A client part number (CPN) is an identifier that each company assigns to an individual manufacturing part number (MPN). The CPN is your company’s part number, which must be unique to your company’s part library. Using a CPN when referring to electronic components ensures that each part is easier to sort, filter, and categorize.
Companies reference an MPN with a different CPN because there is no guarantee that two 3rd party manufacturers won’t have the same part numbers for their respective parts. For example, CompanyA refers to MPN123, while Company B refers to MPN123 as CPN789. As a result, company B’s CPN becomes a unique language for referring to parts on their bill of materials allowing for quick sourcing and identification of electronic components.