BOMs

A BOM (bill of materials) is a list of part lines that together describe an assembly. Each line says “use N of part X, mounted at Y”. A PCB BOM has hundreds of lines; a top-level product BOM may have only a dozen, each pointing at a sub-assembly.

Single-level by design

BOMs in simple-plm are single-level: each BOM lists only direct children, never grandchildren. Multi-level assemblies are achieved by composition — a top-level BOM lists a sub-assembly part, and that sub-assembly has its own BOM. This keeps each YAML file readable and each change atomic.

Line fields

Field	Purpose
`part`	The child part number.
`qty`	How many. Integers for discrete parts, decimals allowed for raw material.
`unit`	Optional unit override (default is “each”).
`reference_designators`	List of board references — `["R1", "R2", "R3"]`.
`alternates`	List of equivalent parts the buyer may substitute.

How edits land

A BOM edit in the dashboard becomes a commit on a branch — usually the working branch tied to an active ECO. Once the ECO is approved, that branch merges into main.

An ECO branches off main, accumulates BOM edits as commits, then merges back when approved.

On disk

parent: ASSY-PCB-001
lines:
  - part: R-10K-0603
    qty: 4
    reference_designators: [R1, R2, R3, R4]
  - part: C-100N-0402
    qty: 12
    alternates: [C-100N-0603]

See plm boms for the CLI surface.