About the Authors Sanford Friedenthal is an industry leader in model-based systems engineering (MBSE) and an independent consultant. Previously, as a Lockheed Martin Fellow, he led the corporate engineering effort to enable Model-Based Systems Development (MBSD) and other advanced practices across the company. In this capacity, he was responsible for developing and implementing strategies to institu- tionalize the practice of MBSD across the company, and provide direct model-based systems engi- neering support to multiple programs. His experience includes the application of systems engineering throughout the system life cycle from conceptual design through development and production on a broad range of systems. He has also been a systems engineering department manager responsible for ensuring that systems engineering is implemented on programs. He has been a lead developer of advanced systems engineering processes and methods, including the Object-Oriented Systems Engineering Method (OOSEM). Sandy also was a leader of the industry team that developed SysML from its inception through its adoption by the OMG. Mr. Friedenthal is well known within the systems engineering community for his role in leading the SysML effort and for his expertise in model-based systems engineering methods. He has been recognized as an International Council on Systems Engineering (INCOSE) Fellow for these contri- butions. He has given many presentations on these topics to a wide range of professional and academic audiences, both within and outside the US. Alan Moore is an Architecture Modeling Specialist at The MathWorks and has extensive expe- rience in the development of real-time and object-oriented methodologies and their application in