After lot-sizing, production programs are released and allocated to the production resources by resource planning. To allocate the programs optimally, capacity constraints of the resources need to be considered. While only the most important products (A products) are taken into account in lot-sizing, all products (B and C products) including products that fill up the safety stock have to be considered. Moreover, the transportation relations between process steps and set-up times of the machines are not considered explicitly in lot-sizing. Therefore, planning is performed on a rough time window (e.g. weekly basis). In contrast to lot-sizing, resource planning takes into account all relevant time consuming activities and it is performed based on a shorter time window. The objective of resource planning is scheduling the production date and process.