This document specifies different methods of calculating special indices, which are generally used to describe lightness respectively jetness of samples including chroma or hue within one colourcoordinate. This document is applicable to tristimulus values and chromaticity coordinates calculated using colourmatching functions of the CIE 1964 standard colourimetric system. It is used for the specification of colour stimuli perceived as belonging to a reflecting or transmitting object where a one-dimensional value is required.