RCSFILE (5)
format of RCS file
DESCRIPTION
An \*r 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.
However, white space cannot appear within an id, num, or sym,
and an \*r 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 .
w \w'\f3deltatext\fP '
y \w'\f3newphrase\fP '
\nw<\ny .nr w \ny
x \w'\f3branches\fP'
y \w'{ \f3comment\fP'
\nx<\ny .nr x \ny
y \w'\f3{ branch\fP'
\nx<\ny .nr x \ny
\nwu +\w'::= 'u +\nxu+\w' 'u
#
\f2rcstext ::= \f2admin {\f2delta}* \f2desc {\f2deltatext}*
\f2admin ::= \f3head {\f2num}\f3;
{ \f3branch {\f2num}\f3; }
\f3access {\f2id}*\f3;
\f3symbols {\f2sym \f3: \f2num}*\f3;
\f3locks {\f2id \f3: \f2num}*\f3; {\f3strict ;}
{ \f3comment {\f2string}\f3; }
{ \f3expand {\f2string}\f3; }
{ \f2newphrase }*
\f2delta ::= \f2num
\f3date \f2num\f3;
\f3author \f2id\f3;
\f3state {\f2id}\f3;
\f3branches {\f2num}*\f3;
\f3next {\f2num}\f3;
{ \f2newphrase }*
\f2desc ::= \f3desc \f2string
\f2deltatext ::= \f2num
\f3log \f2string
{ \f2newphrase }*
\f3text \f2string
\f2num ::= {\f2digit | \f3.}+
\f2digit ::= \f30 | \f31 | \f32 | \f33 | \f34 | \f35 | \f36 | \f37 | \f38 | \f39
\f2id ::= {\f2num} \f2idchar {\f2idchar | \f2num}*
\f2sym ::= {\f2digit}* \f2idchar {\f2idchar | \f2digit}*
\f2idchar ::= any visible graphic character except \f2special
\f2special ::= \f3$ | \f3, | \f3. | \f3: | \f3; | \f3@
\f2string ::= \f3@{any character, with \f3@ doubled}*\f3@
\f2newphrase ::= \f2id \f2word* \f3;
\f2word ::= \f2id | \f2num | \f2string | \f3:
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.
Dates, which appear after the
date
keyword, are of the form
\f2Y\f3.\f2mm\f3.\f2dd\f3.\f2hh\f3.\f2mm\f3.\f2ss,
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 (00-60).
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.
The
newphrase
productions in the grammar are reserved for future extensions
to the format of \*r files.
No
newphrase
will begin with any keyword already in use.
The
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
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 \*r operations.
If empty, the default
branch is the highest branch on the trunk.
All
delta
nodes whose numbers consist of
2 n
fields
( n \(>=2)
(e.g., 3.1.1.1, 2.1.2.2, etc.)
are linked as follows.
All nodes whose first
2 n -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
2 n -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 \*r file's organization.
!\np \{\
12
36
1 20
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 /
\ /
\ /
\ /
1
|