Henry S. Thompson is Managing Director of Markup Technology Ltd. He is also Reader in Artificial Intelligence and Cognitive Science in the Division of Informatics at the University of Edinburgh, based in the Language Technology Group of the Human Communication Research Centre. He received his Ph.D. in Linguistics from the University of California at Berkeley in 1980. His university education was divided between Linguistics and Computer Science, in which he holds an M.Sc. His research interests have ranged widely, including natural language parsing, speech recognition, machine translation evaluation, modelling human lexical access mechanisms, the fine structure of human-human dialogue, language resource creation and architectures for linguistic annotation. His current research is focussed on articulating and extending the architectures of XML. Markup Technology is focussed on delivering the power of XML pipelines for application development. Henry was a member of the SGML Working Group of the World Wide Web Consortium which designed XML, is the author of the XED, the first free XML instance editor and co-author of the LT XML toolkit and is currently a member of the XSL and XML Schema Working Groups of the W3C. He currently is a member of the W3C Team, and is lead editor of the Structures part of the XML Schema W3C Recommendation, for which he co-wrote the first publicly available implementation, XSV. He has presented many papers and tutorials on SGML, DSSSL, XML, XSL and XML Schemas in both industrial and public settings over the last five years.