This standard stipulates the position and size of the picture formed on the film when the camera window shoots 35mm non-anamorphic picture and anamorphic picture film (horizontal picture compression ratio is 2, screen picture aspect ratio is 2.35). This standard also recommends positioning perforations for film in cameras.
GB/T 4635-2000 history
2000GB/T 4635-2000 Image area produced by camera aperture on 35mm motion-picture film-Position and dimensions