A bill of materials (BOM) is a detailed description of the components of a tangible or intangible product (this can be data) and their conditions of use. Much more than a simple list, it's a reference document expressing, in compact, codified form, information concerning all the company's activities. It includes descriptions of parts, drawings and other CAD (Computer-Aided Design) definitions, as well as references to specifications and regulations, and the results of finite-element calculations.
This applies to elements designed in-house, using the company's own resources, but also to products obtained from external suppliers.
Bills of material (BOMs) are a common language in every company, serving as a means of communication between technicians, whatever their specialties and geographical locations. Often considered by designers as an administrative task carried out at the last minute, when the "real" technical work is finished, nomenclature is increasingly becoming an essential task, carried out a priori and serving as a tool for steering design work.