1. (a) has become eligible for a vested retirement allowance or for a certain service retirement allowance in accordance with any of the retirement plans set forth in the Retirement and Social Security Law;
2. (b) subsequently terminates his employment with the participating employer with which he has earned such status;
3. (c) then either commences or continues employment with another participating employer which offers a retirement plan providing less favorable benefits; and

4. (d) the member then applies for service retirement;

   the member's retirement allowance shall be determined in accordance with the method set forth in the retirement plan provided by the participating employer by which he was last employed prior to retirement; provided, however, that in no event shall the retirement allowance of such a member be less than that to which the member was entitled by virtue of his status as an employee at the time he terminated his employment with the participating employer with which he had earned such status.

In the event that a member of the Retirement System: