Systemic classification
Official nomenclature: Special Sign for Works and Installations Containing Dangerous Forces
Legal anchor: Protocol I (Additional to the Geneva Conventions), Annex I, Article 16; protective obligations referenced in Article 56
Core function: Marking of civilian infrastructure whose destruction would release catastrophic forces and cause massive civilian casualties (e.g., dams, reservoirs, nuclear installations).
Historical origin and geometric logic
Codified in 1977, the special sign consists of three bright orange circles placed on a horizontal axis with precise spacing (equal to the radius). The design emphasises visibility and distinctiveness for identification from ground and air.
Tactical immunity and absolute proscription
Under Protocol I and related treaty provisions, installations marked with this sign are afforded special protective consideration. Attacking such installations, especially when it would cause catastrophic civilian harm, is prohibited and may amount to a war crime. Misuse or deceptive display is likewise unlawful.