### 5.3 The Body

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 (jay@gnu.org) know.