1.1 These test methods cover the measurement of the reflection characteristics responsible for the glossy appearance of high-gloss surfaces. Three test methods, A, B and C, are provided for evaluating such surface characteristics at specular angles of 30 ° , 20 ° and 30 ° , respectively. These test methods are not suitable for diffuse finish surfaces nor do they measure color, another appearance attribute. 1.2 As originally developed by Tingle and others (see Refs 1 and 2 ), the test methods were applied only to bright metals. Recently they have been applied to high-gloss automotive finishes and other nonmetallic surfaces. 1.3 The DOI of a glossy surface is generally independent of its curvature. The DOI measurement by this test method is limited to flat or flattenable surfaces.