During an MRP run, backward scheduling is used to calculate the basic dates for procurement proposals (like planned orders or purchase requisitions) for components. This process starts from the component's requirement date.

For components that are produced internally (in-house), the system uses the In-house production time defined in the material master (MRP 2 view) to calculate the basic start date of the planned order.

For components that are procured externally, the system uses the Planned delivery time, also from the material master (MRP 2 view), along with the goods receipt processing time, to determine when the purchase requisition must be converted into a purchase order.

B. Total replenishment lead time: This is a more general time used primarily for the availability check (ATP) and is not the specific element used by MRP for basic date scheduling.

C. Operation duration: This is used in detailed scheduling (lead time scheduling), which calculates precise production dates based on routings, not for calculating the high-level basic dates.

1. SAP S/4HANA Help Portal

"Scheduling for External Procurement": "In basic date scheduling

the system uses the planned delivery time from the material master record or purchasing info record and the goods receipt processing time from the material master record." (This supports option A).

2. SAP S/4HANA Help Portal

"Scheduling for In-House Production": "In basic date scheduling

the system always calculates the basic dates using the in-house production time that has been entered in the material master record." (This supports option D).

3. SAP S/4HANA Help Portal

"Basic Date Scheduling vs. Lead Time Scheduling": This document distinguishes the two methods

clarifying that basic date scheduling uses times from the material master (in-house production time

planned delivery time)

while lead time scheduling uses detailed data from the routing (like operation durations). (This supports the exclusion of option C).