NAME
rcsfile — format of RCS files
DESCRIPTION
An RCS file is an ASCII file.
Its contents are described by the grammar below.
The text is free format, that is, spaces, tabs and newline characters
have no significance except in strings.
Strings are enclosed by
@
symbols.
If a string contains the
@
symbol, the symbol must be doubled.
The meta syntax uses the following conventions:
RCS File Grammar
Identifiers are case sensitive.
Keywords are in lowercase only.
The sets of keywords and identifiers may overlap.
<rcstext> ::= <admin> {<delta>}* <desc> {<deltatext>}*
<admin> ::= head {<num>};
access {<id>}*;
symbols {<id> : <num>}*;
locks {<id> : <num>}*; {strict ;}
comment {<string>};
<delta> ::= <num>
date <num>;
author <id>;
state {<id>};
branches {<num>}*;
next {<num>};
<desc> ::= desc <string>
<deltatext> ::= <num>
log <string>
text <string>
<num> ::= {<digit>{.}}+
<digit> ::= 0 | 1 | ... | 9
<id> ::= <letter>{<idchar>}*
<letter> ::= A | B | ... | Z | a | b | ... | z
<idchar> ::= Any printing ASCII character except space,
tab, carriage return, newline, and <special>.
<special> ::= ; | : | , | @
<string> ::= @{any ASCII character, with "@" doubled}*@
RCS File Structure
The
<delta>
nodes form a tree.
All nodes whose numbers consist of a single pair
(for example, 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
(that is, contains the highest pair).
All
<delta>
nodes whose numbers consist of
2n
fields
(n>=2)
(for example, 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
2(n-1)
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.
EXAMPLES
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 /
\ /
\ /
\ /
WARNINGS
RCS is designed to be used with text (ASCII) files only.
Using RCS with nontext (binary) files results in data corruption.
AUTHOR
rcsfile
was developed by
Walter F. Tichy,
Purdue University,
West Lafayette, IN 47907,
USA.
Copyright©
1982 by Walter F. Tichy.
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