rcsfile



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
      doubled; 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: 1.3; Release Date: 1996/01/31.
      Copyright c 1982, 1988, 1989 Walter F. Tichy.
      Copyright c 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.