What Is Low-Level Code?
Also known as: LLC, MRP level, BOM level code, planning level
Definition
A low-level code is the lowest (deepest) level at which an item appears in any bill of materials. MRP uses it to decide planning order, so each item is netted only after all demand from every parent has been calculated.
Low-Level Code Explained
Finished goods are level 0, their direct components are level 1, and so on. An item that appears at different depths in different bills of materials takes the deepest level as its low-level code. MRP processes level 0 first, then level 1, and so forth, so by the time a component is netted all of its parents have already generated their requirements.
Without low-level codes, a shared component could be netted early, before a deeper parent created further demand, and the plan would need another pass. With them, one pass per level is enough, which is why level-by-level planning scales to large product structures.
Low-level codes are maintained by the system, either on BOM change or by a batch process. When BOM edits do not refresh the codes, or the recalculation is skipped, MRP may under-plan shared components. Some systems calculate levels dynamically on each run, while others store them on the item record and need an explicit update step.
Common causes of surprises include circular BOM references, which prevent a valid level from being assigned, and frequent reuse of a part at many levels, which pushes it deep and delays its planning. Cleaning up such structures usually shortens planning runs.
Why It Matters
- Stale levels cause missing requirements for shared components with no obvious error.
- It explains why a part used at a deep level is planned last no matter where else it appears.
- Circular references are caught during level assignment, making it a useful BOM integrity check.
- Flat, well-structured BOMs have fewer levels and faster planning runs.
In Practice
Example: a gasket is used directly in a finished pump at level 1 and also inside a seal kit that sits at level 2 of the same pump. Its low-level code is 3. MRP will not net the gasket until both the pump and the seal kit have generated their requirements.
Frequently Asked Questions
How is the low-level code calculated?
By finding the deepest level at which the item appears across all active bills of materials, starting from finished goods at level 0.
When does the low-level code change?
When a BOM is added, removed or restructured so the item appears at a different depth. Some systems update immediately, others need a recalculation job.
Can a bad low-level code break MRP?
Yes. If an item is netted before all its parents are planned, MRP can under-plan its requirements, and the shortage appears only after a second run.
Related Terms
BOM (Bill of Materials)
A BOM (bill of materials) is the structured, hierarchical list of components, sub-assemblies, and quantities required to produce one unit of a parent item, and it is the primary input MRP explodes to calculate material requirements.
BOM Explosion
BOM explosion is the step in which MRP expands each parent item's planned quantity into dependent component requirements using the bill of materials, quantity-per factors, scrap and yield allowances, and effectivity dates, level by level.
MRP (Material Requirements Planning)
MRP (Material Requirements Planning) is the ERP calculation that explodes demand through bills of materials, nets it against on-hand and on-order inventory, and offsets by lead time to produce timed purchase and work order suggestions.
Gross-to-Net Requirements
Gross-to-net is the core MRP calculation. It takes gross requirements for an item in each time bucket, subtracts projected on-hand inventory and scheduled receipts, adds safety stock, and leaves the net requirement that must be covered by new planned orders.
Go Deeper
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Infor LN MRP Planning Configuration Guide
Configure MRP planning in Infor LN with planning parameters, order policies, safety stock rules, and demand pegging for optimal material requirements.
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