Can be set on a projectile to determine the amount of cluster impacts spawned by the weapon. The cluster impacts are scattered around the main weapon impact and use the same Damage and Warhead as it does.
In Tiberian Sun and Firestorm, this flag also defines the amount of AirburstWeapon= shots to fire if the projectile has Airburst=yes set. With no AirburstWeapon= set, this defines the number of seperate explosions caused when the projectile hits. The explosions are spread in a circular pattern around the point of impact. In Red Alert 2 and Yuri's Revenge, the game instead defaults to 9 cluster explosions (or instances of the AirburstWeapon), spread in a square pattern.