RCSFILE(5L)	    UNIX Programmer's Manual	      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>.




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RCSFILE(5L)	    UNIX Programmer's Manual	      RCSFILE(5L)



     <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 con-
     sist 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 bran-
     chpoint.  This list is ordered in increasing numbers.



























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RCSFILE(5L)	    UNIX Programmer's Manual	      RCSFILE(5L)



     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 _P_r_o_c_e_e_d_i_n_g_s _o_f _t_h_e _6_t_h _I_n_t_e_r_-
     _n_a_t_i_o_n_a_l _C_o_n_f_e_r_e_n_c_e _o_n _S_o_f_t_w_a_r_e _E_n_g_i_n_e_e_r_i_n_g, IEEE, Tokyo,
     Sept. 1982.



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