rcsfile.5

早期freebsd实现

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.ds Rv \\$3
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.Id $Id: rcsfile.5,v 5.1 1991/08/19 03:13:55 eggert Exp $
.ds r \s-1RCS\s0
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.TH RCSFILE 5 \*(Dt GNU
.SH NAME
rcsfile \- format of RCS file
.SH DESCRIPTION
An \*r file's
contents are described by the grammar
below.
.PP
The text is free format: space, backspace, tab, newline, vertical
tab, form feed, and carriage return (collectively,
.IR "white space")
have no significance except in strings.
However, an \*r file must end in a newline character.
.PP
Strings are enclosed by
.BR @ .
If a string contains a
.BR @ ,
it must be doubled;
otherwise, strings may contain arbitrary binary data.
.PP
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
.BR boldface ;
nonterminal symbols are in
.IR italics .
.LP
.nr x \w'\f3branches\fP'
.nr y \w'{ \f3comment\fP'
.if \nx<\ny .nr x \ny
.nr y \w'\f3{ branch\fP'
.if \nx<\ny .nr x \ny
.ta \w'\f2deltatext\fP  'u +\w'::=  'u +\nxu+\w'  'u
.fc ~
.nf
\f2rcstext\fP	::=	\f2admin\fP {\f2delta\fP}* \f2desc\fP {\f2deltatext\fP}*
.LP
\f2admin\fP	::=	\f3head\fP	{\f2num\fP}\f3;\fP
		{ \f3branch\fP	{\f2num\fP}\f3;\fP }
		\f3access\fP	{\f2id\fP}*\f3;\fP
		\f3symbols\fP	{\f2id\fP \f3:\fP \f2num\fP}*\f3;\fP
		\f3locks\fP	{\f2id\fP \f3:\fP \f2num\fP}*\f3;\fP  {\f3strict  ;\fP}
		{ \f3comment\fP	{\f2string\fP}\f3;\fP }
		{ \f3expand\fP	{\f2string\fP}\f3;\fP }
		{ \f2newphrase\fP }*
.LP
\f2delta\fP	::=	\f2num\fP
		\f3date\fP	\f2num\fP\f3;\fP
		\f3author\fP	\f2id\fP\f3;\fP
		\f3state\fP	{\f2id\fP}\f3;\fP
		\f3branches\fP	{\f2num\fP}*\f3;\fP
		\f3next\fP	{\f2num\fP}\f3;\fP
		{ \f2newphrase\fP }*
.LP
\f2desc\fP	::=	\f3desc\fP	\f2string\fP
.LP
\f2deltatext\fP	::=	\f2num\fP
		\f3log\fP	\f2string\fP
		{ \f2newphrase\fP }*
		\f3text\fP	\f2string\fP
.LP
\f2num\fP	::=	{\f2digit\fP{\f3.\fP}}+
.LP
\f2digit\fP	::=	\f30\fP | \f31\fP | .\|.\|. | \f39\fP
.LP
\f2id\fP	::=	\f2letter\fP{\f2idchar\fP}*
.LP
\f2letter\fP	::=	any letter
.LP
\f2idchar\fP	::=	any visible graphic character except \f2special\fP
.LP
\f2special\fP	::=	\f3$\fP | \f3,\fP | \f3.\fP | \f3:\fP | \f3;\fP | \f3@\fP
.LP
\f2string\fP	::=	\f3@\fP{any character, with \f3@\fP doubled}*\f3@\fP
.LP
\f2newphrase\fP	::=	\f2id\fP \f2word\fP* \f3;\fP
.LP
\f2word\fP	::=	\f2id\fP | \f2num\fP | \f2string\fP | \f3:\fP
.fi
.PP
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.
.PP
The
.I newphrase
productions in the grammar are reserved for future extensions
to the format of \*r files.
No
.I newphrase
will begin with any keyword already in use.
.PP
The
.I 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
.B next
field in order of decreasing numbers.
The
.B head
field in the
.I admin
node points to the head of that sequence (i.e., contains
the highest pair).
The
.B branch
node in the admin node indicates the default
branch (or revision) for most \*r operations.
If empty, the default
branch is the highest branch on the trunk.
.PP
All
.I delta
nodes whose numbers consist of
.RI 2 n
fields
.RI ( n \(\fP=2)
(e.g., 3.1.1.1, 2.1.2.2, etc.)
are linked as follows.
All nodes whose first
.RI 2 n \-1
number fields are identical are linked through the
.B next
field in order of increasing numbers.
For each such sequence,
the
.I delta
node whose number is identical to the first
.RI 2 n \-2
number fields of the deltas on that sequence is called the branchpoint.
The
.B 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.
.LP
.nf
.vs 12
.ne 38
Example:
.if t .in +0.5i
.cs 1 20
.eo

                           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  /
                          \     /
                           \   /
                            \ /

.ec
.if t .in
.cs 1
.ce
Fig. 1: A revision tree
.vs
.fi
.PP
.SH IDENTIFICATION
.de VL
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Author: Walter F. Tichy,
Purdue University, West Lafayette, IN, 47907.
.br
Revision Number: \*(Rv; Release Date: \*(Dt.
.br
Copyright \(co 1982, 1988, 1989 by Walter F. Tichy.
.br
Copyright \(co 1990, 1991 by Paul Eggert.
.SH SEE ALSO
ci(1), co(1), ident(1), rcs(1), rcsdiff(1), rcsmerge(1), rlog(1),
.br
Walter F. Tichy,
\*r\*-A System for Version Control,
.I "Software\*-Practice & Experience"
.BR 15 ,
7 (July 1985), 637-654.