Test negatives are made with over, normal and under exposure. In addition, the printer has a set of buttons that control density and color. One bank, those that control density, are intended to compensate for back lighting and etc. These also have labels similar to the above. On the old Kodak machines they were Plus, normal plus, normal, normal minus, and minus. This gave the operator a range of 5 exposures, and using the control negative set the normal in the middle.