RCSFILE(5L)															       RCSFILE(5L)

NAME

       rcsfile - format of RCS file

DESCRIPTION

       An  RCS	file  is an ASCII file. Its contents are described by the grammar below. The text is free format, i.e., spaces, tabs and new lines
       have no significance except in strings. Strings are enclosed by `@'.  If a string contains a `@', it must be doubled.

       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;
       `<' and `>' enclose nonterminals.

       <rcstext>      ::=  <admin> {<delta>}* <desc> {<deltatext>}*

       <admin>	      ::=  head      {<num>};
			   branch    {<num>};
			   access    {<id>}*;
			   symbols   {<id> : <num>}*;
			   locks     {<id> : <num>}*;
			   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, new line, and <special>.

       <special>      ::=  ; | : | , | @

       <string>       ::=  @{any ASCII character, with `@' doubled}*@

       Identifiers are case sensitive. Keywords are in lower case only.  The sets of keywords and identifiers may overlap.

       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 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.

       Example:
				  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	/
				      /
				     /
				    /

								 Fig. 1: A revision tree

IDENTIFICATION

       Author: Walter F. Tichy, Purdue University, West Lafayette, IN, 47907.
       Revision Number: 1.1 ; Release Date: 87/03/11 .
       Copyright (C) 1982 by Walter F. Tichy.

SEE ALSO

       ci(1L), co(1L), ident(1L), rcs(1L), rcsdiff(1L), rcsmerge(1L), rlog(1L),
       Walter  F. Tichy, "Design, Implementation, and Evaluation of a Revision Control System," in Proceedings of the 6th International Conference
       on Software Engineering, IEEE, Tokyo, Sept. 1982.

Purdue University														       RCSFILE(5L)