Blue–green distinction in language being described. For example, "blue" and "green" might be distinguished, but a single term might be used for both if the color is dark. Furthermore, green might be associated with yellow, and blue with black or gray. According to Brent Berlin and Paul Kay's 1969 study "", distinct terms for brown, purple, pink, orange and grey will not emerge in a language until the language has made a distinction between green and blue. In their account of the development of color terms the first terms to emerge are those for white/black (or light/dark), red and green/yellow. The word for blue
Road signs in the United Kingdom patch may only be coloured blue or green. Signs indicating a temporary change, such as roadworks or route diversions, are denoted with a yellow background. Usually these signs use a simple black on yellow colour code, more complex signage use the conventional signs superimposed onto a yellow background. In some areas, such as the Dartmoor National Park, additional signs and colours are used to distinguish road conditions. In addition to the national colour schemes, the park also uses white signs with a light blue border and text to denote routes suitable for medium-sized vehicles and white signs with a brown