The following words and phrases when used in this act shall have, unless the context clearly indicates otherwise, the meanings given to them in this section:
"Actuarially sound plan." A plan operated under supervision of an actuary and which is being funded annually at a level not lower than the normal cost of the plan plus amortization of the unfunded accrued liability within an established period of time after the effective date of the act creating the system.
"Commission." The Public Employee Retirement Commission created pursuant to this act.
"Public Employee Retirement Plan." Any of the following:
(1) State Employees' Retirement System created pursuant to 71 Pa.C.S. Part XXV. (2) Public School Employees' Retirement System created pursuant to 24 Pa.C.S. Part IV. (3) Municipal Retirement System created pursuant to the act of February 1, 1974 (P.L. 34, No. 15). (4) Any other independent pension or retirement plan for public officers and employees in the Commonwealth.(5) Pension or retirement plans created pursuant to the act of June 23, 1931 (P.L. 932, No. 317), known as "The Third Class City Code." (6) Pension or retirement plans created pursuant to the act of May 29, 1956 (1955 P.L. 1804, No. 600), referred to as the Municipal Police Pension Law. 1981, July 9, P.L. 208, No. 66, § 3, imd. effective. Amended 1991, Dec. 20, P.L. 393, No. 42, § 1, imd. effective.