What is XML anyway?
The eXtensible Markup Language, or XML, is a simplified version of SGML developed by the World Wide Web Consortium. Unlike the limited tag-set offered by HTML, XML allows authors to define tags based upon the logical structure of their documents. A good introduction to XML is available at http://www.xml.com/xml/pub/98/10/guide0.html. Additional information about XML is available from the World Wide Web Consortium at http://www.w3.org/XML.