Iff

сокращение от identification friend or foe радиолокационная система опознавания самолётов и кораблей типа "свой - чужой"

сокращение от identification friend or foe радиолокационное опознавание (государственной принадлежности) цели, опознавание цели (типа) "свой - чужой"

conjunction Etymology: alteration of ¹if if and only if Example: two figures are congruent iff one can be placed over the other so that they coincide

abbreviation identification, friend or foe

1. Interchange File Format. 2. Identify friend or foe (radar).

if and only if, i.e. necessary and sufficient. For example, two figures are congruent iff one can be placed over the other so that they coincide.