One of the main settings for the MRP planning run within SAP is the Processing Key. This setting is the main indicator for which the MRP planning run will execute. There are three processing keys to choose from are net change planning (NETCH), net change planning in the planning horizon (NETPL), and online regenerative planning (NEUPL). So the usual question on this option is when is it best to utilize each of the options?
Net change planning (NETCH) is where the MRP planning run checks the planning file and executes for only those materials with the net change indicator. This is used on your more frequent planning runs as it only runs on planning file entries with the net change indicator, thus being a very efficient planning run. Typically this is used as your nightly planning run so that it runs quickly to afford other programs within your organization to also complete in off hours.
Net change planning run in the planning horizon (NETPL) works the same way as the net change planning but it is limited to the planning horizon. The planning horizon is configured at the plant level, or if you are using MRP Groups, then it can be set there as well. The planning horizon is the number of days for which MRP will consider requirements for planned replenishments. Therefore this type of planning run should execute faster than the net change for it is limited to those materials to be planned within that planning horizon range. For any long cycle time products, this is not a recommended setting.
The final processing key is the online regenerative planning (NEUPL). This is usually known as a “regen”, meaning a regeneration planning run. This is useful to run periodically, weekly or monthly, so that all planned orders are replaced with a more up to date planning situation. Regeneration planning will ignore the net change indicators and run against the entire planning file. One of the best reasons for this processing type is that it will eliminate those planned orders that have “aged in place”. Aging in place is where planned orders that had not had any further net change indicators being set after it had been planned.
These explanations for the processing keys should help clarify the differences a little better than is found in the standard SAP F1 help. This is additional information you can utilize for own organizations documentation of the MRP planning run.