MM / P2Pintermediate

MM Purchase Requisition Part 3: MRP-Generated vs Manually Created Requisitions

Key takeaway

Understand requisitions created by MRP versus users: how MRP calculates quantities and dates, firming and changes by MRP runs, when buyers should (not) change MRP requisitions, planning time fence, and how to handle manual requisitions for non-planned items.

Explanation

📌 KEY POINTS
✅ MRP creates PRs (or planned orders converted to PRs) from net requirements, lot size and lead times.
✅ MRP deletes/recreates unfirmed PRs in later runs; changed PRs become firmed.
✅ Planning time fence protects near-term proposals from automatic changes.
✅ Manual PRs are for non-planned needs (consumables, services, one-off).
⚠️ Buyers changing MRP quantities weekly signals wrong master data, not a buyer task.

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▶ WHERE WE ARE
Part 2 covered source determination. Now PR origin.

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▶ 1. MRP PRS

Net requirements → lot size → PR with release/delivery dates.
Creation indicator in MRP run (PRs vs planned orders).

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▶ 2. FIRMING

Manually changed PRs are firmed; MRP won't change them.
Planning time fence (MRP type P1–P4).

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▶ 3. EXCEPTION MESSAGES

Reschedule in/out, cancel, start date in past (MD04).

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▶ 4. MANUAL PRS

Consumables, services, projects; not MRP-controlled.

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▶ 5. BUYER BEHAVIOR

Don't adjust MRP PRs routinely — fix lot sizes, safety stock, delivery times.

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▶ STEP BY STEP

Run MRP for a material (MD01N/MD02).
Check MD04 and the PR.
Change the PR and rerun MRP.

✅ CHECKPOINT: you can explain why MRP created, changed or deleted each PR.

Code example

ABAP Code

===== STEP 1: MRP =====MD01N / MD02 run | creation indicator: purchase requisitions in opening periodMD04 stock/requirements list: PR with exception messages ===== STEP 2: master data =====Lot size EX/FX/HB, rounding value, safety stock, planned delivery time, GR time ===== STEP 3: firming =====Manual change → firmed | MRP type with firming (time fence)

Real project scenario

Buyers reduced MRP-created PR quantities every week because lot sizes produced large orders. Reviewing lot size (FX 1,000 → EX with rounding 100) and safety stock removed the weekly manual cuts and improved inventory levels.

Common mistakes

Manually editing MRP PRs routinely.
Ignoring exception messages.
Wrong lot sizes.
No planning time fence where needed.
Manual PRs for planned materials.

Best practices

Fix MRP master data.
Review exception messages daily.
Use time fences for stability.
Reserve manual PRs for non-planned needs.
Monitor PR changes by buyers.

Interview angle

Questions: "How does MRP create PRs?", "What happens if a buyer changes an MRP PR?", "What are exception messages?"
Strong answer: net requirements, lot size, dates; firming and time fence; MD04 exceptions; manual PRs for non-planned; fix master data.

Practice this lesson

Quick check

1. Buyers reduce MRP PR quantities every week. What is the right fix?

2. Where do you see MRP exception messages for PRs of a material?

3. What happens to an MRP-generated PR that a buyer changes manually?

Interview questions

1. During hypercare of an Ariba integration project, sales order-driven procurement (third-party/drop-ship) records migrated from ECC are creating mismatched Ariba requisitions because SD-linked purchase requisition migration objects didn't carry over the sales order reference correctly. How do you troubleshoot this?

Answer it in your own words first, then compare.

2. After go-live, sales orders created for intercompany stock transfer are not triggering the expected Ariba purchase requisition flow in a hybrid SD-MM-Ariba landscape. What integration points would you check first?

Answer it in your own words first, then compare.

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Reference-verified: the steps are checked against official SAP documentation and tutorials, and object and field names in the sample code are checked for consistency. The code has not been compiled or run on an SAP system by ERPClimb. Syntax marked release-dependent varies by SAP release, so check it in your own system.