“Reduced worktime for partial service retirement” means any arrangement of worktime agreeable to both the appointing authority and the employee which aggregates no less, on a monthly basis, than a 20 percent reduction nor more than a 60 percent reduction from what would in that classification be considered full-time employment, combined with the concurrent payment of proportionally reduced compensation and proportionally reduced retirement benefits. As used in this section, and Section 19996.37, “appointing authority” means, with respect to legislative employees, the Joint Rules Committee, the Joint Legislative Budget Committee, the Joint Legislative Audit Committee, the Senate Rules Committee, and the Assembly Rules Committee.