MS4 Modeling Environment (MS4 Me) is a discrete event simulation system (DEVS) software developed by MS4 Systems, Inc. It has been used in the modeling of complex systems (such as a national health care system) and is also covered in a discrete event simulation and systems of systems modeling text.MS4 Me supports the development and simulation of DEVS models via a natural language or Java. Finite Deterministic DEVS (FDDEVS) models can also be quickly developed and analyzed.