rcsfile(4)                                             rcsfile(4)



     NAME
          rcsfile - format of an RCS file

     DESCRIPTION
          An RCS file is an ASCII file.  Its content is  described  by
          the  grammar  below.   The  text  is  free  format; that is,
          spaces, tabs, and newlines have no  significance  except  in
          strings.   Strings  are enclosed by @.  If a string contains
          an @, it must be doubled.

          The metasyntax 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; nonterminal  symbols  are  set  in
          italic font, and literals are set in a constant-width font.

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

          admin       ::=       head     {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, newline, and special.

          special     ::=       ; | : | , | @

          string      ::=       @{any ASCII character, with @ doubled}*@



     April, 1990                                                     1

     rcsfile(4)                                             rcsfile(4)



          Identifiers are case sensitive.  Keywords are  in  lowercase
          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 (2.3, 2.1, 1.3, and so forth) 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  which  contains  the  highest
          pair.

          All delta nodes whose numbers consist  of  2n  fields  (n>2)
          (3.1.1.1, 2.1.2.2, and so forth) 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.

     DISCLAIMER
          This reference manual entry describes a utility  that  Apple
          understands  to have been released into the public domain by
          its author or  authors.   Apple  has  included  this  public
          domain  utility  for  your  convenience.  Use it at your own
          discretion.  Often the source code can be obtained if  addi-
          tional  requirements are met, such as the purchase of a site
          license from an author or institution.

     IDENTIFICATION
          Author: Walter F. Tichy, Purdue University, West  Lafayette,
          IN 47907.
                    c
          Copyright   1982 by Walter F. Tichy.

     SEE ALSO
          ci(1), co(1), ident(1), rcs(1), rcsdiff(1), rcsintro(1),
          rcsmerge(1), rlog(1), sccstorcs(1M).

















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