Old planning and scheduling systems (such as MRP, or manufacturing resource planning) use a linear, step by step method to allocate material and production capacity. This approach is basic and cumbersome, does not easily adapt to changes in demand, resource capacity or material availability. Materials and capacity are considered separately, and many applications do not even take into account limited material availability or capacity constraints. Of course, this approachcan result in plans which can not even be executed in the real world.

More modern planning scheduling systems simultaneously plan and schedule plant production based on both available materials and capacity. This creates a more realistic production plan. To come up with a realistic production plan requires real-time access to data, total asset visibility, performance metrics and automated decision-support tools in the form of planning and scheduling software.