The city county planning board having four permanent seats for city residents, four permanent seats for county residents, and one seat held alternately by a city resident and a county resident, it the intent that whenever there shall be a city resident holding such rotating seat, he shall be ex officio a member of the city zoning commission, when the rotating seat is not occupied by a city resident, the mayor, with consent of the council, may appoint any city resident to serve as such fifth member of the city zoning commission. (Res. 657 § 2, 1981)