Control Area 4 : A designated area, either indoors or outdoors, within which limited quantities of hazardous materials are allowed to be stored, used, handled, or dispensed
NFPA 318 Standard for the Protection of Semiconductor Fabrication Facilities, 2002 ed. http://www.nfpa.org/assets/files/AboutTheCodes/318 /Errata318-02-2.PDF, (Std: Prot of Semiconductor Fabrication Fcilty - Amer) {297 NFC}