This standard is specifically designed for testing and evaluating a special category of colored textiles that undergo reversible color changes upon brief light exposure, followed by substantial restoration of their original color when stored in darkness. It aims to distinguish this temporary "photochromic" phenomenon from conventional permanent fading, providing a unified testing procedure for assessing the dynamic color stability of such textiles. To conduct this test, laboratories must use a xenon-arc lamp tester or other equivalent light exposure equipment to subject the samples to short-term illumination under standardized conditions. After testing, the degree of color change in the samples—both after light exposure and subsequent restoration in darkness—must be scientifically evaluated using a gray scale or other standard color comparison tools.