rcsfile - 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 (collec-
tively, white space) have no significance except in
strings. However, an RCS file must end in a newline char-
acter.
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
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 over-
lap. In most environments RCS uses the ISO 8859/1 encod-
ing: 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 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 con-
sist 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 indi-
cates the default branch (or revision) for most RCS opera-
tions. If empty, the default branch is the highest branch
on the trunk.
All delta nodes whose numbers consist of 2n fields (nP=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 num-
bers. 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 branch-
point. This list is ordered in increasing numbers.
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: 5.1; Release Date: 1991/08/19.
Copyright (C) 1982, 1988, 1989 by Walter F. Tichy.
Copyright (C) 1990, 1991 by Paul Eggert.
SEE ALSO
ci(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.