In all cases, the specific terms of an executed written agreement between a provider and the Department determine the rights and responsibilities of the parties, and establish the entire agreement of the parties. Purchase of service agreements shall be in such form as the Department may direct, and the Department may make use of standard forms and riders. Revisions and amendments are within the sole discretion of the Department, subject to the timely submission of information by the Provider as described in the agreement. All revisions and amendments must be in writing and signed by the parties.
10- 144 C.M.R. ch. 24, § 8