Unless otherwise clearly required by the context, as used in this act:

(a) “Unavailable” means either that a vacancy in office exists and there is no deputy authorized to exercise all of the powers and discharge the duties of the office, or that the lawful incumbent of the office (including any deputy exercising the powers and discharging the duties of an office because of a vacancy) and his or her duly authorized deputy are absent or unable to exercise the powers and discharge the duties of the office.

(b) “Emergency interim successor” means a person designated pursuant to this act, in the event the officer is unavailable, to exercise the powers and discharge the duties of an office until a successor is appointed or elected and qualified as may be provided by the constitution, statutes, charters and ordinances or until the lawful incumbent is able to resume the exercise of the powers and discharge the duties of the office.

(c) “Office” includes all state and local offices, the powers and duties of which are defined by the constitution, statutes, charters, and ordinances, except the office of governor, and except those in the legislature and the judiciary.

(d) “Attack” means any action or series of actions taken by an enemy of the United States resulting in substantial damage or injury to persons or property in this state whether through sabotage, bombs, missiles, shellfire, or atomic, radiological, chemical, bacteriological, or biological means or other weapons or methods.

(e) “Political subdivision” includes counties, cities, townships, districts, authorities, and other public corporations and entities whether organized and existing under charter or general law.