Editing IDEF (section)

=== IDEF2 and IDEF3 ===
{{main|IDEF3}}
[[File:2-03 Example of an Enhanced Transition Schematic.jpg|thumb|240px|Example of an enhanced transition schematic, modelled with [[IDEF3]]]]

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 [[Integrated Computer-Aided Manufacturing|ICAM]] to rectify this situation but limitation of funding did not allow this to happen. As a result, the lack of a method which would support the structuring of descriptions of the [[user view]] of a system has been a major shortcoming of the IDEF system. The basic problem from a methodology point of view is the need to distinguish between a description of what a system (existing or proposed) is supposed to do and a representative simulation model that predicts what a system will do. The latter was the focus of [[IDEF2]], the former is the focus of [[IDEF3]].<ref name="FB89">Patricia Griffith Friel and Thomas M. Blinn (1989). [https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19910023489_1991023489.pdf "Automated IDEF3 and IDEF4 Systems Design Specification Document"]. Technical report. NASA Johnson Space Center.</ref>