obvious step is to create a repository for the DTDs, organised into categories, perhaps each with it's own working group and mailing list. This is what people need, we are told. If you need a DTD for calendar events, don't write one, visit the repository and use one that someone else has invested the time and effort in creating. If this is what we need then why do so many repositories fail. Look at XML Exchange - page upon page of cobwebbed forums, or Schema.net - last updated May 1999. There has been so little activity in the latter that there the 'What's New' link isn't even connected.What about XML.ORG's XML Registry and Repository? Never implemented. In fact the only one to claim any sort of success is BizTalk. Why is that? What makes BizTalk different? Will DTD.COM fare any better? Perhaps only time will tell.