The Retirement and Social Security Law provides that members of the Retirement System become eligible under certain circumstances for a vested retirement allowance, or for a particular service retirement allowance for service credited in a specified retirement plan. However, some members of the Retirement System, having become eligible for such benefits, subsequently terminate their employment with the participating employer in whose employ they have established such eligibility, and then either commence or continue in the employ of a different participating employer which offers its employees a retirement plan which provides less favorable benefits. When such a member of the Retirement System then applies for retirement, his retirement allowance is determined in accordance with the retirement plan of the employer by which he was last employed. Since it would be inequitable, and inconsistent with the intent of the Legislature, to provide such a member with a retirement allowance which is less than that to which he was entitled by virtue of his eligibility at the time he terminated his employment with the participating employer with which he had earned such status, and since sections 11 and 311 of the Retirement and Social Security Law permit the State Comptroller to adopt and amend rules and regulations for the administration of the New York State Employees's Retirement System and the New York State Policemen's and Firemen's Retirement System, the following method of determining a member's retirement allowance in such circumstances is hereby promulgated.