Editing Color blindness (section)

===Signal lights===
{{See also|#Occupations}}
[[Navigation light]]s in marine and aviation settings employ red and green lights to signal the relative position of other ships or aircraft. [[Railway signal#Colour light signals|Railway signal lights]] also rely heavily on red–green–yellow colors. In both cases, these color combinations can be difficult for the red–green color blind. [[Farnsworth Lantern Test|Lantern Tests]] are a common means of simulating these light sources to determine not necessarily whether someone is color blind, but whether they can functionally distinguish these specific signal colors. Those who cannot pass this test are generally completely restricted from working on aircraft, ships or rail, for example.