This International Standard is primarily concerned with the exchange of the spectral data, which is the fundamental data behind the colour being communicated. This International Standard provides a standard format for the interchange of data between a colorimetric measurement instrument and software used to make calculations based on those measured data. A key application is in the measurement and associated recipe formulation of dyes used in the textile industry. The application can, however, be to any industry where there is a need to communicate colorimetric data, e.g. pigment formulation in plastics and paints, colour management in the graphic arts and other colour reproduction industries.