Provide at least one mode that does not require user color perception.
1. Many people are unable to distinguish between certain color combinations. Others are unable to see color at all.
2. Strategies for addressing this provision include:
a. Eliminate the need for a person see color to operate the product. This does not eliminate the use of color completely but rather requires that any information essential to the operation of a product also be conveyed in some other fashion.
b. Avoid color pairs such as red/green and blue/yellow, that are indistinguishable by people with limited color perception.
c. Provide colors with different hues and intensity so that colored objects can be distinguished even on a black and white screen by their different appearance. Depending upon the product, the manufacturer may also be able to allow users to adjust colors to match their preferences and visual abilities.
d. Avoid colors with a low luminance.
Note: virtually all Product Types and Models adhere to this Guideline, the principal exception being those products that use reversible-polarity to deliver red and green from the same LED.