For the establishment of eligible lists for appointment to positions in the Office of the Comptroller upon which lists shall be placed the names of successful candidates in order of their relative excellence in the respective examinations. The Director may establish eligible lists by numerical ratings or rankings such as superior, excellent, qualified or well-qualified. Such rules may provide for lists by area or location, for removal of those not available for or refusing employment, for minimum and maximum duration of such lists, and for such other provisions as may be necessary.