RCSFILE(5)RCSFILE(5)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. 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 {id : 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 | ... | 9
id ::= letter{idchar}*
letter ::= any letter
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.
The newphrase productions in the grammar are reserved for future exten-
sions to the format of RCS files. No newphrase will begin with any key-
word already in use.
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
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 num-
bers.
Example:
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 /
\ /
\ /
\ /
Fig. 1: A revision tree
IDENTIFICATION
Author: Walter F. Tichy, Purdue University, West Lafayette, IN, 47907.
Revision Number: 5.0; Release Date: 1990/08/22.
Copyright (C) 1982, 1988, 1989 by Walter F. Tichy.
Copyright (C) 1990 by Paul Eggert.
SEE ALSOci(1), co(1), ident(1), rcs(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 1990/08/22 3
