1.1 ,This specification is applicable to environmentally controlled dynamic glazings (ECDG) whose visible light transmittance or near infrared light transmittance properties, or both, can be changed reversibly by exposure to changing environmental conditions such as temperature and sunlight intensity. This includes thermochromic and thermotropic glazing, but currently excludes photochromic glazings as neither Test Method E3119 nor this specification provide a procedure to access multiple states of photochromic glazing specimens.