Notch code

A notch code is a set of notches or recesses cut into the edge of a piece of sheet film to provide a tactile way to identify the film brand, type, and processing chemistry (e.g. black and white, color negative, or color reversal) in the dark. It enables photographers to identify the emulsion side of the film when loading sheet film holders, and helps processing lab technicians avoid placing sheets in the wrong processor. After processing the notches serve as a permanent visual record of the same information. When the film is oriented vertically (portrait format), the notches are in the top edge near the upper right corner when the emulsion faces the viewer.