This Standard specifies the allowable colours for steady signal lights and flashing signal lights where the duration of the on period is at least one second. It is applicable to the colours of signal lights used in sea, road, air and rail transport systems including signal lights on ships, aircraft, motor vehicles and trains, where the recognition of the colours involved is essential. The Standard can also be used for guidance on the selection of the colours of light signals and warning lights on instrument panels in vehicles, of light signals and warning lights on instrument panels used for monitoring or control of industrial processes, used in visual display terminals when recognition of the colour code is important to intepreting the information displayed. The Standard does not specify how signal lights should be used in the various transport modes nor does it specify the meanings to be associated with the different colours. Reference must also be made to international, regional and national conventions and regulations for the particular applications. This Standard is not applicable to the colours of surface colour codes. Guidance on the allowable colours for surface colour codes is given in CIE Publication 39.2-1983 Recommendations for Surface Colours for Visual Signalling.