Low-Level Code
Definition
A low-level code is a number assigned to each item identifying the lowest level at which it appears in any bill of material, used by MRP to ensure an item's requirements are fully accumulated before its needs are calculated.
In Practice
The same component often appears at different depths in different products — a bearing might be level 1 in a spares kit and level 3 inside a gearbox. MRP processes level by level, so it must not plan the bearing until every parent that uses it has been exploded; the low-level code (the deepest level of appearance, here 3) tells the system to wait until then.
Without low-level coding, MRP would plan the bearing at level 1, then discover more requirements at level 3 and have to re-plan — or worse, order twice. ERP systems compute low-level codes automatically whenever BOMs change; planners mostly meet them when diagnosing why MRP processes items in the order it does.
Frequently Asked Questions
Why does MRP need low-level codes?
MRP nets and plans one BOM level at a time. If an item appears at several depths across products, planning it too early would miss demand still waiting to be exploded from deeper parents. The low-level code makes MRP defer the item until all its parent requirements have accumulated.
How are low-level codes maintained?
The ERP system recalculates them automatically when bills of material are added or changed, scanning every structure an item appears in and recording the deepest level. Planners never set them manually, but a corrupted or unrefreshed low-level code file can cause double-ordering or missed requirements.
Related Terms
A multilevel bill of material is the complete product structure showing every level of assembly — from the finished item through subassemblies down to purchased components and raw materials — with quantities linking each parent to its children.
Material Requirements Planning (MRP)Material Requirements Planning (MRP) is a calculation engine that translates a production schedule into time-phased requirements for every component and raw material, using bills of materials, inventory records, and lead times.
Where-Used ListA where-used list is a report showing every parent assembly and product in which a given component appears, tracing the bill of material upward — the reverse of a BOM explosion.
Vertical DependencyVertical dependency is the parent-child relationship between levels of a bill of material: demand for a parent item directly creates demand for the components beneath it, cascading down through every BOM level.