Abstract We consider three well-known production-inventory control systems: Material Requirements Planning, Just-In-Time and Bottleneck Scheduling. Each system was developed with a specific production environment in mind, and it would therefore be naive to assume that these systems apply to any situation. Most factories would benefit from a hybrid system which carefully weighs functionalities from different systems to fit the problem at hand. In this paper we discuss functionalities required from production-inventory control systems, and show how the three generic systems mentioned above satisfy these requirements. We then proceed by suggesting the core characteristics of a hybrid system.