Intel XENIX 286 Programmers Guide (86) - Tenox.tc

SCCS: Source Code Control System XENIX Programming
To simplify s-file storage, all logically related files (e.g., files belonging to the same
project) should be kept in the same directory. Such directories should contain only sfiles
and should have read and search permission for everyone and write permission for
the user alone.
Note that you must not use the XENIX link command to create multiple links to an sfile.
Deltas and SIDs
Unlike an ordinary text file, an s-file contains nothing more than lists of changes. Each
list corresponds to the changes needed to construct exactly one version of the file. The
lists are combined to create the desired version from the original.
Each list of changes is called a delta. Each delta has an identification string called an
SID. The SID is a string of at least two and at most four numbers separated by periods.
The numbers name the version and define how it is related to other versions. For
example, the first delta is usually numbered "1.1" and the second "1.2".
The first number in any SID is called the release nu mber. The release number usually
indicates a group of versions that are similar and generally compatible. The second
number in the SID is the level nu mber. It indicates major differences between files in
the same release.
An SID may also have two optional numbers. The branch number, the optional third
number, indicates changes at a particular level, and the sequence number, the fourth
number, indicates changes at a particular branch. For example, the SIDs "1.1. 1.1" and
"1.1.1.2" indicate two new versions that contain slight changes to the original delta 1.1.
An s-file may at any time contain several different releases, levels, branches, and
sequences of the same file. In general, the maximum number of releases an s-file may
contain is 9999, that is, release numbers may range from 1 to 9999. The same limit
applies to level, branch, and sequence numbers.
When you create a new version, SCCS usually creates a new SID by incrementing the
level number of the original version. If you wish to create a new release, you must
explicitly instruct the system to do so. A change to a release number indicates a major
new version of the file. How to create a new version of a file and change release
numbers is described later.
SCCS creates a branch and sequence number for the SID of a new version if the next
higher level num ber already exists. For example, if you change version 1.3 to create a
version 1.4 and then change 1.3 again, the SCCS system creates a new version named
1.3.1.1.
Version numbers can become quite complicated. In general, it is wise to keep the
numbers as simple as possible by carefully planning the creation of each new version.
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