For the purpose of this article, the following definitions shall apply unless the context clearly indicates or requires a different meaning.
ATTACK. Any attack or series of attacks by an enemy of the United States causing, or which may cause, substantial damage or injury to civilian property or persons in the United States in any manner by sabotage or by the use of bombs, missiles, shell fire or atomic radiological, chemical, bacteriological or biological means or other weapons or processes.
DULY AUTHORIZED DEPUTY. A person who is presently authorized to perform all of the functions, exercise all of the powers and discharge all of the duties of an office in the event the office is vacant or at such times as it lacks administration due to the death, absence or disability of the incumbent officer.
EMERGENCY INTERIM SUCCESSOR. A person designated pursuant to this article for possible temporary succession to the powers and duties, but not the office, of a city officer in the event that the officer or any duly authorized deputy is unavailable to exercise the powers and discharge the duties of the office.
UNAVAILABLE. Either 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, for physical, mental or legal reasons, to exercise the powers and discharge the duties of the office.
(`86 Code, § 7-17)