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They missed slightly on the definition of Illuminant C. It DOES have the stated correlated color temperature. However, it is not "daylight minus the UV region," but a physical approximation of daylight minus the UV region, obtained by light from an incandescent lamp of known color temperature passing through a blue chemical solution of known composition, concentration and thickness. It comes from a time when it was worthwhile to set up such a physical source rather than do the succesive multiplications wavelength by wavelength from a defined, measured daylight spectrum. The availability of computers has obsoleted the old procedure.
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