As used in sections 13-701 to 13-706, and unless otherwise clearly required by the context, the following terms have the respective meanings and connotations shown:

(1) An attack means any action or series of actions by an enemy of the United States, causing, or which may cause, substantial injury or damage to civilian persons or property in the United States in any manner, whether by sabotage, or by the use of bombs, missiles, or shellfire, or by atomic, radiological, chemical, bacteriological, or biological means, or by other weapons or processes;

(2) The term political subdivisions includes counties, townships, cities, villages, districts, authorities, and other public corporations and entities, whether organized and existing under direct provisions of the Constitution of Nebraska or statutes of this state, or by virtue of charters or other corporate articles or instruments executed under authority of such Constitution or laws; and

(3) The term seat of local government, when applied to a political subdivision, usually means the place fixed by law, charter, etc., as the situs of its separate government; as, for example, the county seat of a county. But in any instance where the law, charter, etc., does not fix a specific place therefor, then the term seat of local government means the place at which the separate government of the subdivision usually is maintained in accordance with tradition or custom.