David Hay has been producing data models to support strategic and requirements planning since the mid-1980s. He is the founder and president of Essential Strategies, Inc., a consulting firm dedicated to helping clients define corporate information architecture, identify system requirements and plan strategies for the implementation of new systems. Hay is the author of Data Model Patterns: Conventions of Thought and Requirements Analysis: From Business Views to Architecture. He may be reached at dmr@essentialstrategies.com or by phone at (713) 464-8316.