JOHN E. SIMPSON is a Distributed Systems Specialist with the City of Tallahassee, Florida, developing database and Web applications for the Public Works Department. He is the author of Just XML, Second Edition (Prentice Hall PTR) and contributes the monthly "XML Q&A" column to XML.com, the Web's premier XML information site. Simpson has taught the popular "XML from the Ground Up" seminar on Geek Cruises to Alaska and the Caribbean. He recently assisted Microsoft in documenting the features and use of its standards-compliant XML and XSLT processor, MSXML.