This name change was significant. It reflected the reality that modern systems do more than detect smoke; they signal occupants to "take action." This action could be evacuating due to a fire, sheltering in place during a weather emergency, or locking down a facility during a security threat. NFPA 72 now integrates mass notification systems (MNS), ensuring that a building's communication infrastructure can handle multiple types of emergencies.

If you hear a horn or see a strobe, this chapter governs it. Key rules include:

“That’s against code,” the man whispered, startled. “You can’t force mass notification without a verified—”