<unk> : Standard System for the Identification of the Hazards of Materials for Emergency Response" is a standard maintained by the U.S.-based National Fire Protection Association. First "tentatively adopted as a guide" in 1960, and revised several times since then, it defines the colloquial "Safety Square" or "Fire Diamond" used by emergency personnel to quickly and easily identify the risks posed by hazardous materials. This helps determine what, if any, special equipment should be used, procedures followed, or precautions taken during the initial stages of an emergency response.
NFPA 704
VIR-576
CURB-65
FAST 
AP-7 
ARCT-154
PC3
C-KAD