sccsfile(4) Kernel Interfaces Manual sccsfile(4)
NAME
sccsfile - format of SCCS file
DESCRIPTION
An SCCS file is an ASCII file consisting of six logical parts:
checksum 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 IDs of users who are allowed to add deltas.
flags Definitions of internal keywords. comments Arbitrary descriptive information about the file.
body 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 (defined in characters in length.
Entries of the form DDDDD represent a five-digit string (a number between 00000 and 99999).
The following describes each logical part of an SCCS file detail:
Checksum The checksum is the first line of an SCCS file. The form of the line is:
The value of the checksum is the sum of all characters except those in the first line. The 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 doc-
umented as a single number with a different byte order.)
Delta table
The delta table consists of a variable number of entries of the form:
.
.
.
.
.
.
The first line contains the number of lines inserted/deleted/unchanged, respectively. The second line contains the type of the
delta (currently, normal: and removed: the SID (SCCS ID) of the delta, the date and time when the delta was created, the login name
corresponding to the real user ID at the time the delta was created, and the serial numbers of the delta and its predecessor,
respectively.
The and lines contain the serial numbers of deltas included, excluded, and ignored, respectively. These lines are optional.
The lines (optional) each contain one MR (modification request) number associated with the delta; the lines contain comments associ-
ated with the delta.
The line ends the delta table entry.
User names
The list of login names and/or numerical group IDs 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 IDs are surrounded by the bracketing lines and An empty list allows anyone
to make a delta. Any line starting with a prohibits the specified group or user from making deltas.
Flags Keywords used internally (see admin(1) for more information on their use). Each flag line takes the form:
The following flags are defined:
The above flags function as follows:
Defines the replacement for the
identification keyword.
Controls prompting for
MR numbers in addition to comments. If the optional text is present, it defines an MR number-validity checking program.
Controls the warning/error aspect of the ``No id keywords'' message.
When the flag is not present, the message is only a warning; when the flag is present, this message causes a fatal error (a get on the
file fails, or the delta is not made).
When the
flag is present, the keyletter can be used on the get command to cause a branch in the delta tree.
Defines the first choice for the replacement text of the
identification keyword.
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
SID to be used when none is specified on a get command.
Causes
delta to insert a ``null'' delta (a delta that applies no changes) in those releases that are skipped when a delta is made in a new
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.
Causes
get to allow concurrent edits of the same base SID. See admin(1) for restrictions.
Defines a
list of releases that are locked against editing (get(1) with the keyletter).
Defines the replacement for the
identification keyword.
Used in certain specialized interface programs.
Comments
Arbitrary text is surrounded by the bracketing lines and The comments section typically contains a description of the file's pur-
pose.
Body 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:
insert
delete
end
The digit string is the serial number corresponding to the delta for the control line.
WARNINGS
SCCS files can be any length, but the number of lines in the text file itself cannot exceed 99,999 lines.
SEE ALSO
admin(1), delta(1), get(1), prs(1).
sccsfile(4)