rcsfile - format of RCS file
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 can contain arbitrary
binary data.
The meta syntax uses the following conventions: `|' (bar)
separates alternatives; `{' 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 ;}
{ 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
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 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 newphrase productions in the grammar are reserved for
future extensions to the format of RCS files. No new-
phrase 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.
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 /
/
/
/
Author: Walter F. Tichy, Purdue University, West
Lafayette, IN, 47907.
Manual Page Revision: 1.1; Release Date: 1996/08/12.
Copyright (C) 1982, 1988, 1989 Walter F. Tichy.
Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995 Paul
Eggert.
rcsintro(1), 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.
GNU 1996/08/12 3 [ Back ] |
