Note 1 to entry: The concept of correlated colour temperature should not be used if the chromaticity of the test source differs more than $\text{Δ}C={\left[{\left({u^{\prime }}_{\text{t}}-{u^{\prime }}_{\text{p}}\right)}^2+\frac{4}{9}{\left({v^{\prime }}_{\text{t}}-{v^{\prime }}_{\text{p}}\right)}^2\right]}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}=5\times {10}^{-2}$ from the Planckian radiator, where ${u^{\prime }}_{\text{t}},{v^{\prime }}_{\text{t}}$ refer to the test source, and ${u^{\prime }}_{\text{p}},{v^{\prime }}_{\text{p}}$ to the Planckian radiator.

Note 2 to entry: Correlated colour temperature can be calculated by a simple minimum search computer program that searches for that Planckian temperature that provides the smallest chromaticity difference between the test chromaticity and the Planckian locus, or for example by a method recommended by Robertson, A.R. "Computation of correlated color temperature and distribution temperature", J. Opt. Soc. Am. 58, 1528-1535, 1968. (Note that the values in some of the tables in this reference are not up to date.)

Note 3 to entry: The chromaticity diagram originally used to determine the correlated colour temperature was the CIE 1960 uniform-chromaticity-scale diagram. The CIE 1976 uniform-chromaticity-scale diagram is a modified version of the CIE 1960 uniform-chromaticity-scale diagram and is equivalent to the (u, 3/2 v) diagram.

Note 4 to entry: The correlated colour temperature is expressed in kelvin (K).

Note 5 to entry: This entry was numbered 845-03-50 in IEC 60050-845:1987.

Note 6 to entry: This note applies to the French language only.