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This manual is for GNU RCS (version 5.9.4, 18 January 2015).

   Copyright (C) 2010-2015 Thien-Thi Nguyen

     Permission is granted to copy, distribute and/or modify this
     document under the terms of the GNU Free Documentation License,
     Version 1.3 or any later version published by the Free Software
     Foundation; with no Invariant Sections, with no Front-Cover Texts,
     and with no Back-Cover Texts.  A copy of the license is included in
     the appendix entitled "GNU Free Documentation License".

* Menu:

* Overview::            General purpose and information.
* Usage::               How to use RCS.
* Hacking::             With source, you can help improve things.
* GNU FDL::             Copying and sharing this documentation.
* Index::

-- The Detailed Node Listing --

* Credits::             Who did what, and when.
* Concepts::            What is a revision?  How can RCS help?
* Quick tour::          A hands-on introduction to using RCS.

* Common elements::
* ci::
* co::
* ident::
* merge::
* rcs::
* rcsclean::
* rcsdiff::
* rcsmerge::
* rlog::

Common elements
* Revision options::
* Date option::
* Description option::
* Substitution mode option::
* Misc common options::
* Environment::

* File format::
* Still missing::
* Reporting bugs::

File: rcs.info,  Node: Overview,  Next: Usage,  Prev: Top,  Up: Top

1 Overview

GNU RCS (Revision Control System) manages multiple revisions of files.
RCS can store, retrieve, log, identify, and merge revisions.  It is
useful for files that are revised frequently, e.g.  programs,
documentation, graphics, and papers.  It can handle text as well as
binary files, although functionality is reduced for the latter.

   A normal installation includes the commands: ci, co, ident, merge,
rcs, rcsclean, rcsdiff, rcsmerge and rlog (*note Usage::).  These are
small and fast programs (amenable to scripting) and indeed the
distribution also includes the script rcsfreeze showing some of the

   RCS works with versions stored on a single filesystem or machine,
edited by one person at a time.  Other version control systems, such as
Bazaar (<http:///www.gnu.org/software/bazaar>), CVS, Subversion, and
Git, support distributed access in various ways.  Which is more
appropriate depends on the task at hand.

* Menu:

* Credits::             Who did what, and when.
* Concepts::            What is a revision?  How can RCS help?
* Quick tour::          A hands-on introduction to using RCS.

File: rcs.info,  Node: Credits,  Next: Concepts,  Up: Overview

1.1 Credits

RCS was designed and built by Walter F. Tichy of Purdue University.  RCS
version 3 was released in 1983.

   Adam Hammer, Thomas Narten, and Daniel Trinkle of Purdue supported
RCS through version 4.3, released in 1990.  Guy Harris of Sun
contributed many porting fixes.  Paul Eggert of System Development
Corporation contributed bug fixes and tuneups.  Jay Lepreau contributed
4.3BSD support.

   Paul Eggert of Twin Sun wrote the changes for RCS versions 5.5 and
5.6 (1991).  Rich Braun of Kronos and Andy Glew of Intel contributed
ideas for new options.  Bill Hahn of Stratus contributed ideas for
setuid support.  Ideas for piece tables came from Joe Berkovitz of
Stratus and Walter F. Tichy.  Matt Cross of Stratus contributed test
case ideas.  Adam Hammer of Purdue QAed.

   Paul Eggert wrote most of the changes for RCS 5.7.  K. Richard Pixley
of Cygnus Support contributed several bug fixes.  Robert Lupton of
Princeton and Daniel Trinkle contributed ideas for '$Name' expansion.
Brendan Kehoe of Cygnus Support suggested rlog's '-N' option.  Paul
D. Smith of Data General suggested improvements in option and error
processing.  Adam Hammer of Purdue QAed.

   Thien-Thi Nguyen is responsibile for RCS 5.8.  He modernized the code
base, build system, and manual pages, fixing some bugs on the way.  He
added standard '--help', '--version' processing, and wrote the
documentation you are reading (gladly taking inspiration from the
paper(1) and manpages originally written by Walter F. Tichy).

   ---------- Footnotes ----------

   (1) Source (troff) and several output formats are available from the
RCS homepage (http://www.gnu.org/software/rcs/).

File: rcs.info,  Node: Concepts,  Next: Quick tour,  Prev: Credits,  Up: Overview

1.2 Concepts

1.2.1 Interaction model

The interaction model is straightforward.  For each working file, you
initialize its RCS file once, then enter a cycle of checkout,
modification, and checkin operations.  Along the way, you can tweak some
of the RCS file's metadata, as well.  All of this is done through RCS
commands; you need not modify the RCS file directly (and in fact you
should probably avoid doing so lest RCS become confused).  This model is
somewhat analogous to using a library (of books).  With a library, you
sign up for a library card (initialize), then enter a cycle of taking a
book home (checkout), enjoying it (NB: *without* modification, one
hopes), and returning it to the library (checkin).

   Furthermore, you can compare revisions in the RCS file against each
other, examine the user- (hopefully high) quality descriptions of the
changes each revision embodies, merge selected revisions, and so forth.

1.2.2 Working file

RCS commands operate on one pair of files at a time.  The "working file"
is what you normally view and edit (e.g., a file of C programming
language source code named 'a.c').  Because the working file's contents
can be extracted from the RCS file (called "instantiating a working
file"), it can be safely deleted to regain some disk space.

1.2.3 RCS file

The "RCS file" is a separate file, conventionally placed in the
subdirectory 'RCS', wherein RCS commands organize the initial and
subsequent "revisions" of the working file, associating with each
revision a unique revision number along with the remembered particulars
of the checkin that produced it.  It also contains a "description" of
the working file and various other metadata, described below.

   The RCS file is also known (colloquially) as the "comma-v file", due
to its name often ending in ',v' (e.g., 'a.c,v').

   A "revision number" is a branch number followed by a dot followed by
an integer, and a "branch number" is an odd number of integers separated
by dot.  A revision number with one dot (implying a branch number
without any dots) is said to be "on the trunk".  All integers are
positive.  For example:

     1.1         -- revision number for initial checkin (typically);
                    branch number: 1    -- more complicated (perhaps after much gnarly hacking);
                    branch number: 9.4.1

     333.333.333 -- not a valid revision number;
                    however, a perfectly valid branch number

The "branch point" of a non-trunk branch is the revision number formed
by removing the branch's trailing integer.  To compute the "next higher"
branch or revision number, add one to the trailing integer.  The
highest-numbered revision on a branch is called the "tip" of the branch
(or "branch tip").  Continuing the example:

     1.1         -- on trunk; no branch point;
                    next higher branch number:   2
                    next higher revision number: 1.2    -- not on trunk; branch point:  9.4
                    next higher branch number:   9.4.2
                    next higher revision number:

     333.333.333 -- not on trunk; branch point:  333.333
                    next higher branch number:   333.333.334
                    next higher revision number: 333.333.333.1

In addition to this "tree" of thus-linked revisions, the RCS file keeps
track of the "default branch", i.e., the branch whose tip corresponds to
the most recent checkin; as well as the "symbolic names", a list of
associations between a user-supplied (and presumably meaningful) symbol
and an underlying branch or revision number.

   The RCS file contains two pieces of information used to implement its
"access control policy".  The first is a list of usernames.  If
non-empty, only those users listed can modify the RCS file (via RCS
commands).  The second is a list of "locks", i.e., association between a
username and a revision number.  If a lock 'USERNAME:REVNO' exists, that
means only USERNAME may modify REVNO (that is, do a checkin operation to
deposit the next higher revision, or a higher revision number on the
same branch as REVNO).

1.2.4 Fundamental operations

The "checkin" operation records the contents of the working file in the
RCS file, assigning it a new (normally the next higher) revision number
and recording the username, timestamp, "state" (a short symbol), and
user-supplied "log message" (a textual description of the changes
leading to that revision).  It uses diff to find the differences between
the tip of the default branch and the working file, thereby writing the
minimal amount of information needed to be able to recreate the contents
of the previous tip.

   The "checkout" operation identifies a specific revision from the RCS
file and either displays the content to standard output or instantiates
a working file, overwriting any current instantiation with the selected
revision.  In either case, the content may undergo "keyword expansion",
which replaces text of the form '$Keyword$' with (possibly) different
text comprising the keyword and its "value", depending on the current
keyword expansion mode (*note Substitution mode option::).

1.2.5 Keywords

The keywords and their values are:

     The login name of the user who checked in the revision.

     The date and time the revision was checked in.  May include an
     appended timezone offset.

     A standard header containing the absolute RCS filename, the
     revision number, the date and time, the author, the state, and the
     locker (if locked).  May include an appended timezone offset.

     Same as 'Header', except that only the basename appears (no
     directory components).

     The login name of the user who locked the revision (empty if not

     The log message supplied during checkin, preceded by a header
     containing the RCS filename, the revision number, the author, and
     the date and time.  May include an appended timezone offset.

     Existing log messages are not replaced.  Instead, the new log
     message is inserted after '$Log:...$'.  This is useful for
     accumulating a complete change log in a source file.

     Each inserted line is prefixed by the string that prefixes the
     '$Log$' line.  For example, if the '$Log$' line is

          // $Log: tan.cc $

     then RCS prefixes each line of the log with '// ' (slash, slash,
     space).  This is useful for languages with comments that go to the
     end of the line.

     The convention for other languages is to use a ' * ' (space,
     asterisk, space) prefix inside a multiline comment.  For example,
     the initial log comment of a C program conventionally is of the
     following form:

            * $Log$

     For backwards compatibility with older versions of RCS, if the log
     prefix is '/*' or '(*' surrounded by optional white space, inserted
     log lines contain a space instead of '/' or '('; however, this
     usage is obsolescent and should not be relied on.

     The symbolic name used to check out the revision, if any.  For
     example, 'co -rJoe' generates '$Name: Joe $'.  Plain co generates
     just '$Name: $'.

     The basename of the RCS file.

     The revision number assigned to the revision.

     The absolute RCS filename.

     The state assigned to the revision with the '-s' option of rcs or

File: rcs.info,  Node: Quick tour,  Prev: Concepts,  Up: Overview

1.3 Quick tour

This section complements the preceding section (*note Concepts::),
presenting a handful of RCS commands in quick succession.  For details
on individual RCS commands, *Note Usage::.

   Suppose you have a file 'f.c' that you wish to put under control of
RCS. If you have not already done so, make an 'RCS' directory with the

     mkdir RCS

Then invoke the checkin command:

     ci f.c

This command creates an RCS file in directory 'RCS', stores 'f.c' into
it as revision 1.1, and deletes 'f.c'.  It also asks you for a
description.  The description should be a synopsis of the contents of
the file.  All later checkin commands will ask you for a log entry,
which should summarize the changes that you made.

   To get back the working file 'f.c' in the previous example, use the
checkout command:

     co f.c

This command extracts the latest revision from the RCS file and writes
it into 'f.c'.  If you want to edit 'f.c', you must lock it as you check
it out, with the command:

     co -l f.c

You can now edit 'f.c'.  Suppose after some editing you want to know
what changes that you have made.  The command:

     rcsdiff f.c

tells you the difference between the most recently checked-in version
and the working file.  You can check the file back in by invoking:

     ci f.c

This increments the revision number properly.  If ci complains with the

     ci error: no lock set by your name

then you have tried to check in a file even though you did not lock it
when you checked it out.  Of course, it is too late now to do the
checkout with locking, because another checkout would overwrite your
modifications.  Instead, invoke:

     rcs -l f.c

This command will lock the latest revision for you, unless somebody else
got ahead of you already.  In this case, you'll have to negotiate with
that person.

   Locking assures that you, and only you, can check in the next update,
and avoids nasty problems if several people work on the same file.  Even
if a revision is locked, it can still be checked out for reading,
compiling, etc.  All that locking prevents is a checkin by anybody but
the locker.

   If your RCS file is private, i.e., if you are the only person who is
going to deposit revisions into it, strict locking is not needed and you
can turn it off.  If strict locking is turned off, the owner of the RCS
file need not have a lock for checkin; all others still do.  Turning
strict locking off and on is done with the commands:

     rcs -U f.c    # disable strict locking
     rcs -L f.c    # enable strict locking

   If you don't want to clutter your working directory with RCS files,
create a subdirectory called 'RCS' in your working directory, and move
all your RCS files there.  RCS commands will look first into that
directory to find needed files.  All the commands discussed above will
still work, without any modification.  *Note Common elements::.

   To avoid the deletion of the working file during checkin (in case you
want to continue editing or compiling), invoke one of:

     ci -l f.c     # checkin + locked checkout
     ci -u f.c     # checkin + unlocked checkout

These commands check in 'f.c' as usual, then perform an implicit
checkout.  The first form also locks the checked in revision, the second
one doesn't.  Thus, these options save you one checkout operation.  The
first form is useful if you want to continue editing, the second one if
you just want to read the file.  Both update the keyword substitutions
in your working file *note Concepts::.

   You can give ci the number you want assigned to a checked-in
revision.  Assume all your revisions were numbered 1.1, 1.2, 1.3, etc.,
and you would like to start release 2.  Either of the commands:

     ci -r2 f.c
     ci -r2.1 f.c

assigns the number 2.1 to the new revision.  From then on, ci will
number the subsequent revisions with 2.2, 2.3, etc.  The corresponding
co commands:

     co -r2 f.c
     co -r2.1 f.c

retrieve the latest revision numbered 2.x and the revision 2.1,
respectively.  co without a revision number selects the latest revision
on the trunk, i.e.  the highest revision with a number consisting of two
fields.  Numbers with more than two fields are needed for branches.  For
example, to start a branch at revision 1.3, invoke:

     ci -r1.3.1 f.c

This command starts a branch numbered 1 at revision 1.3, and assigns the
number to the new revision.  Here is a diagram showing the new
revision in relation to its branch and the trunk.

     1.1  --  1.2  --  1.3  --  1.4  --  1.5
                     [1.3.1]  --

For more information about branches, *Note Concepts::.

File: rcs.info,  Node: Usage,  Next: Hacking,  Prev: Overview,  Up: Top

2 Usage

This chapter describes how to invoke RCS commands, including common
command-line elements, as well options specific to each command.

* Menu:

* Common elements::
* ci::
* co::
* ident::
* merge::
* rcs::
* rcsclean::
* rcsdiff::
* rcsmerge::
* rlog::

File: rcs.info,  Node: Common elements,  Next: ci,  Up: Usage

2.1 Common elements

All RCS commands accept '--help' and '--version'.  *Note
(standards)Command-Line Interfaces::.

   Aside from '--help' and '--version', RCS commands take the form
'-LETTER[ARG]', i.e., a hyphen followed by a single letter, optionally
followed by extra information.  The square braces mean that the extra
information is optional.  (No square braces means that the extra
information is required.)  In any case, when specified, the extra
information *must* abut the letter; there can be no intervening

     co -u 1.4 foo   # wrong, space between -u and 1.4
     co -u1.4  foo   # ok

Furthermore, options must appear before file names (if any) on the
command line.

     ident foo -q    # wrong, option after file name
     ident -q foo    # ok

Lastly, pairs of RCS and working files can be specified in three ways:
(a) both are given, (b) only the working file is given, (c) only the RCS
file is given.  For (a), both RCS and working files may have arbitrary
directory components; RCS commands pair them up intelligently.  For (b),
RCS commands will look first into the directory './RCS', if it exists,
to find the associated RCS file.

* Menu:

* Revision options::
* Date option::
* Description option::
* Substitution mode option::
* Log message option::
* Misc common options::
* Environment::

File: rcs.info,  Node: Revision options,  Next: Date option,  Up: Common elements

2.1.1 Revision options

As to be expected in a revision control system, many options are of the
form '-FLAG[REV]', where FLAG is a single letter (e.g., 'r').  If
ommitted, REV defaults to the latest revision on the default branch.  A
revision can be specified in many ways:

     Straightforward dot-notation, where BR specifies the branch.

     Like BR.N, using the default branch.

     Like BR.N, using the a command-specific computation of N, given the
     current tip I.  For ci (*note ci::), N would be 'I + 1', while for
     other commands N would be simply I.

     This is the symbolic name of a revision, as assigned previously by
     a 'ci -n' or 'ci -N' command.

     The command computes the effective revision by examining the values
     of keyword expansions in the working file.

For commands that accept a range of revisions, the syntax is generally
'REV1:REV2', i.e., two revisions (specified as described above)
separated by a colon.

File: rcs.info,  Node: Date option,  Next: Description option,  Prev: Revision options,  Up: Common elements

2.1.2 Date option

Some commands accept an option of the form '-dDATE' to specify a "date",
an absolute point in time (to second resolution), expressed in a "date
format".  These also accept '-zZONE' to specify the timezone.  The
special value 'LT' stands for the "local time zone".  RCS recognizes
many date formats and time zones.  For example, the following dates are
equivalent if local time is January 11, 1990, 8pm Pacific Standard Time,
eight hours west of Coordinated Universal Time (UTC):

     8:00 pm lt
     4:00 AM, Jan. 12, 1990           default is UTC
     1990-01-12 04:00:00+00           ISO 8601 (UTC)
     1990-01-11 20:00:00-08           ISO 8601 (local time)
     1990/01/12 04:00:00              traditional RCS format
     Thu Jan 11 20:00:00 1990 LT      output of ctime(3) + LT
     Thu Jan 11 20:00:00 PST 1990     output of date(1)
     Fri Jan 12 04:00:00 GMT 1990
     Thu, 11 Jan 1990 20:00:00 -0800  Internet RFC 822
     12-January-1990, 04:00 WET

Most fields in the date and time can be defaulted.  The default time
zone is normally UTC, but this can be overridden by the '-z' option.
The other defaults are determined in the order year, month, day, hour,
minute, and second (most to least significant).  At least one of these
fields must be provided.  For omitted fields that are of higher
significance than the highest provided field, the time zone's current
values are assumed.  For all other omitted fields, the lowest possible
values are assumed.  For example, without '-z', the date '20, 10:30'
defaults to '10:30:00 UTC' of the 20th of the UTC time zone's current
month and year.  Note that for the shell, the date/time must be quoted
if it contains spaces.

   RCS also accepts some other formats which specify only the date
portion (omitting the time portion):

     DDD is the day of year, 1-366.

     WW is the ISO week number, 0-53 (actually, ISO week numbers are
     1-53; week 0 is a GNU RCS extension); and D is the ISO day number,
     1-7 (Monday through Sunday).

File: rcs.info,  Node: Description option,  Next: Substitution mode option,  Prev: Date option,  Up: Common elements

2.1.3 Description option

Some commands accept an option of the form '-t-TEXT' or '-tFILE-NAME'.
This option is to set or update the RCS file description text.  In the
first form, TEXT is used directly, excluding the leading hyphen ('-')
that distinguishes the two forms.  In the second form, the description
text is taken from the contents of FILE-NAME.

File: rcs.info,  Node: Substitution mode option,  Next: Log message option,  Prev: Description option,  Up: Common elements

2.1.4 Substitution mode option

Some commands accept an option of the form '-kSUBST', used to control
how keywords (*note Concepts::) are expanded in the working file.  In
the following table of SUBST values, the example keyword is 'Revision'
and its value is '5.13'.

     Generate '$Revision: 5.13 $' (dollar-sign, keyword, colon, space,
     value, space, dollar-sign).  A locker's name is inserted in the
     value of the 'Header', 'Id' and 'Locker' keyword strings only as a
     file is being locked, i.e., by 'ci -l' and 'co -l'.  This is the
     default substitution mode.

     Like '-kkv', except that a locker's name is always inserted if the
     given revision is currently locked.

     Generate '$Revision$' (dollar-sign, keyword, dollar-sign).  This is
     useful when comparing different revisions of a file.  Log messages
     are inserted after 'Log' keywords even if '-kk' is specified, since
     this tends to be more useful when merging changes.

     Like '-kkv', but use the old value present in the working file just
     before it was checked in.  This can be useful for file formats that
     cannot tolerate any changes to substrings that happen to take the
     form of keyword strings.

     Like '-ko', but do all file i/o in binary mode.  This makes little
     difference on POSIX and Unix hosts, but on DOS-like hosts one
     should use 'rcs -i -kb' to initialize an RCS file intended to be
     used for binary files.  Also, on all hosts, rcsmerge normally
     refuses to merge files when '-kb' is in effect.

     Generate '5.13' (value only).  Further keyword substitution cannot
     be performed once the keyword names are removed, so this should be
     used with care.  Because of this danger of losing keywords, '-kv'
     cannot be combined with '-l', and the owner write permission of the
     working file is turned off; to edit the file later, check it out
     again without '-kv'.

File: rcs.info,  Node: Log message option,  Next: Misc common options,  Prev: Substitution mode option,  Up: Common elements

2.1.5 Log message option

Both 'ci' and 'rcs' allow a log message to be specified with the '-m'
option.  If the MSG argument to this option is empty, RCS uses the
default '*** empty log message ***'.  This particular message is handled
specially (i.e., filtered out) by 'rlog'.

File: rcs.info,  Node: Misc common options,  Next: Environment,  Prev: Log message option,  Up: Common elements

2.1.6 Misc common options

Other common options are '-I', '-q', '-s', '-T', '-V', '-w', '-x'.

     This option enables "interactive mode".  More precisely, it
     *forces* interactive mode, whereby RCS commands believe that their
     standard input is a terminal, normally a precondition for
     displaying a prompt to receive input (such as a log message on
     checkin).  The intention of '-I' is for scripting situations where
     standard input is actually not a terminal but you know beforehand
     (without prompting) that input is needed and you are ready to
     provide it on standard input anyway.

     This option enables "quiet mode".  Commands work silently (unless
     there is an error condition), and suppress warnings and prompts.

     Specify the state to be STATE.

     This option controls how commands timestamp the RCS file.
     Normally, RCS commands set the RCS file's timestamp when modifying
     it in the "natural" way (without taking any particular care).  With
     '-T', on the other hand, the commands either preserve the timestamp
     (for standalone lock/unlock operations), or use the timestamp of
     the working file (for ci).

     This can be useful if the RCS file is found in a makefile target's
     list of prerequisites (*note (make)Rule Syntax::), that is, if some
     target should be rebuilt if the RCS file is newer than it.  In that
     case, you can do 'rcs -u -T', for example, to unlock a revision in
     the RCS file without triggering a recompilation.

     Behave like '--version', i.e., display command version information
     and exit successfully.  *NB*: This option is obsolete and its
     *support will be removed* in some future release.

     N specifies the RCS (major) version to emulate.  Valid values for N
     are: 3, 4, 5.  Version 5 is the current version, so '-V5' does
     nothing special.

     In versions prior to 5, RCS outputs '\t' (tab, U+09) between the
     ':' (colon) and the value (for keyword substitution) instead of
     space, uses the RCS file 'comment' string to prefix each line in
     the 'Log' expansion instead of computing it on the fly from the
     input text, writes/reads localtime instead of UTC, and displays
     slightly different output for rlog.

     For version 4, the 'Header' expansion unconditionally includes
     'Locker: LOCKER', as if the 'kvl' substitution mode were specified
     (*note Substitution mode option::).

     For version 3, the 'Header' expansion omits the directories from
     the filename and says only 'Locked' instead of the state.

     Some commands accept an option of the form '-wLOGIN' to specify the
     login name of the author of a revision, i.e., "who" is responsible.

     Specify SUFF as the slash-separated list of file name suffixes used
     to recognize an RCS file.  The default value is ',v/', that is,
     first try with ',v' then try with an empty suffix.

     This "basename search" occurs within (i.e., starting from the
     beginning) the larger "directory search" loop, which comprises two
     candidates: 'd/RCS' and 'd', where D is the directory component of
     the working file name.  For example, given the working file 'a.c'
     in the current directory, RCS tries, in order, these candidates:


     Note that the last candidate is impossible (and is in fact
     discarded), because the working and RCS files cannot have the same

File: rcs.info,  Node: Environment,  Prev: Misc common options,  Up: Common elements

2.1.7 Environment

Various environment variables influence how RCS works.

 -- Environment Variable: RCSINIT
     Another way to set common options is with the 'RCSINIT' environment
     variable.  This is a space-separated list of options.  Use '\'
     (backslash) to escape significant space.  For example:

          # Set the value; make it available to subsequent commands.
          RCSINIT="-q -x/,v -zLT"
          export RCSINIT

          # Use it (implicitly).
          rlog -L foo

     This example, in Bourne shell syntax, arranges for RCS commands to
     operate as if each command-line had prepended '-q -x/,v -zLT' to
     the rest of the command-line.  The effective command-line that rlog
     sees is thus '-q -x/,v -zLT -L foo'.

 -- Environment Variable: RCS_MEM_LIMIT
     Normally, for speed, commands either memory map or copy into memory
     the RCS file if its size is less than the "memory limit", currently
     defaulting to "unlimited".  Otherwise (or if the initially-tried
     speedy ways fail), the commands fall back to using standard i/o

     You can adjust the memory limit by setting the 'RCS_MEM_LIMIT'
     environment variable to a numeric value (measured in kilobytes).
     An empty value is silently ignored.

     As a side effect, specifying the memory limit inhibits fall-back to
     slower routines.  (This env var is mostly intended for testing RCS;
     normally, you can leave it unset.  Probably it will be removed in a
     future release.)

 -- Environment Variable: TMPDIR
 -- Environment Variable: TMP
 -- Environment Variable: TEMP
     Commands sometimes create temporary files, normally in a
     system-dependent directory, such as '/tmp'.  You can override this
     directory by specifying another one as the value of one of the
     environment variables 'TMPDIR', 'TMP', or 'TEMP' (checked in that

 -- Environment Variable: LOGNAME
 -- Environment Variable: USER
     Absent '-wLOGIN', or when LOGIN is omitted (*note Misc common
     options::), commands check environment variables 'LOGNAME' and
     'USER' (in that order).  If neither of these are set, RCS queries
     the host for, and uses, your login.

File: rcs.info,  Node: ci,  Next: co,  Prev: Common elements,  Up: Usage

2.2 Invoking ci

     rcs ci [options] file ...
     (or "ci" instead of "rcs ci")

The ci command adds a revision to the RCS file reflecting the current
state of the working file.  This operation is also known as "checkin".

     Force new entry, even if no content changed.

     *Note Misc common options::.

     Initial checkin; error if the RCS file already exists.

     Just checkin, don't initialize; error if the RCS file does not

     Compute revision from working file keywords.

     Release lock and delete working file.

     Do normal checkin.

     Like '-r', but immediately checkout locked ('co -l') afterwards.

     Like '-l', but checkout unlocked ('co -u').

     Reset working file mtime (relevant for '-l', '-u').

Multiple flags in '-{fiIjklMqru}' may be given, except for '-r', '-l',
'-u', which are mutually exclusive.  For a fully specified revision of
the form 'BR.N', N must be greater than any existing on BR, or BR must
be new.  If REV is omitted, compute it from the last lock ('co -l'),
perhaps starting a new branch.  If there is no lock, use 'DEFBR.(L+1)'.
*Note Revision options::.

     *Note Date option::.  If no DATE specified, use the working file
     modification time.

     Use MSG as the log message.  *Note Log message option::.

     Assign symbolic NAME to the entry.  For '-n', NAME must be new (no
     previous assignment).  For '-N', overwrite any previous assignment.

     *Note Misc common options::.  Set the state.

     *Note Description option::.

     Set the RCS file's modification time to the new revision's time if
     the former precedes the latter and there is a new revision;
     preserve the RCS file's modification time otherwise.

     Use WHO as the author.

     *Note Misc common options::.

File: rcs.info,  Node: co,  Next: ident,  Prev: ci,  Up: Usage

2.3 Invoking co

     rcs co [options] file ...
     (or "co" instead of "rcs co")

The co command retrieves a revision from the RCS file, writing a new
working file.  This operation is also known as "checkout".

     Force overwrite of working file.

     *Note Misc common options::.

     Write to stdout instead of the working file.

     Normal checkout.

     Like '-r', but also lock.

     Like '-l', but unlock.

     Reset working file mtime (relevant for '-l', '-u').

Multiple flags in '-{fIlMpqru}' may be given, except for '-r', '-l',
'-u', which are mutually exclusive.  *Note Revision options::.

     *Note Substitution mode option::.

     *Note Date option::.  Select latest before or on DATE.

     Merge using JOINS, a list of 'REV:REV' pairs.  *NB*: This option is
     obsolete (*note rcsmerge::).

     *Note Misc common options::.  Select matching state.

     Enable "self-same" mode.  In this mode, the owner of a lock is
     unimportant, just that it exists.  Effectively, this prevents you
     from checking out the same revision twice.

          $ whoami

          $ co -l -f z
          RCS/z,v  -->  z
          revision 1.1 (locked)

          $ co -S -l -f z
          RCS/z,v  -->  z
          co: RCS/z,v: Revision 1.1 is already locked by ttn.

     Preserve the modification time on the RCS file even if it changes
     because a lock is added or removed.

     Select matching login WHO.

     *Note Misc common options::.

File: rcs.info,  Node: ident,  Next: merge,  Prev: co,  Up: Usage

2.4 Invoking ident

     ident [options] [file ...]

If no FILE is specified, scan standard input.  The ident command scans
its input for keywords (*note Concepts::), displaying to standard output
what it finds.

     Normally, if no patterns are found for a file, ident emits a
     warning.  This option suppresses the warning.

     Note that '-VN' is _not_ a valid option for ident, in contrast to
     most other RCS commands (*note Misc common options::).

   In addition to the normal keyword pattern, for Subversion 1.2 (and
later) compatibility(1), ident also recognizes patterns having one of
the forms:

     $KEYWORD:: TEXT $
     ;; two colons and space after keyword
     ;; space before ending $

     $KEYWORD:: TEXT#$
     ;; two colons and space after keyword
     ;; hash before ending $

   ---------- Footnotes ----------

   (1) The "fixed-length keyword syntax" is described in detail in
Version Control with Subversion, chapter "Advanced Topics", section
"Keyword Substitution".

File: rcs.info,  Node: merge,  Next: rcs,  Prev: ident,  Up: Usage

2.5 Invoking merge

     merge [options] receiving-sibling parent other-sibling

The merge command combines the differences between a the parent and the
other sibling, and the differences between the parent and the receiving
sibling.  It writes the result to the receiving sibling.

     Use 'diff3' '-A', '-E' (default), or '-e', respectively.

     Write to stdout instead of overwriting RECEIVING-SIBLING.

     *Note Misc common options::.  Suppress conflict warnings.

     (up to three times) Specify the conflict labels for

     Note that '-VN' is _not_ a valid option for merge, in contrast to
     most other RCS commands (*note Misc common options::).

File: rcs.info,  Node: rcs,  Next: rcsclean,  Prev: merge,  Up: Usage

2.6 Invoking rcs

The rcs command is unique in the set of RCS programs in that it has two
usages, the modern (for RCS 5.9.0 and later) and the legacy.

2.6.1 modern

     rcs [options] command [command-arg ...]

This rcs usage dispatches to COMMAND, passing along COMMAND-ARG... without

     Display a list of available commands, including a one-line
     description, and exit successfully.

     Display a list of command aliases and exit successfully.

'--help COMMAND'
     Display help for a particular COMMAND and exit successfully.  For
     example, to display help for the legacy interface, use:
          --help frob

2.6.2 legacy

     rcs frob [options] file ...
     (or "rcs" instead of "rcs frob")

This rcs usage performs various administrative operations on the RCS
file, depending on the options given.

     Create and initialize a new RCS file.

     Set strict locking.

     Set non-strict locking.

     Don't send mail when breaking someone else's lock.

     Preserve the modification time on the RCS file unless a revision is

     *Note Misc common options::.

     Append LOGINS (comma-separated list of usernames) to access-list.

     Erase LOGINS (comma-separated list of usernames) from access-list.
     If LOGINS is omitted, clear the access-list.

     Append access-list of FILE-NAME to current access-list.

     Set default branch to that of REV or highest branch on trunk if REV
     is omitted.

     Lock a revision.

     Unlock a revision.

     Set comment leader to STRING.  *NB*: Don't use; obsolete.

     *Note Substitution mode option::.

     Replace log message with MSG.  *Note Log message option::.

     If :REV is omitted, delete symbolic NAME.  Otherwise, associate
     NAME with REV; NAME must be new.

     Like '-n', but overwrite any previous assignment.

     Delete (also known as "outdate") revisions in RANGE:

          single revision

          latest revision on branch BR

          REV1 to REV2 on same branch, inclusive

          beginning of branch to REV

          REV to end of branch

     *Note Misc common options::.  Set state.

     *Note Description option::.  Replace description.

     *Note Misc common options::.

These options have no effect, and are included solely for consistency
with other comamnds (*note Environment::): '-zZONE'.

File: rcs.info,  Node: rcsclean,  Next: rcsdiff,  Prev: rcs,  Up: Usage

2.7 Invoking rcsclean

     rcs clean [options] [file ...]
     (or "rcsclean" instead of "rcs clean")

The rcsclean command removes working files that are not being worked on.
If given '-u', it also unlocks and removes working files that are being
worked on but have not changed.  If no FILE is specified, operate on all
the working files in the current directory.

     Specify revision.

     Unlock if is locked and no differences found.

     Dry run (no act, don't operate).

     *Note Misc common options::.

     *Note Substitution mode option::.

     Preserve the modification time on the RCS file even it changes
     because a lock is removed.

     *Note Misc common options::.

     *Note Date option::.

File: rcs.info,  Node: rcsdiff,  Next: rcsmerge,  Prev: rcsclean,  Up: Usage

2.8 Invoking rcsdiff

     rcs diff [options] file ...
     (or "rcsdiff" instead of "rcs diff")

The rcsdiff command runs diff to compare two revisions in an RCS file.
*Note (diff)Invoking diff::.

     (zero, one, or two times) Name a revision.  If given two revisions
     ('-rREV1 -rREV2'), compare those revisions.  If given only one
     revision ('-rREV'), compare the working file with it.  If given no
     revisions, compare the working file with the latest revision on the
     default branch.

     *Note Substitution mode option::.

     *Note Misc common options::.

     *Note Misc common options::.

     *Note Date option::.

These options have no effect, and are included solely for consistency
with other comamnds (*note Environment::): '-T'.

Additionally, the following options (and their argument, if any) are
passed to the underlying diff command:

     -0, -1, -2, -3, -4, -5, -6, -7, -8, -9, -B, -C, -D, -F, -H, -I,
     -L, -U, -W, -a, -b, -c, -d, -e, -f, -h, -i, -n, -p, -t, -u, -w, -y,
     long options (that start with "--")

(Not all of these options are meaningful.)

File: rcs.info,  Node: rcsmerge,  Next: rlog,  Prev: rcsdiff,  Up: Usage

2.9 Invoking rcsmerge

     rcs merge [options] file
     (or "rcsmerge" instead of "rcs merge")

The rcsmerge command incorporates the changes between two revisions of
an RCS file into the corresponding working file.

     Passed to the diff3 command.  The default if none are specified is
     '-E'.  With '-e', suppress warnings on conflict.  The '-A' style
     generates the most verbose output.  *Note (diff)Invoking diff3::.

     Write to stdout instead of overwriting the working file.

     *Note Misc common options::.

     (one or two times) specify a revision.

One or two revisions must be specified (using '-p', '-q', '-r').  If
only one is specified, the second revision defaults to the latest
revision on the default branch.

     *Note Substitution mode option::.

     *Note Misc common options::.

     *Note Date option::.

These options have no effect, and are included solely for consistency
with other comamnds (*note Environment::): '-T'.

File: rcs.info,  Node: rlog,  Prev: rcsmerge,  Up: Usage

2.10 Invoking rlog

     rcs log [options] file ...
     (or "rlog" instead of "rcs log")

The rlog command displays information about RCS files.

     Ignore RCS files with no locks set.

     Print only the name of the RCS file.

     Print only the "header" information.

     Like '-h', but also include the description.

     Omit symbolic names.

     Select the default branch.

     *Note Date option::.  Select revisions based on timestamp, in the
     range DATES, with spec:

          single revision D or earlier

          between D1 and D2, exclusive

          before D

          after D

     Instead of '<' or '>', you can use '<=' or '>=', respectively, to
     specify inclusive ranges.  DATES may also be a list of
     semicolon-separated specs.

     Select revisions locked by WHO (comma-separated list of usernames)
     only, or by anyone if WHO is omitted.

     Select revisions in REVS, a comma-separated list of range specs,
     one of: REV, 'REV:', ':REV', 'REV1:REV2'.

     *Note Misc common options::.  STATES can also be a comma-separated
     list of states.  Select revisions with specified state(s).

     Select revisions checked in by WHO (comma-separated list of
     usernames), or by the user if WHO is omitted.

     *Note Misc common options::.

     *Note Date option::.

These options have no effect, and are included solely for consistency
with other comamnds (*note Environment::): '-q', '-T'.

File: rcs.info,  Node: Hacking,  Next: GNU FDL,  Prev: Usage,  Up: Top

3 Hacking

This chapter, in contrast to the previous (*note Usage::), is
introspective.  It describes an important aspect of RCS interop with
other programs, and development ideas and methods.

* Menu:

* File format::         What is stored on disk.
* Still missing::       What RCS lacks, perhaps perpetually.
* Reporting bugs::      Sending bug reports and feature suggestions.

File: rcs.info,  Node: File format,  Next: Still missing,  Up: Hacking

3.1 File format

An RCS file's contents are described by the grammar below(1).  Overall,
the format is free-format text.  In most environments RCS uses the ISO
8859/1 encoding: visible graphic characters are (octal) codes 041-176
and 240-377, and whitespace characters are codes 010-015 and 040.
*TODO:*  Discuss or point to encoding compatibility issues.

* Menu:

* comma-v grammar::
* comma-v particulars::

   ---------- Footnotes ----------

   (1) This section is adapted from the 'rcsfile(5)' manpage, written by
Walter F. Tichy.

File: rcs.info,  Node: comma-v grammar,  Next: comma-v particulars,  Up: File format

3.1.1 File format grammar

The meta syntax in this section uses the following conventions: '|'
(U+7C) separates alternatives; '{' (U+7B) and '}' (U+7D) enclose
optional phrases; '{' and '}*' (trailing U+2A) enclose phrases that can
be repeated zero or more times; '{' and '}+' (trailing U+2B) enclose
phrases that must appear at least once and can be repeated; terminal
symbols are in '""' (two U+22).

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

     admin     ::=  "head"         {num} ";"
                    { "branch"     {num} ";" }
                    "access"       {id}* ";"
                    "symbols"      { sym ":" num }* ";"
                    "locks"        { id ":" num }* ";"
                    { "strict" ";" }
                    { "integrity " {intstring} ";" }
                    { "comment"    {string} ";" }
                    { "expand"     {string} ";" }

     delta     ::=  num
                    "date"       num ";"
                    "author"     id ";"
                    "state"      {id} ";"
                    "branches"   {num}* ";"
                    "next"       {num} ";"
                    { "commitid" sym ";" }

     desc      ::=  "desc"  string

     deltatext ::=  num
                    "log"   string
                    "text"  string

     num       ::=  { digit | "." }+

     digit     ::=  "0" through "9"

     id        ::=  { idchar | "." }+

     sym       ::=  {idchar}+

     idchar    ::=  any visible graphic character except special

     special   ::=  "$" | "," | "." | ":" | ";" | "@"

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

     word      ::=  id | num | string | ":"

     intchar   ::=  any character, except @

     thirdp    ::=  "^L" {intchar}*

     intstring ::= "@" {intchar}* {thirdp}* "@"

File: rcs.info,  Node: comma-v particulars,  Prev: comma-v grammar,  Up: File format

3.1.2 Additional particulars of the file format

   * In releases prior to 5.8 (2011-08-30), the grammar included the

          newphrase ::= id word* ";"

     and used it in the 'admin', 'delta' and 'deltatext' productions.
     This allowed third-party programs to interoperate with RCS by
     storing opaque (to RCS) data in the file.

     As of 5.8, in the name of progress (towards more systematic file
     integrity support), the only area reserved for third-party interop
     is in the (string) value of the 'integrity' field, specifically
     after the first formfeed (U+0C).  A further restriction (for all
     programs) is that the 'integrity' value must not contain '@'.

   * Whitespace has no significance except in strings.  However,
     whitespace cannot appear within an 'id', 'num', or 'sym', and an
     RCS file must end with newline (U+0A).  Strings are enclosed by '@'
     (U+40).  If a string contains a '@', it must be doubled; otherwise,
     strings can contain arbitrary binary data.

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

   * 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 'delta' nodes form a tree.  All nodes whose numbers consist of
     a single pair (e.g., 2.3, 2.1, 1.3) 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.,, 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 'delta' nodes 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.  *Note
     Figure 3.1: Example RCS File Organization.

                                       v                        / \
                                   ---------                   /   \
             / \          / \      |       |      / \         /     \
            /   \        /   \     |  2.1  |     /   \       /       \
           /     \      /     \    |       |    /     \     /         \
          /\    /\   |       |   /\   /\
          ---------    ---------   ---------   ---------   -------------
              ^            ^           |           ^             ^
              |            |           |           |             |
              |            |           v           |             |
             / \           |       ---------      / \            |
            /   \          |       \  1.3  /     /   \           |
           /     \         ---------\     /     /     \-----------
          /\      1.3.1       \   /     /\
          ---------                   \ /      ---------
              ^                        |           ^
              |                        |           |
              |                        v           |
              |                    ---------       |
              |                    \  1.2  /       |
              ----------------------\     /---------
            1.2.1                    \   /       1.2.2
                                      \ /
                                   \  1.1  /
                                    \     /
                                     \   /
                                      \ /

     Figure 3.1: The organization of an example RCS file.

File: rcs.info,  Node: Still missing,  Next: Reporting bugs,  Prev: File format,  Up: Hacking

3.2 Still missing

RCS is still missing some features.  The following is an unordered list
of "to-do musings" kept by the RCS maintainers.  If you would like to
hack on an item, *Note Reporting bugs::.

   * Add an option to rcsmerge so that it can use an arbitrary program
     to do the 3-way merge, instead of the default merge.  Likewise for
     rcsdiff and diff.  It should be possible to pass arbitrary options
     to these programs, and to the subsidiary co invocations.

   * Add format options for finer control over the output of ident and
     rlog.  E.g.  there should be an easy way for rlog to output lines
     like 'src/main.c 2.4 wft', one for each locked revision.  rlog
     options should have three orthogonal types: selecting files,
     selecting revisions, and selecting rlog format.

   * Add format options for finer control over the output of keyword
     strings.  E.g.  there should be some way to prepend '@(#)', and
     there should be some way to change '$' to some other character to
     disable further substitution.  These options should make the
     resulting files uneditable, like '-kv'.

   * Add long options, e.g.  '--keyword-substitution'.  Unfortunately
     RCS's option syntax is incompatible with getopt.  Perhaps the best
     way is to overload rcs, e.g., 'rcs diff --keyword-substitution=old
     file' instead of 'rcsdiff -ko file'.

   * 'rlog -rM:N' should work even if M and N have different numbers of
     fields, so long as M is an ancestor of N or vice versa.

   * rcs should evaluate options in order; this allows 'rcs -oS -nS'.

   * Be able to redo your most recent checkin with minor changes.

   * 'co -u' shouldn't complain about a '+w' working file if contents
     don't change.

   * Add a '-' option to take the list of file names from standard
     input.  Perhaps the file names should be null-terminated, not
     newline-terminated, so that those that contain newlines are handled

   * Permit multiple option-filename pairs, e.g., 'co -r1.4 a -r1.5 b'.

   * Add an option to break a symbolic link to an RCS file, instead of
     breaking the hard link that it points to.

   * Add ways to specify the earliest revision, the most recent
     revision, the earliest or latest revision on a particular branch,
     and the parent or child of some other revision.

   * If a user has multiple locks, perhaps ci should fall back on the
     method of 'ci -k' to figure out which revision to use.

   * Add an option to rcsclean to clean directories recursively.

   * Write an rcsck program that repairs corrupted RCS files, much as
     fsck repairs corrupted file systems.  For example, it should remove
     stale lock files.

   * Update the date parser to use the more modern 'getdate.y' by
     Bellovin, Salz, and Berets, or the even more modern 'getdate' by
     Moraes.  None of these getdate implementations are as robust as
     RCS's old warhorse in avoiding problems like arithmetic overflow,
     so they'll have to be fixed first.  (Perhaps we can use gnulib
     module 'getdate'.)

   * Break up the code into a library so that it's easier to write new
     programs that manipulate RCS files, and so that useless code is
     removed from the existing programs.  For example, the rcs command
     contains unnecessary keyword substitution baggage, and the merge
     command can be greatly pruned.

   * Make it easier to use your favorite text editor to edit log
     messages, etc., instead of having to type them in irretrievably at
     the terminal.

   * Let the user specify a search path for default branches, e.g., to
     use L as the default branch if it works, and M otherwise.  Let the
     user require that at least one entry in the search path works.  Let
     the user say that later entries in the search path are read only,
     i.e.  one cannot check in changes to them.  This should be an
     option settable by 'RCSINIT'.

   * Add a way for a user to see which revisions affected which lines.

   * Have 'rlog -nN F' print just the revision number that N translates
     to.  E.g., 'rlog -nB. F' would print the highest revision on the
     branch B. Use this to add an option '-bB' to rcsbranch, to freeze
     the named branch.  This should interact well with default branches.

   * Add a co option that prints the revision number before each line,
     as SCCS's 'get -m' does.  [I implemented this for Emacs 22 as a
     subroutine of 'vc-annotate', q.v.  --ttn]

File: rcs.info,  Node: Reporting bugs,  Prev: Still missing,  Up: Hacking

3.3 Reporting bugs

To report bugs or suggest enhancements for GNU RCS, please visit its
homepage (<http://www.gnu.org/software/rcs/>) to find directions on how
to "file a bug report" online, or send electronic mail to
<help-rcs AT gnu.org>.  (If you use the web interface, you don't need to
also send email, since that is done automatically.)

   For bug reports, please include enough information for the
maintainers to reproduce the problem.  Generally speaking, that means:

   * The RCS version, command(s) and manual section(s) involved.
   * Hardware and operating system names and versions.
   * The contents of any input files necessary to reproduce the bug.
   * The expected behavior and/or output.
   * A description of the problem and samples of any erroneous output.
   * Options you gave to 'configure' other than specifying installation
   * Anything else that you think would be helpful.

   When in doubt whether something is needed or not, include it.  It's
better to include too much than to leave out something important.

   Patches are welcome; if possible, please make them with 'git
format-patch' and include 'ChangeLog' entries (*note (emacs)Change
Log::).  Please follow the existing coding style.

File: rcs.info,  Node: GNU FDL,  Next: Index,  Prev: Hacking,  Up: Top

Appendix A GNU Free Documentation License

                     Version 1.3, 3 November 2008

     Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.

     Everyone is permitted to copy and distribute verbatim copies
     of this license document, but changing it is not allowed.


     The purpose of this License is to make a manual, textbook, or other
     functional and useful document "free" in the sense of freedom: to
     assure everyone the effective freedom to copy and redistribute it,
     with or without modifying it, either commercially or
     noncommercially.  Secondarily, this License preserves for the
     author and publisher a way to get credit for their work, while not
     being considered responsible for modifications made by others.

     This License is a kind of "copyleft", which means that derivative
     works of the document must themselves be free in the same sense.
     It complements the GNU General Public License, which is a copyleft
     license designed for free software.

     We have designed this License in order to use it for manuals for
     free software, because free software needs free documentation: a
     free program should come with manuals providing the same freedoms
     that the software does.  But this License is not limited to
     software manuals; it can be used for any textual work, regardless
     of subject matter or whether it is published as a printed book.  We
     recommend this License principally for works whose purpose is
     instruction or reference.


     This License applies to any manual or other work, in any medium,
     that contains a notice placed by the copyright holder saying it can
     be distributed under the terms of this License.  Such a notice
     grants a world-wide, royalty-free license, unlimited in duration,
     to use that work under the conditions stated herein.  The
     "Document", below, refers to any such manual or work.  Any member
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     You may copy and distribute a Modified Version of the Document
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       A. Use in the Title Page (and on the covers, if any) a title
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       B. List on the Title Page, as authors, one or more persons or
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       C. State on the Title page the name of the publisher of the
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       E. Add an appropriate copyright notice for your modifications
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       H. Include an unaltered copy of this License.

       I. Preserve the section Entitled "History", Preserve its Title,
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       J. Preserve the network location, if any, given in the Document
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       K. For any section Entitled "Acknowledgements" or "Dedications",
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       M. Delete any section Entitled "Endorsements".  Such a section
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       N. Do not retitle any existing section to be Entitled
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       O. Preserve any Warranty Disclaimers.

     If the Modified Version includes new front-matter sections or
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     You may add a section Entitled "Endorsements", provided it contains
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     You may add a passage of up to five words as a Front-Cover Text,
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     The author(s) and publisher(s) of the Document do not by this
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     You may combine the Document with other documents released under
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     In the combination, you must combine any sections Entitled
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     You may make a collection consisting of the Document and other
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     You may extract a single document from such a collection, and
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     A compilation of the Document or its derivatives with other
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     Translation is considered a kind of modification, so you may
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     If a section in the Document is Entitled "Acknowledgements",
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     Preserve its Title (section 1) will typically require changing the
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     You may not copy, modify, sublicense, or distribute the Document
     except as expressly provided under this License.  Any attempt
     otherwise to copy, modify, sublicense, or distribute it is void,
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     However, if you cease all violation of this License, then your
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     Moreover, your license from a particular copyright holder is
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     Termination of your rights under this section does not terminate
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     same material does not give you any rights to use it.


     The Free Software Foundation may publish new, revised versions of
     the GNU Free Documentation License from time to time.  Such new
     versions will be similar in spirit to the present version, but may
     differ in detail to address new problems or concerns.  See

     Each version of the License is given a distinguishing version
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     "Massive Multiauthor Collaboration Site" (or "MMC Site") means any
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     A "Massive Multiauthor Collaboration" (or "MMC") contained in the
     site means any set of copyrightable works thus published on the MMC

     "CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
     license published by Creative Commons Corporation, a not-for-profit
     corporation with a principal place of business in San Francisco,
     California, as well as future copyleft versions of that license
     published by that same organization.

     "Incorporate" means to publish or republish a Document, in whole or
     in part, as part of another Document.

     An MMC is "eligible for relicensing" if it is licensed under this
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     License somewhere other than this MMC, and subsequently
     incorporated in whole or in part into the MMC, (1) had no cover
     texts or invariant sections, and (2) were thus incorporated prior
     to November 1, 2008.

     The operator of an MMC Site may republish an MMC contained in the
     site under CC-BY-SA on the same site at any time before August 1,
     2009, provided the MMC is eligible for relicensing.

ADDENDUM: How to use this License for your documents

To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:

       Copyright (C)  YEAR  YOUR NAME.
       Permission is granted to copy, distribute and/or modify this document
       under the terms of the GNU Free Documentation License, Version 1.3
       or any later version published by the Free Software Foundation;
       with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
       Texts.  A copy of the license is included in the section entitled ``GNU
       Free Documentation License''.

   If you have Invariant Sections, Front-Cover Texts and Back-Cover
Texts, replace the "with...Texts." line with this:

         with the Invariant Sections being LIST THEIR TITLES, with
         the Front-Cover Texts being LIST, and with the Back-Cover Texts
         being LIST.

   If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the

   If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of free
software license, such as the GNU General Public License, to permit
their use in free software.

File: rcs.info,  Node: Index,  Prev: GNU FDL,  Up: Top


* Menu:

* access control policy:                 Concepts.            (line  85)
* Author:                                Concepts.            (line 119)
* author, specifying:                    Misc common options. (line  63)
* behavior prior to version 5:           Misc common options. (line  49)
* behavior, version 3:                   Misc common options. (line  60)
* behavior, version 4:                   Misc common options. (line  56)
* binary-old-keyword-value substitution mode: Substitution mode option.
                                                              (line  34)
* branch growth:                         Revision options.    (line  19)
* branch number:                         Concepts.            (line  46)
* branch tip:                            Concepts.            (line  61)
* branch, default:                       Concepts.            (line  79)
* bug reporting:                         Reporting bugs.      (line   6)
* case sensitivity, file format:         comma-v particulars. (line  27)
* checkin:                               Concepts.            (line  97)
* checklist for bug reports:             Reporting bugs.      (line  12)
* checkout:                              Concepts.            (line 106)
* checkout, implicit:                    Quick tour.          (line  84)
* ci invocation:                         ci.                  (line   6)
* co invocation:                         co.                  (line   6)
* comma-v file format:                   Overview.            (line   6)
* command help:                          Common elements.     (line   6)
* command version:                       Common elements.     (line   6)
* command-line option to specify a revision: Revision options.
                                                              (line   6)
* credits:                               Credits.             (line   6)
* Date:                                  Concepts.            (line 122)
* date formats:                          Date option.         (line   6)
* date, specifying:                      Date option.         (line   6)
* dates, file format:                    comma-v particulars. (line  30)
* default branch:                        Concepts.            (line  79)
* default branch, setting:               rcs.                 (line  68)
* deleting revisions:                    rcs.                 (line  94)
* description of working file:           Concepts.            (line  36)
* description text, specifying:          Description option.  (line   6)
* empty log message:                     Log message option.  (line   7)
* emulation, previous RCS versions:      Misc common options. (line  44)
* encoding, file format:                 File format.         (line   6)
* environment variables:                 Environment.         (line   6)
* features, still missing:               Still missing.       (line   6)
* file names on the command-line:        Common elements.     (line  26)
* format, RCSfile:                       File format.         (line   6)
* grammar, file format:                  comma-v grammar.     (line   6)
* Header:                                Concepts.            (line 126)
* history:                               Credits.             (line   6)
* Id:                                    Concepts.            (line 131)
* ident invocation:                      ident.               (line   6)
* implicit checkout, circumstance:       Quick tour.          (line  84)
* implicit checkout, locked:             ci.                  (line  35)
* implicit checkout, unlocked:           ci.                  (line  38)
* instantiating a working file:          Concepts.            (line  27)
* interaction model:                     Concepts.            (line   9)
* interaction model <1>:                 Concepts.            (line   9)
* interactive mode:                      Misc common options. (line   8)
* invocation, ci:                        ci.                  (line   6)
* invocation, co:                        co.                  (line   6)
* invocation, ident:                     ident.               (line   6)
* invocation, merge:                     merge.               (line   6)
* invocation, rcs:                       rcs.                 (line  12)
* invocation, rcs <1>:                   rcs.                 (line  32)
* invocation, rcsclean:                  rcsclean.            (line   6)
* invocation, rcsdiff:                   rcsdiff.             (line   6)
* invocation, rcsmerge:                  rcsmerge.            (line   6)
* invocation, rlog:                      rlog.                (line   6)
* keyword-only substitution mode:        Substitution mode option.
                                                              (line  22)
* keyword-value substitution mode:       Substitution mode option.
                                                              (line  11)
* keyword-value-locker substitution mode: Substitution mode option.
                                                              (line  18)
* keywords, table of:                    Concepts.            (line 119)
* layout of nodes, file format:          comma-v particulars. (line  38)
* license:                               Overview.            (line   6)
* Locker:                                Concepts.            (line 135)
* locking a revision:                    rcs.                 (line  72)
* locking on implicit checkout:          ci.                  (line  35)
* locking, non-strict:                   Quick tour.          (line  69)
* locking, set non-strict:               rcs.                 (line  44)
* locking, set strict:                   rcs.                 (line  41)
* locking, strict:                       Quick tour.          (line  69)
* locks in RCS file:                     Concepts.            (line  85)
* Log:                                   Concepts.            (line 139)
* log message, empty:                    Log message option.  (line   7)
* LOGNAME:                               Environment.         (line  50)
* memory limit:                          Environment.         (line  26)
* merge invocation:                      merge.               (line   6)
* model, interaction:                    Concepts.            (line   9)
* Name:                                  Concepts.            (line 171)
* names, symbolic:                       Concepts.            (line  79)
* node layout, file format:              comma-v particulars. (line  38)
* non-strict locking:                    Quick tour.          (line  69)
* number, branch:                        Concepts.            (line  46)
* number, revision:                      Concepts.            (line  46)
* old-keyword-value substitution mode:   Substitution mode option.
                                                              (line  28)
* order of options and file names:       Common elements.     (line  20)
* outdating revisions:                   rcs.                 (line  94)
* overview:                              Overview.            (line   6)
* pairing RCS and working files:         Common elements.     (line  26)
* patches, contributing:                 Reporting bugs.      (line  27)
* problems:                              Reporting bugs.      (line   6)
* projects, related:                     Overview.            (line  18)
* quiet mode:                            Misc common options. (line  18)
* range of revisions, specifying:        Revision options.    (line  30)
* RCS file:                              Concepts.            (line  36)
* rcs invocation:                        rcs.                 (line  12)
* rcs invocation <1>:                    rcs.                 (line  32)
* RCS version emulation:                 Misc common options. (line  44)
* rcsclean invocation:                   rcsclean.            (line   6)
* rcsdiff invocation:                    rcsdiff.             (line   6)
* RCSfile:                               Concepts.            (line 176)
* RCSfile format:                        File format.         (line   6)
* RCSINIT:                               Environment.         (line   8)
* rcsmerge invocation:                   rcsmerge.            (line   6)
* RCS_MEM_LIMIT:                         Environment.         (line  25)
* removing revisions:                    rcs.                 (line  94)
* reporting bugs:                        Reporting bugs.      (line   6)
* Revision:                              Concepts.            (line 179)
* revision number:                       Concepts.            (line  46)
* revision range, specifying:            Revision options.    (line  30)
* revision, specifying:                  Revision options.    (line   6)
* revisions, tree of:                    Concepts.            (line  79)
* rlog invocation:                       rlog.                (line   6)
* Source:                                Concepts.            (line 182)
* specifying a date:                     Date option.         (line   6)
* specifying a range of revisions:       Revision options.    (line  30)
* specifying a revision:                 Revision options.    (line   6)
* specifying a state:                    Misc common options. (line  22)
* specifying a suffix list:              Misc common options. (line  67)
* specifying a time/date:                Date option.         (line   6)
* specifying author:                     Misc common options. (line  63)
* specifying description text:           Description option.  (line   6)
* specifying substitution mode:          Substitution mode option.
                                                              (line   6)
* State:                                 Concepts.            (line 185)
* state, specifying:                     Misc common options. (line  22)
* strict locking:                        Quick tour.          (line  69)
* substitution mode, default:            Substitution mode option.
                                                              (line  11)
* substitution mode, specifying:         Substitution mode option.
                                                              (line   6)
* suffix list, specifying:               Misc common options. (line  67)
* symbolic names:                        Concepts.            (line  79)
* TEMP:                                  Environment.         (line  43)
* third-party interop, file format:      comma-v particulars. (line   6)
* Tichy, Walter F.:                      Credits.             (line   6)
* time zone:                             Date option.         (line   6)
* time/date, specifying:                 Date option.         (line   6)
* tip:                                   Concepts.            (line  61)
* tip increment:                         Revision options.    (line  19)
* TMP:                                   Environment.         (line  42)
* TMPDIR:                                Environment.         (line  41)
* tree of revisions:                     Concepts.            (line  79)
* unlocking a revision:                  rcs.                 (line  75)
* USER:                                  Environment.         (line  51)
* value-only substitution mode:          Substitution mode option.
                                                              (line  41)
* whitespace, file format:               comma-v particulars. (line  21)
* working file, description:             Concepts.            (line  36)
* working file, instantiation:           Concepts.            (line  27)

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