The formal process of accepting delivery of a deliverable or a product. Acceptance Criteria. Those criteria, including performance requirements and essential conditions, which must be met before project deliverables are accepted. A prioritised list of criteria that the final product(s) must meet before the customer will accept them; a measurable definition of what must be done for the final product to be acceptable to the customer. They should be defined as part of the Project Brief and agreed between customer and supplier no later than the project initiation stage. They should be documented in the Project Initiation Document.