On a bill of materials, which number indicates the parts that form each sub-assembly?

In a bill of materials, the part level number is critical for identifying the specific components required for constructing each sub-assembly. This number uniquely designates each part within the broader assembly, allowing for precise tracking and management of materials.

The part level number breaks down the assembly into individual components, which is essential for manufacturers to ensure that every piece needed for assembly is accounted for. This structure aids in inventory management, procurement, and production planning.

While the other options represent various elements related to assemblies, they do not specifically refer to the identification of individual parts within sub-assemblies. For example, the assembly level number pertains to the overall assembly structure rather than its components, the sub-assembly index could refer to organizing or categorizing sub-assemblies themselves rather than their constituent parts, and the component identifier is more general and may not specifically denote the level of a part within a sub-assembly context. Hence, the part level number is the correct choice for identifying the parts that make up sub-assemblies.