rcsfile
RCSFILE(5) File Formats Manual RCSFILE(5)
NAME
rcsfile - RCS file format
DESCRIPTION
An RCS file's contents are described by the grammar below.
The text is free format: space, backspace, tab, newline, vertical tab,
form feed, and carriage return (collectively, white space) have no sig-
nificance except in strings. However, white space cannot appear within
an id, num, or sym, and an RCS file must end with a newline.
Strings are enclosed by @. If a string contains a @, it must be dou-
bled; otherwise, strings can contain arbitrary binary data.
The meta syntax uses the following conventions: `|' (bar) separates al-
ternatives; `{' and `}' enclose optional phrases; `{' and `}*' enclose
phrases that can be repeated zero or more times; `{' and '}+' enclose
phrases that must appear at least once and can be repeated; Terminal
symbols are in boldface; nonterminal symbols are in italics.
rcstext ::= admin {delta}* desc {deltatext}*
admin ::= head {num};
{ branch {num}; }
access {id}*;
symbols {sym : num}*;
locks {id : num}*; {strict ;}
{ integrity{intstring}; }
{ comment {string}; }
{ expand {string}; }
delta ::= num
date num;
author id;
state {id};
branches {num}*;
next {num};
{ commitid sym; }
desc ::= desc string
deltatext ::= num
log string
text string
num ::= {digit | .}+
digit ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
id ::= {idchar | .}+
sym ::= {idchar}+
idchar ::= any visible graphic character except special
special ::= $ | , | . | : | ; | @
string ::= @{any character, with @ doubled}*@
word ::= id | num | string | :
intchar ::= any character, except @
thirdp ::= ^L {intchar}*
intstring ::= @ {intchar}* {thirdp}* @
In releases prior to 5.8 (2011-08-30), the grammar included the new-
phrase production and used it in the admin, delta and deltatext produc-
tions. This allowed third-party programs to interoperate with RCS by
storing opaque (to RCS) data in the file. As of 5.8, in the name of
progress (towards more systematic file integrity support), the only
area reserved for third-party interop is in the (string) value of the
integrity field, specifically after the first ^L (formfeed). A further
restriction (for all programs) is that the integrity value must not
contain @.
Identifiers are case sensitive. Keywords are in lower case only. The
sets of keywords and identifiers can overlap. In most environments RCS
uses the ISO 8859/1 encoding: visible graphic characters are codes
041-176 and 240-377, and white space characters are codes 010-015 and
040.
Dates, which appear after the date keyword, are of the form
Y.mm.dd.hh.mm.ss, where Y is the year, mm the month (01-12), dd the day
(01-31), hh the hour (00-23), mm the minute (00-59), and ss the second
(00-60). Y contains just the last two digits of the year for years
from 1900 through 1999, and all the digits of years thereafter. Dates
use the Gregorian calendar; times use UTC.
The delta nodes form a tree. All nodes whose numbers consist of a sin-
gle pair (e.g., 2.3, 2.1, 1.3, etc.) are on the trunk, and are linked
through the next field in order of decreasing numbers. The head field
in the admin node points to the head of that sequence (i.e., contains
the highest pair). The branch node in the admin node indicates the de-
fault branch (or revision) for most RCS operations. If empty, the de-
fault branch is the highest branch on the trunk.
All delta nodes whose numbers consist of 2n fields (n>=2) (e.g.,
3.1.1.1, 2.1.2.2, etc.) are linked as follows. All nodes whose first
2n-1 number fields are identical are linked through the next field in
order of increasing numbers. For each such sequence, the delta node
whose number is identical to the first 2n-2 number fields of the deltas
on that sequence is called the branchpoint. The branches field of a
node contains a list of the numbers of the first nodes of all sequences
for which it is a branchpoint. This list is ordered in increasing num-
bers.
The following diagram shows an example of an RCS file's organization.
Head
|
|
v / \
--------- / \
/ \ / \ | | / \ / \
/ \ / \ | 2.1 | / \ / \
/ \ / \ | | / \ / \
/1.2.1.3\ /1.3.1.1\ | | /1.2.2.2\ /1.2.2.1.1.1\
--------- --------- --------- --------- -------------
^ ^ | ^ ^
| | | | |
| | v | |
/ \ | --------- / \ |
/ \ | \ 1.3 / / \ |
/ \ ---------\ / / \-----------
/1.2.1.1\ 1.3.1 \ / /1.2.2.1\ 1.2.2.1.1
--------- \ / ---------
^ | ^
| | |
| v |
| --------- |
| \ 1.2 / |
----------------------\ /---------
1.2.1 \ / 1.2.2
\ /
|
|
v
---------
\ 1.1 /
\ /
\ /
\ /
IDENTIFICATION
Author: Walter F. Tichy.
Manual Page Revision: 5.9.4; Release Date: 2019-12-31.
Copyright (C) 2010-2015 Thien-Thi Nguyen.
Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995 Paul Eggert.
Copyright (C) 1982, 1988, 1989 Walter F. Tichy.
SEE ALSO
ci(1), co(1), ident(1), rcs(1), rcsclean(1), rcsdiff(1), rcsmerge(1),
rlog(1).
Walter F. Tichy, RCS--A System for Version Control, Software--Practice
& Experience 15, 7 (July 1985), 637-654.
The full documentation for RCS is maintained as a Texinfo manual. If
the info(1) and RCS programs are properly installed at your site, the
command
info rcs
should give you access to the complete manual. Additionally, the RCS
homepage:
http://www.gnu.org/software/rcs/
has news and links to the latest release, development site, etc.
GNU RCS 5.9.4 2019-12-31 RCSFILE(5)
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