Apple Cinema Tools 4 - Manual (Page 231)

35mm Film
35mm film has 64 perforations per foot. Cinema Tools supports the 4-perf 35mm and
3-perf 35mm formats for all types of film lists and change lists. These are by far the most
common 35mm formats.
The 4-perf 35mm film format has 16 frames per foot. The 3-perf 35mm format does not
have a whole number of film frames in a foot (there are 21 and one-third per foot). To
avoid tracking fractions of frames, the 3-perf 35mm format is considered to have a pattern
of two 21-frame feet followed by a 22-frame foot. See
3-Perf 35mm Offsets for more
information.
Film Edge Code
To aid in locating specific film frames, film manufacturers place numbers along the edge
of the film. These key numbers (also known as latent edge code) appear when the film is
developed. For workprints, film labs can add numbers called ink numbers (also known as
Acmade numbers).
Edge code is essential to your Cinema Tools database because it makes it possible for
you to export cut lists or change lists that specify exactly where your negatives or
workprints need to be cut in order to match your digital edits.
Key Numbers
Key numbers provide both an identification number for each roll of film and an incremental
footage count number used to identify specific film frames. They often appear as both
regular text and as a bar code.
Key number
231 Appendix A Film Background Basics