Prior to the completion of the works phase there is a commissioning phase during which the Contractor can accept some waste in order to test the facility. As illustrated in the diagram above, commissioning for this purpose refers only to "hot commissioning" during which waste is processed and excludes any "cold commissioning" period. The commissioning phase starts with the issuance of a Readiness Test Certificate and ends on the issuance of the Acceptance Test Certificate, i.e. after the completion of all "hot commissioning" and performance testing. Although during this stage the full service is not being provided some waste is being processed and so an appropriate payment should be made (Module 4 Part I (Payment Mechanism Principles) Section 3.5.2 sets out further details on the payment and deductions regime during the commissioning phase). The Output Specification requires that the Contractor prepares a testing and commissioning plan to detail the activities that will occur during the commissioning phase.