sccsfile — format of SCCS file
An SCCS file is an ASCII file consisting of six logical parts:
Sum of all characters in the file except the first line.
- delta table
Contains information about each delta.
- user names
Login names and/or numerical group
of users who are allowed to add deltas.
Definitions of internal keywords.
Arbitrary descriptive information about the file.
Actual text lines intermixed with control lines.
Throughout an SCCS
file there are lines beginning with the ASCII SOH
(start of heading) character (octal 001).
This character is hereafter referred to as the
and is represented graphically as
Any line described below that is not depicted as beginning
with the control character is prevented
from beginning with the control character.
All lines in the SCCS file are limited to
characters in length.
Entries of the form
represent a five-digit string (a number between 00000 and 99999).
The following describes each logical part of an
The checksum is the first line of an
The form of the line is:
The value of the checksum is the sum of all characters except
those in the first line.
sequence provides a
consisting of the two bytes 0x01 and 0x68.
(Other versions of UNIX-like operating systems usually use this same value
but it may be displayed or documented as a single number with a different
- Delta table
The delta table consists of a variable number of entries of the form:
@d <type> <SID> yr/mo/da hr:mi:se <pgmr> DDDDD DDDDD
@i DDDDD ...
@x DDDDD ...
@g DDDDD ...
@m <MR number>
@c <comments> ...
The first line
contains the number of lines
The second line
contains the type of the delta
(SCCS ID) of the delta,
the date and time when the delta was created,
the login name corresponding to the real user
at the time the delta was created, and the serial numbers
of the delta and its predecessor, respectively.
contain the serial numbers of deltas included,
excluded, and ignored, respectively.
These lines are optional.
lines (optional) each contain one
number associated with the delta;
lines contain comments associated with the delta.
line ends the delta table entry.
- User names
The list of login names and/or numerical group
of users who are allowed to add deltas to the file, separated by new-lines.
The lines containing these login names and/or numerical group
are surrounded by the bracketing lines
An empty list allows anyone to make a delta.
Any line starting with a
prohibits the specified group or user from making deltas.
Keywords used internally (see
for more information on their use).
Each flag line takes the form:
@f <flag> <optional text>
The following flags are defined:
@f t <type of program>
@f v <program name>
@f i <keyword string>
@f m <module name>
@f f <floor>
@f c <ceiling>
@f d <default-sid>
@f l <lock-releases>
@f q <user defined>
@f z <reserved for use in interfaces>
The above flags function as follows:
Defines the replacement for the
Controls prompting for
numbers in addition to comments.
If the optional text is present, it defines an
number-validity checking program.
Controls the warning/error aspect of the ``No id keywords'' message.
flag is not present, the message is only a warning; when the
flag is present, this message causes a fatal error (a
on the file fails, or the delta is not made).
flag is present, the
keyletter can be used on the
command to cause a branch in the delta tree.
Defines the first choice for the replacement text of the
Defines the ``floor'' release;
the release below which no deltas can be added.
Defines the ``ceiling'' release;
the release above which no deltas can be added.
Defines the default
to be used when none is specified on a
to insert a ``null'' delta (a delta that applies
changes) in those releases that are skipped when a delta is made in a
release (such as, when delta 5.1 is made after delta 2.7, releases 3 and
4 are skipped).
The absence of the
flag causes skipped releases to be completely empty.
concurrent edits of the same base
of releases that are
against editing (
Defines the replacement for the
Used in certain specialized interface programs.
Arbitrary text is surrounded by the bracketing lines
The comments section typically contains a description of the file's purpose.
Consists of text lines and control lines.
Text lines do not begin with the control character;
control lines do.
There are three kinds of control lines:
The digit string is the serial number corresponding to the delta for the
SCCS files can be any length,
but the number of lines in the text file itself cannot exceed 99,999 lines.