Lesson 4 of 5
Source lists and source determination
9 min
Contoso can buy rotors from Lakeside Components and, in emergencies, from a second supplier. Which supplier should the system propose? Should anyone be allowed to buy from a supplier that is not approved? Source lists answer both questions. A source list defines the allowed (and disallowed) sources of supply for a product in a plant over time.
What a source list entry contains
| Field | Meaning |
|---|---|
| Validity period | From and to dates for the entry |
| Supplier and purchasing org | The source; alternatively an outline agreement (contract or scheduling agreement) and item |
| Procurement plant | Optional plant that supplies instead of an external supplier |
| Fixed indicator | Marks the preferred source for the period; it is proposed first |
| Blocked indicator | The source may not be used in this period |
| MRP indicator | Whether MRP may use this source when it creates requisitions or schedule lines automatically |
Source list fields. Exact field labels vary between GUI and Fiori.
Source lists are created manually (ME01 or the Manage Source Lists app), generated automatically from info records and outline agreements (ME05 or the Generate Source List app), or added from an info record or contract item. ME06 analyzes source lists, and ME0M lists them by product.
| Rotor sources at plant 1710 | Valid | Fixed | Blocked | MRP |
|---|---|---|---|---|
| Lakeside Components, contract 4600000011 | Jan 1–Dec 31 | Yes | No | Relevant |
| Second supplier (emergency) | Jan 1–Dec 31 | No | No | Not relevant |
| Former supplier | Jan 1–Dec 31 | No | Yes | Not relevant |
Source list requirement
A source list only enforces anything if it is required. The requirement can be set for a plant in configuration or for an individual product in its purchasing view. When it is required, a PO for that product and plant must use a source that has a valid, unblocked entry. Contoso requires source lists for all production components and leaves them optional for consumables.
How source determination finds a supplier
When a requisition is created without a supplier, or a buyer asks for source assignment, SAP looks for possible sources. Simplified, it checks quota arrangements first, then the source list (preferring the fixed entry), and then outline agreements and info records, with regular supplier settings also influencing the proposal. If exactly one valid source is found, it can be assigned automatically; if several are found, the buyer chooses.
- Is there a valid quota arrangement?Yes → the supplier with the lowest quota rating is proposed · No → next check
- Is there a source list entry marked fixed for the date?Yes → the fixed source is proposed · No → next check
- Are there valid, unblocked source list entries, agreements or info records?Yes → one is assigned or the buyer chooses · No → no source; buyer must find one
- Is the source list required for this product and plant?Yes → only listed, unblocked sources are allowed · No → other sources are allowed
Keep source lists current. Expired entries quietly stop proposals, and MRP then creates requisitions without a supplier. Many teams schedule a monthly check of entries expiring in the next 60 days.
The Fiori app Manage Sources of Supply shows source lists, contracts and info records for a product together, which makes it a good review screen for buyers. Public Edition customers use these Fiori apps rather than the GUI transactions; Private Edition and on-premise users can use both.
What would you do?
After a planning run, rotor requisitions in plant 1710 have no supplier assigned, although Lakeside is the agreed source. What is the most likely cause?
- Source lists define allowed, fixed and blocked sources per product and plant over time.
- They only enforce rules when a source list is required for the plant or product.
- Source determination considers quota arrangements, fixed entries, agreements and info records.
- Expired or non-MRP entries lead to requisitions without a supplier.
Check your understanding · not graded
Lesson check
1. What does the fixed indicator on a source list entry mean?
2. Which transaction creates source list entries manually?
3. When does a source list actually restrict purchasing?
4. What tool splits demand by percentage between suppliers?