Emergency signage has long been a staple of fire safety on the industrial landscape. The general rule for facilities is that approved standard identification must mark all exits with the exception of the main entrance. In addition, listed directional exit signs (at least 6-in. high per National Fire Protection Association (NFPA) #101) must appear in every location where the direction of travel to the nearest floor exit is concealed from view from any point of occupant travel. The traditional red and white exit sign may include an arrow. Because exits vary in identity, an almost unlimited array of exit signage has evolved into those including language such as ROOF ACCESS, PUSH TO EXIT, THIS DOOR TO REMAIN OPEN WHEN THE BUILDING IS OCCUPIED, IN FIRE EMERGENCY DO NOT USE ELEVATOR-USE EXIT STAIRS, FIRE DOOR-DO NOT OBSTRUCT, IN EMERGENCY SLIDE TO OPEN, NO EXIT, AREA OF REFUGE, and so on. Exit signs are typically illuminated and must be visible from any direction of exit access.