References
American National Standards Institute
ANSI Z535.1-2006: Safety Colour Code
ANSI Z535.2-2002: Environmental and Facility Safety Signs
ANSI Z535.3-2002: Criteria for Safety Symbols
ANSI Z535.4-2007: Product Safety Signs and Labels
ANSI Z535.5-2002: Safety Tags and Barricade Tapes (for Temporary Hazards)