Headquartered in Alexandria, VA, Systems Definition, Inc. (SDI) provides innovative, focused software development, system planning, technical documentation, and more to the First Responder community, as well as a variety of DoD and commercial clients. Our activities support initiatives for Defense, First Responder safety and accountability, aerospace, custom applications, and web technologies. We deliver a comprehensive suite of fireground accountability applications which are used daily by fire departments across the United States, including the New York City Fire Department.