 WM was developed from a program called Interactive Physics, the fundamental difference between the two is that WM will read .dxf files which can be converted to 'objects' inside WM, and the way back, therefore being the conversion of Interactive Physics to the engineering and industrial world.The 3D version of Working Model is developed with the commercial name SimWise Motion also by Design Simulation Technologies, and works as a stand alone solution or an add-on for CAD products like Autodesk Inventor, SolidEdge, SolidWorks, CATIA, Alibre Design, Pro/E.Additional integration with Nastran FEA solver leads to what is called a "4D" solution with fem analysis at each integration step of the kinetodynamical simulation (Working Model 4D, later visualNastran 4D and now SimWise 4D).