Auditor appointment limits restrict consecutive terms for individuals and firms; a cooling-off period is required before reappointment. Rule 19 limits auditor tenure: individuals are barred from appointment or re-appointment beyond one consecutive five-year term; audit firms beyond two consecutive five-year terms. Eligibility for subsequent appointment requires a two-year cooling-off period. Periods served before these rules commenced count toward the consecutive-term limits, and 'appointment' encompasses re-appointment.