This part of ISO 18314 specifies the method for determining the colour coordinates of a paint film. This method is only applicable to paint films that appear to be uniformly of one colour, i.e. monochromatic, when examined with normal vision. Paint films that do not completely hide a non-transparent substrate represent an opaque system and can be measured by using the procedure in this part of ISO 18314. Luminescent paint films, transparent paint films, and translucent paint films (for example for display or lamp glass), retroreflecting paint films (for example for traffic signs), and metallic paint films are outside the scope of this part of ISO 18314.