Ed Seidewitz has 30 years of professional experience with the modeling, architecture and development of systems spanning diverse domains including aerospace, finance, acquisition and health care. In 2009, his 2003 paper "What Models Mean" was named an IEEE Software magazine 25th Anniversary Top Pick. Mr. Seidewitz has been active with the Object Management Group (OMG) for 15 years, including involvement in every UML 2 Revision Task Force, as well as the Service Oriented Architecture Modeling Language (SoaML) and System Engineering Modeling Language (SysML) specifications. He was primary author of the Foundational Subset for Executable UML Models (fUML) and Action Language for Foundational UML (Alf) specifications. He is currently chair of the fUML and Alf Revision Task Forces, a member of the UML and Precise Semantics of UML Composite Structures Revision Task Forces and leader of the Precise Semantics of UML State Machines submission team. He is also the developer of the open source Alf Reference Implementation and the Alf plugin for MagicDraw.