RCSFILE(4)RCSFILE(4)NAMErcsfile - format of RCS file
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
significance 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 doubled;
otherwise, strings may contain arbitrary binary data.
The meta syntax uses the following conventions: `|' (bar) separates
alternatives; `{' and `}' enclose optional phrases; `{' and `}*' enclose
phrases that may be repeated zero or more times; `{' and '}+' enclose
phrases that must appear at least once and may 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 ;}
{ comment {string}; }
{ expand {string}; }
{ newphrase }*
delta ::= num
date num;
author id;
state {id};
branches {num}*;
next {num};
{ newphrase }*
desc ::= desc string
deltatext ::= num
log string
{ newphrase }*
text string
num ::= {digit | .}+
digit ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
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RCSFILE(4)RCSFILE(4)
id ::= {num} idchar {idchar | num}*
sym ::= {digit}* idchar {idchar | digit}*
idchar ::= any visible graphic character except special
special ::= $ | , | . | : | ; | @
string ::= @{any character, with @ doubled}*@
newphrase ::= id word* ;
word ::= id | num | string | :
Identifiers are case sensitive. Keywords are in lower case only. The
sets of keywords and identifiers may overlap. In most environments RCS
uses the ISO 8859/1 encoding: letters are octal codes 101-132, 141-172,
300-326, 330-366 and 370-377, 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 newphrase productions in the grammar are reserved for future
extensions to the format of RCS files. No newphrase will begin with any
keyword already in use.
The delta nodes form a tree. All nodes whose numbers consist of a single
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 default
branch (or revision) for most RCS operations. If empty, the default
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 numbers.
The following diagram shows an example of an RCS file's organization.
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RCSFILE(4)RCSFILE(4)
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\ \ / /1.2.2.1\
--------- \ / ---------
^ | ^
| | |
| v |
| --------- |
| \ 1.2 / |
----------------------\ /---------
\ /
\ /
|
|
v
---------
\ 1.1 /
\ /
\ /
\ /
IDENTIFICATION
Author: Walter F. Tichy, Purdue University, West Lafayette, IN, 47907.
Revision Number: 5.7; Release Date: 1998/01/12.
Copyright c 1982, 1988, 1989 by Walter F. Tichy.
Copyright c 1990, 1991, 1992, 1993, 1994, 1995 by Paul Eggert.
SEE ALSOci(1), co(1), ident(1), rcs(1), rcsdiff(1), rcsmerge(1), rlog(1),
RCSsource(5).
Walter F. Tichy, RCS--A System for Version Control, Software--Practice &
Experience 15, 7 (July 1985), 637-654.
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