Level C - Nato SDIP-27

(formerly AMSG 784) and USA NSTISSAM Level III

Tempest Level C is also referred to as "TACTICAL". This standard applies to environments and equipment within NATO Zone 2 (where eavesdroppers are assumed to be at least 100 meters away). This standard protects equipment from 100 meters of unobstructed distance or a comparable distance through walls and obstacles.