1.1 This practice describes the instrumental determination of retroreflected chromaticity coordinates of retro- reflectors. It includes the techniques used in a photometric range to measure retroreflected (nighttime) chromaticity with either a telecolorimeter or telespectroradiometer. 1.2 This practice covers the general measurement procedures. Additional requirements for specific tests and specifications are described in Section 7. 1.3 The description of the geometry used i