Michael M. David is founder of Advanced Data Access Technologies, Inc. Previously a staff scientist and the lead XML architect for NCR/Teradata and their representative to the ANSI SQLX Group, he has more than 20 years of experience researching and designing commercial nonprocedural heterogeneous database processing products. Based on this experience, he has authored the book Advanced ANSI SQL Data Modeling and Structure Processing and many papers and articles on this subject. You can reach him at firstname.lastname@example.org. Additional information on hierarchical semantics and its automatic uses in SQL can be found at www.adatinc.com.