sccsfile(4)sccsfile(4)NAMEsccsfile - 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 Arbi‐
trary 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 oper‐
ating systems usually use this same value but it may be dis‐
played or documented 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 con‐
tains 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
associated 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 pro‐
hibits 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
purpose.
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 ALSOadmin(1), delta(1), get(1), prs(1).
sccsfile(4)