Single-Level Bill of Materials (BOM) Definition
A bill of materials (BOM) is a complete listing of parts, assemblies, and other materials required to build a product. A BOM can be thought of as the recipe used to create a product. The bill of materials explains what, how, and where to buy required materials, and includes instructions for how to assemble the product from the various parts ordered.
A single-level BOM represents one level of an assemby and does not include any lower level subassemblies.
A multilevel BOM contains several subassembies, each of which can also be as single-level BOMs.