• to specify a colour match, three independent variables are necessary and sufficient,
• for an additive mixture of colour stimuli, only their tristimulus values are relevant, not their spectral compositions,
• in an additive mixture of colour stimuli, if one or more components of the mixture are gradually changed, the resulting tristimulus values also change gradually

Note 1 to entry: Grassman's laws do not hold for all observing conditions.

Note 2 to entry: This entry was numbered 845-03-17 in IEC 60050-845:1987.