RCSFILE(5RCS)           COMMAND REFERENCE           RCSFILE(5RCS)



NAME
     rcsfile - format of RCS file

DESCRIPTION
     An RCS file is an ASCII file. Its contents is 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 optinal 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>};
                           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}*@




Printed 5/12/88                                                 1

RCSFILE(5RCS)           COMMAND REFERENCE           RCSFILE(5RCS)



     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).

     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:
     Maximum Number of Revisions

     When an RCS file contains 700 or more revisions, all RCS
     commands except for ident and rlog -c will print a warning
     message (if possible) saying that the maximum number of
     revisions is about to be reached. When the file contains 719
     revisions, no further checkins are allowed. This maximum
     applies to the total number of revisions in all branches.
     Starting a new branch will not release any space.

     There are two things that can be done when this happens.
     The first is to delete some of the revisions using the -o
     flag of the rcs command.  This should be done with some
     care, making sure that significant modifications are kept
     separate.

     The other method of fixing this problem is to make a copy of
     the RCS file and delete all of the old revisions in the
     original file. For example, if the RCS file prog.c,v has 715
     revisions (1.1 through 1.716), the following commands will
     save the first 700 revisions in another file, and leave the
     last 15 revisions where they can be easily found.

          cp prog.c,v prog.old,v
          rcs -o1.701-1.716 prog.old
          rcs -o1.1-1.700 prog.c

     Revision 1.348 can be retrieved by the command co -r 1.348
     prog.old.  Revisions after 1.700 can be checked out of
     prog.c,v.  Note that the rcs command may take a while to
     delete 700 revisions.



Printed 5/12/88                                                 2

RCSFILE(5RCS)           COMMAND REFERENCE           RCSFILE(5RCS)



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




















































Printed 5/12/88                                                 3

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