The Toyota Motor Company, which has spawned the 3rd revolution in manufacturing system design (MSD), developed the Toyota Production System. Now called Lean Production, the key proprietary aspects of this new MSD are the U-shaped manufacturing and assembly cells. Using these new cell designs, Toyota employed the concept of design decoupling to separate (decouple) the processing times for individual machines from the cycle time for the cell, permitting the lead time for a batch of parts to be independent of the processing times for individual machines. This takes all the variation out of the supply chain lead times so scheduling of the supply system can be greatly simplified and operated by a pull system of production control (kanban). Using kanban, the inventory levels can be dropped, which decreases the throughput time for the manufacturing system.