本文件定义了色度学中使用的三种CIE标准光源:代表典型钨丝照明的CIE标准发光体A，代表相关色温约为6？的平均日光的CIE标发光体D65500？K和CIE标准光源D50，用于表示相关色温约为5？的日光000？K、 本文件包括三种光源的相对光谱功率分布值。

This document defines three CIE standard illuminants for use in colorimetry: CIE standard illuminant A for the representation of typical tungsten-filament lighting, CIE standard illuminant D65 for the representation of average daylight having a correlated colour temperature of approximately 6？500？K and CIE standard illuminant D50 for the representation of daylight with a correlated colour temperature of approximately 5？000？K. Values of the relative spectral power distribution of the three illuminants are included in this document.