Abstract Looking for a world model for the manufacturing information flow diagram has brought us to the conclusion that it is impossible to build an all-encompassing, all-inclusive system. The redundancy and overlap would make the system excessively complex and ineffective. The best way to generalize a model of this type is to simplify. The result is that we eliminate nearly the entire production control mechanism that is found in the labour intensive MRP system (Fig. 1). We come up with a system that is much closer to the material intensive JIT system (Fig. 2). The conclusion is that effective production control requires that you choose which resource you wish to optimize, and then select a system that controls the plant around the selected resource base. This is the function of books like International Management and Production. A second conclusion would be that complexity (MRP—Fig. 1) gains very little over simplicity (JIT—Fig. 2 or World Model—Fig. 4) in productivity or efficiency. As Shozo Hibino say...