The body of an sccs file is usually much longer than its header, but contains fewer ingredients. It contains control lines, which signal the beginning or end of a chunk of user data, and the user data itself. If, for example, you added the text ‘I was here’ to the controlled file as a delta whose delta sequence number was 7, the history might contain these lines:-
^AI 7 I was here ^AE 7
I currently have no clear understanding of the interaction of excluded, included or excluded revisions with the normal check-in processing. Hence I can't thoroughly explain the precise meaning of the ‘^AI’, ‘^AE’ and ‘^AD’ control lines. This section will be completed at a future date. If you have an understanding of these issues, please let me (email@example.com) know.