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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, white space cannot appear within an id, num, or sym,
and an \*r file must end with a newline.
PP
Strings are enclosed by
BR @ .
If a string contains a
BR @ ,
it must be doubled;
otherwise, strings can contain arbitrary binary data.
PP
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
BR boldface ;
nonterminal symbols are in
IR italics .
LP
nr w \w'\f3deltatext\fP '
nr y \w'\f3newphrase\fP '
if \nw<\ny .nr w \ny
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 \nwu +\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 {\f2sym\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 | \f32\fP | \f33\fP | \f34\fP | \f35\fP | \f36\fP | \f37\fP | \f38\fP | \f39\fP
LP
\f2id\fP ::= {\f2num\fP} \f2idchar\fP {\f2idchar\fP | \f2num\fP}*
LP
\f2sym\fP ::= {\f2digit\fP}* \f2idchar\fP {\f2idchar\fP | \f2digit\fP}*
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 can overlap.
In most environments \*r uses the \s-1ISO\s0 8859/1 encoding:
visible graphic characters are codes 041\-176 and 240\-377,
and white space characters are codes 010\-015 and 040.
PP
Dates, which appear after the
B date
keyword, are of the form
\f2Y\fP\f3.\fP\f2mm\fP\f3.\fP\f2dd\fP\f3.\fP\f2hh\fP\f3.\fP\f2mm\fP\f3.\fP\f2ss\fP,
where
I Y
is the year,
I mm
the month (01\-12),
I dd
the day (01\-31),
I hh
the hour (00\-23),
I mm
the minute (00\-59),
and
I ss
the second (00\-60).
I 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.
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 \*[Ge]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
The following diagram shows an example of an \*r file's organization.
if !\np \{\
nf
vs 12
ne 36
cs 1 20
eo
