SAP automatically adds the material in to the planning file list once the configuration is complete and MRP types are assigned to the materials. Adding materials to be planning file does not necessarily mean that the material will be/will not be considered in the planning run. For the materials to be considered in the planning run, they should be marked on with either “net change planning option”, “net change planning in the planning horizon option” or “regenerative planning option”. These options are used to select the materials for the planning run. 

Planning all the materials included in the list would tremendously reduce the system performance and would stall it. Thus SAP provides an option to consider only those materials which have undergone a net change like an incoming order or creation of a reservation, a goods receipt for the material in a plant, or deletion of the orders or reversal/cancellation of the stock etc. This is called “Net change Planning” concept.

Though you always have an option to plan all the materials in the planning file which is called as a regenerative planning. This is usually carried out when you go-live or implement SAP for the first time. 

All the entries in the planning file will have a “change indicator” specifying that a material has undergone a change (change in receipts elements or issues elements). This indicator will help you to choose only those materials that have undergone a change, through the use of planning key called “Net Change Planning” when running MRP. 

The planning file record for a material also has a “net change planning in the current horizon” field which will be set if the change in the materials receipt or issue element is valid in the planning horizon. This indicator will help you choose only those materials which have undergone a change in the planning horizon; through the use of a planning key, in an MRP run, called “Net change planning in the planning horizon”.