4  Implementation

4.1  The provisions of paragraph 6 (Implementation) of Part 1 (General Provisions) shall apply.

4.2  Where the Medium Value Change:

(a)  is implemented at a Property before the Services Commencement Date, and constitutes additional or varied Works, the procedure set out at clause 20 (Certification of Services Availability) shall apply to the Works which are the subject of the Medium Value Change at the same time as the relevant Property is subject to that procedure;

(b)  is implemented at a Property after the Services Availability Date for that Property, and constitutes works, the procedure set out and agreed in the Contractor Response for certifying the completion of the Medium Value Change shall apply to determine whether the Medium Value Change has been completed appropriately.

(c)  constitutes additional or varied Services, the Payment Mechanism shall apply to determine whether the Medium Value Change has been properly implemented.