(8) "Rule" or "rules" means a rule or regulation adopted pursuant to Chapter 13 of Title 50, the "Georgia Administrative Procedure Act."

"Rule" means any rule or regulation adopted by a board of trustees for the administration or to aid in the administration of a public retirement or pension system created by this title, except rules or regulations governing or relating to the investment of [...]

"Rule" means each agency regulation, standard, or statement of general applicability that implements, interprets, or prescribes law or policy or describes the organization, procedure, or practice requirements of any agency. The term includes the amendment [...]