Bill of materials

A bill of materials, often shortened to BOM and also called a product structure, is the structured list of everything needed to build an end product: the raw materials, sub-assemblies, intermediate assemblies, sub-components and parts, together with the quantity of each. It can be used to communicate between manufacturing partners or kept within a single plant, and it is commonly tied to a production order, which can reserve components that are in stock and raise requisitions for those that are not. BOMs are hierarchical, with the finished product at the top and sub-assemblies below it, and a modular BOM describes one such sub-assembly. Implosion links component pieces up to a major assembly, while explosion breaks an assembly down into its parts. Variants include engineering, sales, manufacturing and service BOMs, single-level and indented BOMs, and configurable BOMs for products with many options. In electronics the BOM lists the components on a printed circuit board, and in process industries it is known as the formula or recipe.