By determining reflection classes, an LC display's suitability for various work place environments and lighting conditions is specified. According to the norm, displays are subdivided into three quality categories: class I means that the device is suited for general work place environments and different kinds of lighting conditions. Whereas the suitability of class II is somewhat restricted. Here, one speaks of suitability for most of the work place environments only. Frequently changing lighting conditions can lessen the image quality in this aspect. Devices categorized in class III are suited for work place environments with controlled luminosity, which means that the lighting conditions have to be nearly constant.