(a) Subject to the consent of the board of trustees and effective for the period and on terms that the board approves, a subdivision may adopt a special service retirement eligibility provision that relates to a singular, identifiable event or action particular to the subdivision and that applies only to its members who satisfy the specific terms of the special eligibility provision.
(b) A special service retirement eligibility provision must bear a rational relationship to the operation, management, and function of the subdivision.

(c) A special service retirement eligibility provision may not be adopted or implemented under this section in a manner that has the effect of establishing a separate, ongoing retirement program for a branch, department, division, employee occupational group, or other separately identifiable component of the subdivision.