The means in which production is planned and controlled. There are two primary control protocols: push and pull (see Push and Pull). Push protocol is typically based on external considerations such as the schedule, desired production rate, etc. whereas the pull protocol considers the status of the system, particularly how much WIP there is in the system. Consequently, push protocols can easily overload the system resulting in excessive WIP and long cycle times. Alternatively, pull protocols avoid these problems by keeping WIP at a level to maintain good throughput with minimal cycle time. CONWIP is a general pull system that is easily implemented and effective (see CONWIP).