As we have discussed before, all drivers (including all parts of the world) can recognize the universal symbol for STOP. It is a RED OCTAGON-shaped sign LOCATED on the side of the road at the SAME height in all locations. Granted, the sign may be on different sides of the road, based on the country you are driving in, as that country may drive on a different side of the road.
But imagine the chaos that would ensue if each local town could choose a different size, shape, and color STOP sign! This article will attempt to explain the general rules for “visual coding.”
Coding shall be used to facilitate
(1) discrimination between individual displays,
(2) identification of functionally-related displays,
(3) recognition of the relationship between displays,
(4) identification of critical information within a display, and to preserve conventional practices and arrangements for warning and alerting systems.
[Source: MIL-STD-1472G, 2012]
Visual indicators shall be coded by color, size, location, shape, or flash coding as applicable. [Source: MIL-STD-1472G, 2012]
Visual coding shall be consistent within a system or unit of equipment and between similar units of equipment. [Source: MIL-STD- 1472G, 2012]
Visual signals should be coded to indicate the priority level of the signal. [Source: MIL-STD-1472G, 2012]
Acceptable coding methods include color, position, shape, flashing, and symbol. [Source: MIL-STD-1472G, 2012]
Emergency conditions. Flashing red shall denote emergency conditions requiring immediate user action to avert impending injury, equipment damage, or both with an approximately equal on and off time flashing rate from three to five flashes per second. [Source: MIL-STD- 1472G, 2012]
Flasher failure. When an emergency condition exists and the flasher fails, the light shall illuminate and burn steadily. [Source: MIL-STD- 1472G, 2012]
If visual tiles are used, their legends shall:
a. be concise, specific, and unambiguous;
b. use abbreviations or acronyms consistent throughout the equipment or system, and
c. be legible in worst-case conditions, for example, from the far end of the room, or from a spot that maximizes glare. [Source: DOD-HFDG-ATCCS, 1992]