Significance and Use 5.1 The results of this test method are used to assess conformance of retroreflective sheeting to the nighttime color requirements of industry standards and government regulations, such as Specification D4956 and U.S. Code of Federal Regulations Title 23 Part 655 Subpart F. 5.2 Requirements in specifications referring to this test method are for the chromaticity of the material as viewed at night. These requirements are generally stated using four or five corner points that form a box that limits the range of acceptable chromaticity. Most of these specifications are categorical in nature; they describe a small range of colors that are recognizable from a color naming or coding purpose 5.3 The method for compliance with the specification is to plot the measured (x, y) values and determine if the measured point falls within the specification box for the color of interest.Scope 1.1 This test method describes the instrumental determination of the nighttime retroreflected chromaticity coordinates of retroreflective sheeting. 1.2 This method includes a procedure based on tristimulus filter colorimetery and a procedure based on spectral measurements. 1.3 A single set of test geometries (using 0.33° observation angle and 5° entrance angle) and apertures are described in this method. 1.4 The resulting chromaticity coordinates are for use with the CIE 1931 chromaticity system utilizing CIE Illuminant A. 1.5 If measurements and calculations are required for other sources of illumination, or geometries, or other materials, the user is referred to the general practice described in Practice E811. 1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
