fire sac(Two mechanized companies defend in the center of the formation and have reserve positions at a depth to which they can retreat and contain the fire sac. The mortar battery is split into two platoon firing positions.4uzhoj)
internal fire sac(ru.wikipedia.org/wiki/Огневой_мешок: The Soviets almost always form internal fire sacs within their battalion and higher defensive positions, and channel the enemy attack into these sacs so that he can be destroyed by fire from three sides. • Combat outposts channel the enemy attack through a false position and into an internal fire sac.4uzhoj)
