This document provides a harmonized process and documentation requirements for the establishment of Certificates of Conformance (CoCs) used to attest the conformity of aviation, space, and defence products (e.g. assemblies, sub-assemblies, equipment and systems, parts, material) or services). It includes a CoC template and supporting instructions on how to complete it. When quoted by the customer in a contractual requirement, application of this document is mandatory. In other cases, its use is recommended, but if there is a conflict between the requirements of this document and customer or applicable statutory/regulatory requirements, the latter take precedence. Requirements for the establishment of Authorized Release Certificates (ARCs) [e.g. European Union Aviation Safety Agency (EASA) Form 1, Federal Aviation Administration (FAA) 8130-3 tag] by an external provider holding a production approval (for new aviation products; production or spares) or maintenance approval (i.e. for in service repairs, modifications, after sales maintenance, overhaul activities, inspections) are not covered by this document, as applicable rules are defined by the aviation authorities having granted these approvals.