In ERP systems, Low-Level Codes (LLCs) are a key concept in Manufacturing Resource Planning (MRP) that help control how materials are planned and processed, especially in complex Bills of Materials (BOMs).
What Is a Low-Level Code (LLC)?
A Low-Level Code is a number assigned to each item in an ERP system that indicates the lowest (deepest) level at which that item appears in any Bill of Materials.
Lower number = higher in the product structure
Why Low-Level Codes Matter
Low-Level Codes ensure that:
- Materials are planned in the correct sequence.
- MRP calculations are accurate.
- Demand is fully exploded before supply planning begins.
- Items used in multiple BOMs are planned only once, at the correct time
Without LLCs, ERP systems could:
- Plan components too early or too late.
- Duplicate demand.
- Create incorrect purchase or production orders
How Low-Level Codes Work (Simple Example)
BOM Structure
Level 0: Finished Product (A)
└─ Level 1: Subassembly (B)
└─ Level 2: Component (C)
| Item | Lowest Level Appears | Low-Level Code |
| A | Level 0 | 0 |
| B | Level 1 | 1 |
| C | Level 2 | 2 |
If Component C appears in another BOM at Level 3, its LLC becomes 3, the lowest level anywhere.
How ERP Systems Use Low-Level Codes in MRP
During an MRP run:
- ERP processes items level by level, starting at Level 0.
- Demand is exploded downward.
- Planning happens only after all parent demand is known.
- Each item is planned once, at its LLC
This prevents:
- Partial planning.
- Missed dependent demand.
- Reprocessing the same item multiple times
Where You’ll See Low-Level Codes in ERP
Common ERP systems that use LLCs include:
- SAP (ECC / S/4HANA) – MRP Low-Level Code.
- Oracle E-Business Suite / Oracle Cloud SCM.
- Microsoft Dynamics 365 Supply Chain Management.
- Infor LN / M3.
- NetSuite Manufacturing
Usually stored in:
- Item master records.
- MRP planning tables.
- Calculated automatically when BOMs are changed.
Key Characteristics of Low-Level Codes
- Automatically calculated by ERP.
- Rebuilt when:
- BOMs change
- New items are added
- BOMs change
- Specific to MRP, not accounting or finance
- Used only in manufacturing / supply chain modules
In One Sentence
Low-Level Codes tell the ERP system when to plan each item by identifying the lowest point it appears in any BOM, ensuring accurate and efficient MRP calculations.
