Additional Resources
There are a number of places on the Web where you can go to do research on schemas and DTDs. These are sites that might have a DTD that already does what you are looking for, or that may contain links to industry standards. There are also a few software packages that allow you to edit and work with DTDs:
BizTalk (http://www.biztalk.org)— BizTalk is a Microsoft-led initiative to facilitate businesses in utilizing XML and other standards. Although it is a Microsoft-based site, there are still some good resources here, especially those related to business XML formats.
OASIS XML.org (http://www.xml.org)— OASIS is the Organization for the Advancement of Structured Information Standards, and it is an industry group composed of more ...