CS 31TGB.75 Warning, caution, and advisory lights
ED Decision 2013/011/R
If warning, caution or advisory lights are installed, these are:
(a) red, for warning lights (lights that indicate a condition that demands immediate corrective action);
(b) amber or yellow, for caution lights (lights that indicate a condition that requires immediate awareness and the possible need for subsequent corrective action);
(c) green, for safe operation lights; and
(d) of any other colour, including white, for lights not described in paragraphs (a) through (c) of this paragraph, provided the colour differs sufficiently from the colours prescribed in paragraphs (a) through (c) to avoid possible confusion; and
(e) visible under all likely lighting conditions.