rcsfile

RCSFILE(5)							   RCSFILE(5)



NAME
       rcsfile - format of RCS file

DESCRIPTION
       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.  However, 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	 dou-
       bled; 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};
		      { newphrase }*

       desc	 ::=  desc	 string

       deltatext ::=  num
		      log	 string
		      { newphrase }*
		      text	 string

       num	 ::=  {digit | .}+

       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 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  (00-60).	  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 RCS 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  RCS  operations.
       If empty, the default branch is the highest branch on the trunk.

       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.

				  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	/
				 \     /
				  \   /
				   \ /



IDENTIFICATION
       Author: Walter F. Tichy, Purdue University, West Lafayette, IN, 47907.
       Manual Page Revision: 5.6; Release Date: 1995/06/05.
       Copyright © 1982, 1988, 1989 Walter F. Tichy.
       Copyright © 1990, 1991, 1992, 1993, 1994, 1995 Paul Eggert.

SEE ALSO
       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.



GNU				  1995/06/05			   RCSFILE(5)