There is no code, the post proc is used to convert data that makes the screen toolpaths into machine NC code specific to that machine the post is designed for,
ie. a Fanuc post processor cannot make code to run on an Okuma without having to be edited.
or... a Mastercam Okuma post cannot be used on a different CADCAM system.
( some CADCAM systems generate an intermediate file that is used to create the NC code, it is not usable to the machine or easily understood )