(a) “Prior service” as applied to a state member who while employed on a part-time basis became a member because of amendments of the laws governing this system or because of a change in his or her employment status to at least a half-time basis, means all state service rendered by him or her prior to the time he or she became a member.
(b) As applied to other members, “prior service” means all state service rendered by:
(1) A university member prior to August 27, 1937.
(2) A state member other than a university member, prior to January 1, 1932.
(3) A local member or school member prior to the effective date of the contract under which he or she became a member.