RCSFILE(5) UNIX Programmer's Manual RCSFILE(5)
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. How-
ever, 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};
{ commitid id; }
{ newphrase }*
desc ::= desc string
deltatext ::= num
log string
{ newphrase }*
text string
num ::= {digit | .}+
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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 digit or 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 (00-59). If Y contains exactly
two digits, they are the last two digits of a year from 1900
through 1999; otherwise, Y contains all the digits of the
year. Dates use the Gregorian calendar. Times use UTC,
except that for portability's sake leap seconds are not
allowed; implementations that support leap seconds should
output 59 for ss during an inserted leap second, and should
accept 59 for a deleted leap second.
The commitid is followed by an id token. This token is
intended to be unique across multiple files and is used to
help group files as being a part of the same logical commit.
This token must uniquely identify the commit operation that
was applied to a set of RCS files. In particular, it must be
unique among all the commitids in this file.
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 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 points to the head of
that sequence (i.e., contains the highest pair). The branch
field indicates the default branch (or revision) for most
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RCS operations. If empty, the default branch is the highest
branch on the trunk. The symbols field associates symbolic
names with revisions. For example, if the file contains sym-
bols rr:1.1; then rr is a name for revision 1.1.
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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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: 5.6; Release Date: 1995/06/05.
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.
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