This document provides general guidance designed to help the U.S. Department of Homeland Security (DHS) Program Managers and other executives inside and outside of DHS. It is intended to provide useful information that may help personnel better understand the technologies used to maintain and support homeland security modeling and simulation (M&S) applications. It is also intended to help the relevant professional community in developing better technical specifications for homeland security modeling and simulation (M&S) applications. Contractors outside of DHS typically develop homeland security M&S applications. Often the M&S applications that are developed today are difficult to extend for new purposes, to integrate with other software systems, or to be used by persons other than the original developer or development team. Slight changes to a model or scenario may require major changes to a system and significant cost to the sponsor.