A notching code refers to a series of shaped cuts along the edge of sheet film that identify the specific type of film being used. These distinctive patterns allow photographers to recognise different film stocks by touch, which is especially important when working in complete darkness in a darkroom.
Each manufacturer uses unique notching patterns to distinguish between film types, speeds, and emulsions. This system helps prevent mistakes during loading, processing, and development, ensuring that the correct handling and exposure techniques are applied to each sheet of film.