A QAP is a component of the purchase plan and describes the strategy and methods deployed to ensure that the purchase and its deliverables are on track to meet client expectations. In the case of performance-based contracts, it directly corresponds to the performance standards, and it measures supplier performance. The QAP ensures that the client receives the quality called for in the contract and pays for only what is received. The QAP should include a surveillance schedule and clearly stated surveillance method(s). Surveillance can range from a one-time inspection of a product or service to periodic in-process inspections of ongoing product or service delivery. Additional discussion can be found in the Execute Quality Assurance Plan topic of the Manage Delivery and Contract Performance task of USPS Supplying Practices Process Step 5: Measure and Manage Supply.