GNU GENERAL PUBLIC LICENSE
**************************

Version 2, June 1991

     Copyright © 1989, 1991 Free Software Foundation, Inc.
     675 Mass Ave, Cambridge, MA 02139, USA

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

Preamble
========

The licenses for most software are designed to take away your freedom to share and change it.  By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software---to make sure the software is free for all its users.  This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it.  (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.)  You can apply it to your programs, too.

When we speak of free software, we are referring to freedom, not price.  Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things.

To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it.

For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have.  You must make sure that they, too, receive or can get the source code.  And you must show them these terms so they know their rights.

We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software.

Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software.  If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations.

Finally, any free program is threatened constantly by software patents.  We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary.  To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all.

The precise terms and conditions for copying, distribution and modification follow.

TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

 0. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License.  The ``Program'', below, refers to any such program or work, and a ``work based on the Program'' means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language.  (Hereinafter, translation is included without limitation in the term ``modification''.)  Each licensee is addressed as ``you''.

     Activities other than copying, distribution and modification are not covered by this License; they are outside its scope.  The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does.

 1. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program.

     You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee.

 2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions:

      a. You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change.

      b. You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License.

      c. If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License.  (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.)

     These requirements apply to the modified work as a whole.  If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works.  But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it.

     Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program.

     In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License.

 3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following:

      a. Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,

      b. Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,

      c. Accompany it with the information you received as to the offer to distribute corresponding source code.  (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.)

     The source code for a work means the preferred form of the work for making modifications to it.  For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable.  However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable.

     If distribution of executable or object code is made by offering access to copy from a designated place, then offering equivalent access to copy the source code from the same place counts as distribution of the source code, even though third parties are not compelled to copy the source along with the object code.

 4. You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License.  Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.

 5. You are not required to accept this License, since you have not signed it.  However, nothing else grants you permission to modify or distribute the Program or its derivative works.  These actions are prohibited by law if you do not accept this License.  Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it.

 6. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions.  You may not impose any further restrictions on the recipients' exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties to this License.

 7. If, as a consequence of a court judgment or allegation of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License.  If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all.  For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program.

     If any portion of this section is held invalid or unenforceable under any particular circumstance, the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances.

     It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of the free software distribution system, which is implemented by public license practices.  Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system; it is up to the author/donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice.

     This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License.

 8. If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded.  In such case, this License incorporates the limitation as if written in the body of this License.

 9. The Free Software Foundation may publish revised and/or new versions of the General Public 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.

     Each version is given a distinguishing version number.  If the Program specifies a version number of this License which applies to it and ``any later version'', you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation.  If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation.

 10. If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission.  For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this.  Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally.

     NO WARRANTY

 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM ``AS IS'' WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.

 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

END OF TERMS AND CONDITIONS

How to Apply These Terms to Your New Programs
=============================================

If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.

To do so, attach the following notices to the program.  It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the ``copyright'' line and a pointer to where the full notice is found.

     ONE LINE TO GIVE THE PROGRAM'S NAME AND AN IDEA OF WHAT IT DOES.
     Copyright (C) 19YY  NAME OF AUTHOR

     This program is free software; you can redistribute it and/or
     modify it under the terms of the GNU General Public License
     as published by the Free Software Foundation; either version 2
     of the License, or (at your option) any later version.

     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

Also add information on how to contact you by electronic and paper mail.

If the program is interactive, make it output a short notice like this when it starts in an interactive mode:

     Gnomovision version 69, Copyright (C) 19YY NAME OF AUTHOR
     Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
     type `show w'.  This is free software, and you are welcome
     to redistribute it under certain conditions; type `show c'
     for details.

The hypothetical commands show w and show c should show the appropriate parts of the General Public License.  Of course, the commands you use may be called something other than show w and show c; they could even be mouse-clicks or menu items---whatever suits your program.

You should also get your employer (if you work as a programmer) or your school, if any, to sign a ``copyright disclaimer'' for the program, if necessary.  Here is a sample; alter the names:

     Yoyodyne, Inc., hereby disclaims all copyright
     interest in the program `Gnomovision'
     (which makes passes at compilers) written
     by James Hacker.

     SIGNATURE OF TY COON, 1 April 1989
     Ty Coon, President of Vice

This General Public License does not permit incorporating your program into proprietary programs.  If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library.  If this is what you want to do, use the GNU Library General Public License instead of this License.

Introduction
************

Most of the GNU Emacs text editor is written in the programming language called Emacs Lisp.  You can write new code in Emacs Lisp and install it as an extension to the editor.  However, Emacs Lisp is more than a mere ``extension language''; it is a full computer programming language in its own right.  You can use it as you would any other programming language.

Because Emacs Lisp is designed for use in an editor, it has special features for scanning and parsing text as well as features for handling files, buffers, displays, subprocesses, and so on.  Emacs Lisp is closely integrated with the editing facilities; thus, editing commands are functions that can also conveniently be called from Lisp programs, and parameters for customization are ordinary Lisp variables.

This manual describes Emacs Lisp, presuming considerable familiarity with the use of Emacs for editing.  (See The GNU Emacs Manual for this basic information.)  Generally speaking, the earlier chapters describe features of Emacs Lisp that have counterparts in many programming languages, and later chapters describe features that are peculiar to Emacs Lisp or relate specifically to editing.

This is edition 2.5.

Caveats
=======

This manual has gone through numerous drafts.  It is nearly complete but not flawless.  There are a few topics that are not covered, either because we consider them secondary (such as most of the individual modes) or because they are yet to be written.  Because we are not able to deal with them completely, we have left out several parts intentionally.  This includes most information about usage on VMS.

The manual should be fully correct in what it does cover, and it is therefore open to criticism on anything it says---from specific examples and descriptive text, to the ordering of chapters and sections.  If something is confusing, or you find that you have to look at the sources or experiment to learn something not covered in the manual, then perhaps the manual should be fixed.  Please let us know.

As you use this manual, we ask that you send corrections as soon as you find them.  If you think of a simple, real life example for a function or group of functions, please make an effort to write it up and send it in.  Please reference any comments to the node name and function or variable name, as appropriate.  Also state the number of the edition which you are criticizing.

Please mail comments and corrections to

     bug-lisp-manual@prep.ai.mit.edu

We let mail to this list accumulate unread until someone decides to apply the corrections.  Months, and sometimes years, go by between updates.  So please attach no significance to the lack of a reply---your mail will be acted on in due time.  If you want to contact the Emacs maintainers more quickly, send mail to bug-gnu-emacs@prep.ai.mit.edu.

      --Bil Lewis, Dan LaLiberte, Richard Stallman

Lisp History
============

Lisp (LISt Processing language) was first developed in the late 1950's at the Massachusetts Institute of Technology for research in artificial intelligence.  The great power of the Lisp language makes it superior for other purposes as well, such as writing editing commands.

Dozens of Lisp implementations have been built over the years, each with its own idiosyncrasies.  Many of them were inspired by Maclisp, which was written in the 1960's at MIT's Project MAC.  Eventually the implementors of the descendants of Maclisp came together and developed a standard for Lisp systems, called Common Lisp.  In the mean time, Gerry Sussman and Guy Steele at MIT developed a simplified but very powerful dialect of Lisp, called Scheme.

GNU Emacs Lisp is largely inspired by Maclisp, and a little by Common Lisp.  If you know Common Lisp, you will notice many similarities. However, many of the features of Common Lisp have been omitted or simplified in order to reduce the memory requirements of GNU Emacs. Sometimes the simplifications are so drastic that a Common Lisp user might be very confused.  We will occasionally point out how GNU Emacs Lisp differs from Common Lisp.  If you don't know Common Lisp, don't worry about it; this manual is self-contained.

Emacs Lisp is not at all influenced by Scheme; but the GNU project has an implementation of Scheme, called Guile.  We use Guile for extensibility in all new GNU software that calls for extensibility.

Conventions
===========

This section explains the notational conventions that are used in this manual.  You may want to skip this section and refer back to it later.

Some Terms
----------

Throughout this manual, the phrases ``the Lisp reader'' and ``the Lisp printer'' are used to refer to those routines in Lisp that convert textual representations of Lisp objects into actual Lisp objects, and vice versa.  See Printed Representation, for more details.  You, the person reading this manual, are thought of as ``the programmer'' and are addressed as ``you''.  ``The user'' is the person who uses Lisp programs, including those you write.

Examples of Lisp code appear in this font or form: (list 1 2 3).  Names that represent metasyntactic variables, or arguments to a function being described, appear in this font or form: FIRST-NUMBER.

nil and t
---------

In Lisp, the symbol nil has three separate meanings: it is a symbol with the name nil; it is the logical truth value FALSE; and it is the empty list---the list of zero elements. When used as a variable, nil always has the value nil.

As far as the Lisp reader is concerned, () and nil are identical: they stand for the same object, the symbol nil.  The different ways of writing the symbol are intended entirely for human readers.  After the Lisp reader has read either () or nil, there is no way to determine which representation was actually written by the programmer.

In this manual, we use () when we wish to emphasize that it means the empty list, and we use nil when we wish to emphasize that it means the truth value FALSE.  That is a good convention to use in Lisp programs also.

     (cons 'foo ())                ; Emphasize the empty list
     (not nil)                     ; Emphasize the truth value FALSE

In contexts where a truth value is expected, any non-nil value is considered to be TRUE.  However, t is the preferred way to represent the truth value TRUE.  When you need to choose a value which represents TRUE, and there is no other basis for choosing, use t.  The symbol t always has value t.

In Emacs Lisp, nil and t are special symbols that always evaluate to themselves.  This is so that you do not need to quote them to use them as constants in a program.  An attempt to change their values results in a setting-constant error.  The same is true of any symbol whose name starts with a colon (:).  See Constant Variables.

Evaluation Notation
-------------------

A Lisp expression that you can evaluate is called a form. Evaluating a form always produces a result, which is a Lisp object.  In the examples in this manual, this is indicated with =>:

     (car '(1 2))
          => 1

You can read this as ``(car '(1 2)) evaluates to 1''.

When a form is a macro call, it expands into a new form for Lisp to evaluate.  We show the result of the expansion with ==>.  We may or may not show the actual result of the evaluation of the expanded form.

     (third '(a b c))
          ==> (car (cdr (cdr '(a b c))))
          => c

Sometimes to help describe one form we show another form that produces identical results.  The exact equivalence of two forms is indicated with ==.

     (make-sparse-keymap) == (list 'keymap)

Printing Notation
-----------------

Many of the examples in this manual print text when they are evaluated.  If you execute example code in a Lisp Interaction buffer (such as the buffer *scratch*), the printed text is inserted into the buffer.  If you execute the example by other means (such as by evaluating the function eval-region), the printed text is displayed in the echo area.  You should be aware that text displayed in the echo area is truncated to a single line.

Examples in this manual indicate printed text with -|, irrespective of where that text goes.  The value returned by evaluating the form (here bar) follows on a separate line.

     (progn (print 'foo) (print 'bar))
          -| foo
          -| bar
          => bar

Error Messages
--------------

Some examples signal errors.  This normally displays an error message in the echo area.  We show the error message on a line starting with error-->.  Note that error--> itself does not appear in the echo area.

     (+ 23 'x)
     error--> Wrong type argument: number-or-marker-p, x

Buffer Text Notation
--------------------

Some examples show modifications to text in a buffer, with ``before'' and ``after'' versions of the text.  These examples show the contents of the buffer in question between two lines of dashes containing the buffer name.  In addition, -!- indicates the location of point. (The symbol for point, of course, is not part of the text in the buffer; it indicates the place between two characters where point is currently located.)

     ---------- Buffer: foo ----------
     This is the -!-contents of foo.
     ---------- Buffer: foo ----------

     (insert "changed ")
          => nil
     ---------- Buffer: foo ----------
     This is the changed -!-contents of foo.
     ---------- Buffer: foo ----------

Format of Descriptions
----------------------

Functions, variables, macros, commands, user options, and special forms are described in this manual in a uniform format.  The first line of a description contains the name of the item followed by its arguments, if any. The category---function, variable, or whatever---appears at the beginning of the line. The description follows on succeeding lines, sometimes with examples.

A Sample Function Description
.............................

In a function description, the name of the function being described appears first.  It is followed on the same line by a list of argument names.  These names are also used in the body of the description, to stand for the values of the arguments.

The appearance of the keyword &optional in the argument list indicates that the subsequent arguments may be omitted (omitted arguments default to nil).  Do not write &optional when you call the function.

The keyword &rest (which will always be followed by a single argument name) indicates that any number of arguments can follow.  The value of the single following arguments name will be a list of all these arguments. Do not write &rest when you call the function.

Here is a description of an imaginary function foo:

 -- Function: foo integer1 &optional integer2 &rest integers
     The function foo subtracts INTEGER1 from INTEGER2, then adds all the rest of the arguments to the result.  If INTEGER2 is not supplied, then the number 19 is used by default.

          (foo 1 5 3 9)
               => 16
          (foo 5)
               => 14

     More generally,

          (foo W X Y...)
          ==
          (+ (- X W) Y...)

Any argument whose name contains the name of a type (e.g., INTEGER, INTEGER1 or BUFFER) is expected to be of that type.  A plural of a type (such as BUFFERS) often means a list of objects of that type.  Arguments named OBJECT may be of any type. (see Lisp Data Types, for a list of Emacs object types.)  Arguments with other sorts of names (e.g., NEW-FILE) are discussed specifically in the description of the function.  In some sections, features common to the arguments of several functions are described at the beginning.

See Lambda Expressions, for a more complete description of optional and rest arguments.

Command, macro, and special form descriptions have the same format, but the word `Function' is replaced by `Command', `Macro', or `Special Form', respectively.  Commands are simply functions that may be called interactively; macros process their arguments differently from functions (the arguments are not evaluated), but are presented the same way.

Special form descriptions use a more complex notation to specify optional and repeated arguments because they can break the argument list down into separate arguments in more complicated ways. [OPTIONAL-ARG] means that OPTIONAL-ARG is optional and REPEATED-ARGS... stands for zero or more arguments.  Parentheses are used when several arguments are grouped into additional levels of list structure.  Here is an example:

 -- Special Form: count-loop (VAR [FROM TO [INC]]) BODY...
     This imaginary special form implements a loop that executes the BODY forms and then increments the variable VAR on each iteration.  On the first iteration, the variable has the value FROM; on subsequent iterations, it is incremented by 1 (or by INC if that is given).  The loop exits before executing BODY if VAR equals TO.  Here is an example:

          (count-loop (i 0 10)
            (prin1 i) (princ " ")
            (prin1 (aref vector i))
            (terpri))

     If FROM and TO are omitted, then VAR is bound to nil before the loop begins, and the loop exits if VAR is non-nil at the beginning of an iteration.  Here is an example:

          (count-loop (done)
            (if (pending)
                (fixit)
              (setq done t)))

     In this special form, the arguments FROM and TO are optional, but must both be present or both absent.  If they are present, INC may optionally be specified as well.  These arguments are grouped with the argument VAR into a list, to distinguish them from BODY, which includes all remaining elements of the form.

A Sample Variable Description
.............................

A variable is a name that can hold a value.  Although any variable can be set by the user, certain variables that exist specifically so that users can change them are called user options.  Ordinary variables and user options are described using a format like that for functions except that there are no arguments.

Here is a description of the imaginary electric-future-map variable.

 -- Variable: electric-future-map
     The value of this variable is a full keymap used by Electric Command Future mode.  The functions in this map allow you to edit commands you have not yet thought about executing.

User option descriptions have the same format, but `Variable' is replaced by `User Option'.

Version Information
===================

These functions and variables provide information about which version of Emacs is in use.

 -- Command: emacs-version
     This function returns a string describing the version of Emacs that is running.  It is useful to include this string in bug reports.

          (emacs-version)
            => "GNU Emacs 20.3.5 (i486-pc-linux-gnulibc1, X toolkit)
           of Sat Feb 14 1998 on psilocin.gnu.org"

     Called interactively, the function prints the same information in the echo area.

 -- Variable: emacs-build-time
     The value of this variable is the time at which Emacs was built at the local site.

          emacs-build-time
               => "Tue Jun  6 14:55:57 1995"

 -- Variable: emacs-version
     The value of this variable is the version of Emacs being run.  It is a string such as "20.3.1".  The last number in this string is not really part of the Emacs release version number; it is incremented each time you build Emacs in any given directory.

The following two variables have existed since Emacs version 19.23,

 -- Variable: emacs-major-version
     The major version number of Emacs, as an integer.  For Emacs version 20.3, the value is 20.

 -- Variable: emacs-minor-version
     The minor version number of Emacs, as an integer.  For Emacs version 20.3, the value is 3.

Acknowledgements
================

This manual was written by Robert Krawitz, Bil Lewis, Dan LaLiberte, Richard M. Stallman and Chris Welty, the volunteers of the GNU manual group, in an effort extending over several years.  Robert J. Chassell helped to review and edit the manual, with the support of the Defense Advanced Research Projects Agency, ARPA Order 6082, arranged by Warren A. Hunt, Jr. of Computational Logic, Inc.

Corrections were supplied by Karl Berry, Jim Blandy, Bard Bloom, Stephane Boucher, David Boyes, Alan Carroll, Richard Davis, Lawrence R. Dodd, Peter Doornbosch, David A. Duff, Chris Eich, Beverly Erlebacher, David Eckelkamp, Ralf Fassel, Eirik Fuller, Stephen Gildea, Bob Glickstein, Eric Hanchrow, George Hartzell, Nathan Hess, Masayuki Ida, Dan Jacobson, Jak Kirman, Bob Knighten, Frederick M. Korz, Joe Lammens, Glenn M. Lewis, K. Richard Magill, Brian Marick, Roland McGrath, Skip Montanaro, John Gardiner Myers, Thomas A. Peterson, Francesco Potorti, Friedrich Pukelsheim, Arnold D. Robbins, Raul Rockwell, Per Starback, Shinichirou Sugou, Kimmo Suominen, Edward Tharp, Bill Trost, Rickard Westman, Jean White, Matthew Wilding, Carl Witty, Dale Worley, Rusty Wright, and David D. Zuhn.