 The third IDEF (IDEF2) was originally intended as a user interface modeling method.However, since the Integrated Computer-Aided Manufacturing (ICAM) Program needed a simulation modeling tool, the resulting IDEF2 was a method for representing the time varying behavior of resources in a manufacturing system, providing a framework for specification of math model based simulations.It was the intent of the methodology program within ICAM to rectify this situation but limitation of funding did not allow this to happen.