CGA9RB. ANSI CAUTION SIGNS Safety Shoes Required � 14� x 10� Rigid Plastic Caution signs notify personnel and others of requirements in area and to be cautious of surroundings. Caution safety signs feature universally understood graphics for easy identification and comprehension at first glance. ANSI signs have a safety alert triangle to indicate presence of an immediate or potentially hazardous situation. Safety signs meet the new ANSI Z535 guidelines for standardization.