87.108. Where the agreement becomes null or is terminated pursuant to section 87.107 or because of circumstances provided for in the regulations made under the Act respecting the Government and Public Employees Retirement Plan (chapter R-10), the Act respecting the Teachers Pension Plan (chapter R-11), the Act respecting the Civil Service Superannuation Plan (chapter R-12), the pensionable salary, the service credited and the contributions to the retirement plan shall be determined, for each of the circumstances, in the manner prescribed by those regulations as they read on the date on which they are applied.