ISO 3664 is a standard dealing with viewing conditions for graphic technology and photography. It specifies viewing conditions for images on reflective and transmissive media, such as prints, transparencies and color monitors.
The 2009 revision creates tighter requirements so that the illumination lamps in light booths must have a certain amount of UV (ultra violet) light included in order to more closely match the UV in daylight. This provision of the 2009 document took effect January 1, 2012. Since this date, all viewing booths conforming to this standard have UV-included lamps.