This file describes info relevant to beta versions of XEmacs.

Copyright © 2005 Ben Wing. Copyright © 2005 Free Software Foundation, Inc.

This file is part of XEmacs.

XEmacs 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, or (at your option) any later version.

XEmacs 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 XEmacs; see the file COPYING.  If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

This Info file describes info relevant to beta versions of XEmacs.

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

You are running a potentially unstable version of XEmacs.  Please do not report problems with Beta XEmacs to comp.emacs.xemacs.  Report them to mailto:xemacs-beta@xemacs.org, preferably with M-x report-xemacs-bug RET.

Mailing Lists
=============

XEmacs Beta Mailing List
------------------------

If you are not subscribed to the XEmacs beta list you should be. Currently all discussion of development issues, including bug reports and coding discussion, takes place on the XEmacs Beta mailing list. Only patches and administrative actions regarding patches are sent elsewhere (to the XEmacs Patches list).

XEmacs Patches Mailing List
---------------------------

XEmacs Patches records proposed changes to XEmacs, and their disposition.  It is open subscription, and all patches that are seriously proposed for inclusion in XEmacs should be posted here.  You can follow progress of your patch by subscribing to the mailing list or in the archives.

Besides patches, only actions by members of the XEmacs Review Board should be posted to this list.  All discussion should be redirected to XEmacs Beta or XEmacs Design.

XEmacs Design Mailing List
--------------------------

XEmacs Design is for design discussions such as adding major features or whole modules, or reimplementation of existing functions, to XEmacs.

List Administrivia
------------------

In the descriptions below, the word LIST (all uppercase) is a variable.  Substitute "beta", "design", or "patches" as appropriate (to get "xemacs-beta" as the mailbox for the XEmacs Beta mailing list, or http://www.xemacs.org/Lists/#xemacs-beta for its URL).

The XEmacs mailing lists are managed by the Mailman mailing list package, and the usual Mailman commands work.  Do not send mailing list requests to the main address (mailto:xemacs-LIST@xemacs.org), always send them to mailto:xemacs-LIST-request@xemacs.org.  If you have problems with the list itself, they should be brought to the attention of the XEmacs Mailing List manager mailto:list-manager@xemacs.org (the same mailbox, "list-manager", for all lists).  All public mailing lists have searchable archives.  The URL is

http://list-archive.xemacs.org/xemacs-LIST

Note that the xemacs-LIST-admin address is used internally by the Mailman software; it is NOT a synonym for xemacs-LIST-request.

Managing your subscription via the Web
--------------------------------------

Subscription, unsubscription, and options (such as digests and temporarily suspending delivery) can be accomplished via the web interface at http://www.xemacs.org/Lists/#xemacs-LIST.

Subscribing by e-mail
---------------------

Send an email message to mailto:xemacs-LIST-request@xemacs.org with subscribe (without the quotes) as the BODY of the message.

Unsubscribing by e-mail
-----------------------

Send an email message to mailto:xemacs-LIST-request@xemacs.org with unsubscribe (without the quotes) as the BODY of the message.

Beta Release Schedule
=====================

We would like to achieve a weekly or fortnightly release cycle (you know the Open Source model: release early, release often), and in a perfect world that would indeed be the case.  There are at least three things that often get in the way of that goal: 1) The Release Manager has a life outside of XEmacs (hard to believe, I know, but true), 2) we like to make releases that will build (at least on the Release Manager's box), and 3) Murphy likes to throw a spanner in the works right when you least expect it (Murphy's Law: Whatever can go wrong, will go wrong).

If you'd like to keep right up to date and ride the bleeding edge, use CVS (see http://www.xemacs.org/Develop/cvsaccess.html).  If you can't use CVS for some reason and must use FTP, please let us know. it will make it more likely that we release betas more often.

Reporting Problems
==================

The best way to get problems fixed in XEmacs is to submit good problem reports, M-x report-xemacs-bug RET will help you do this (assuming you have a usable XEmacs).  Since this is beta software, problems are certain to exist.  Please read through all of part II of the XEmacs FAQ for an overview of problem reporting.  Other items which are most important are:

 1. Do not submit C stack backtraces without line numbers.  Since it is possible to compile optimized with debug information with GCC it is never a good idea to compile XEmacs without the -g flag. XEmacs runs on a variety of platforms, and often it is not possible to recreate problems which afflict a specific platform. The line numbers in the C stack backtrace help isolate where the problem is actually occurring.

 2. Attempt to recreate the problem starting with an invocation of XEmacs with xemacs -no-autoloads.  Quite often, problems are due to package interdependencies, and the like.  An actual bug in XEmacs should be reproducible in a default configuration without loading any special packages (or the one or two specific packages that cause the bug to appear).  If you have trouble getting anything to work at all with the above invocation, use xemacs -vanilla instead.  If you need to load your user init file or the site file to get the problem to occur, then it has something to do with them, and you should try to isolate the issue in those files.

 3. A picture can be worth a thousand words.  When reporting an unusual display, it is generally best to capture the problem in a screen dump and include that with the problem report.  The easiest way to get a screen dump is to use the xv program and its grab function.  Save the image as a GIF to keep bandwidth requirements down without loss of information.  MIME is the preferred method for making the image attachments.

Getting the Source
==================

In addition to the normal tar distribution, XEmacs source is now available via CVS.  Please see

http://www.xemacs.org/Develop/cvsaccess.html

Compiling Beta XEmacs
*********************

Building an XEmacs from patches
===============================

All beta releases of XEmacs are included with patches from the previous version in an attempt to keep bandwidth requirements down.  Patches should be applied with the GNU patch program in something like the following.  Let's say you're upgrading XEmacs 21.5-beta9 to XEmacs 21.5-beta10 and you have a full unmodified XEmacs 21.5-beta9 source tree to work with.  Change to the top level directory and issue the shell command:

     $ gunzip -c /tmp/xemacs-21.5.9-21.5.10.patch.gz | patch -p1

After patching, check to see that no patches were missed by doing

     $ find . -name \*.rej -print

Any rejections should be treated as serious problems to be resolved before building XEmacs.

After seeing that there were no rejections, issue the commands

     $ ./config.status --recheck
     $ make beta > ./beta.err 2>&1
     $ make check > ./xemacs-make-check.err 2>&1

Redirect the output from make to those files because you'll use them later when you send off a build report with M-x build-report RET

Building XEmacs from a full distribution
========================================

 1. Locate a convenient place where you have at least 100MB of free space and issue the command

          $ gunzip -c /tmp/xemacs-21.5.10.tar.gz | tar xvf -

     (or simply tar zxvf /tmp/xemacs-21.5.10.tar.gz if you use GNU tar).

 2. cd to the top level directory and issue an appropriate configure command.

 3. Run configure.  If you are new, just consider running it with no options, to see if you can get a succesful build.  When you are more experienced, you should put various flags in.  Here is what we suggest:

      1. It's a good idea to use

               --enable-debug
               --enable-memory-usage-stats
               --enable-error-checking=all

          These turn on extra debugging info and checks.  The last one in particular will add a great deal of extra error-checking -- which will slow your XEmacs down somewhat but is likely to catch bugs much sooner and make your bug reports much more useful.

      2. You should also strongly consider

               --enable-mule
               --enable-kkcc
               --enable-pdump
               --enable-clash-detection
               --with-wmcommand
               --with-xfs

          These turn on optional features, which can always use testing.

      3. If you have gcc, consider using

               --with-compiler=gcc
               --with-xemacs-compiler=g++

          This will compile XEmacs using g++, which will turn on a lot of additional error-checking.

      4. If your packages are not installed under /usr/local, you should add a line like

               --with-package-path=~/.xemacs::/xemacs/site-packages:/xemacs/xemacs-packages:/xemacs/mule-packages

      5. If you want to build multiple configurations from the same source tree, make separate build directories for each configuration, run configure from the top level of these (currently empty) directories and use an option like

               --srcdir=/xemacs/source-tree

          (or wherever your source tree is).  This will magically create symlinks and populate your build directory.

      6. Use --with-site-prefixes (or --with-site-includes and ---with-site-libraries) if you have some packages that XEmacs can compile with that are located in an unusual place.  For example:

               --with-site-prefixes=/usr/local/pgsql:/usr/local/BerkeleyDB.4.1

      7. Depending on your build environment, consuder setting or not setting options for menubars, scrollbars, window systems, native sound, etc.  If you're not sure, leave them out and let configure do the auto-detection. (If you get bugs compiling GTK, use --with-gtk=no --with-gnome=no.)

          Part of the configure output is a summary that looks something like the following.  (this summary is also available as the file 'Installation' in the top directory of your build tree, and via the command M-x describe-installation RET).

               uname -a: Darwin laptop.local 7.7.0 Darwin Kernel Version 7.7.0: Sun Nov  7 16:06:51 PST 2004; root:xnu/xnu-517.9.5.obj~1/RELEASE_PPC  Power Macintosh powerpc

               ./configure '--with-site-prefixes=/sw' '--without-ldap' '--with-dynamic=yes' '--with-gtk=no' '--with-gnome=no' '--enable-toolbars' '--with-wmcommand' '--with-athena=3d' '--enable-menubars=lucid' '--enable-scrollbars=athena' '--enable-dialogs=athena' '--enable-widgets=athena' '--with-gif' '--enable-sound=native,noesd' '--with-site-lisp=no' '--with-site-modules' '--enable-pdump' '--enable-mule' '--with-xfs' '--enable-debug' '--enable-error-checking=all' '--enable-memory-usage-stats' '--enable-kkcc' '--enable-clash-detection'

               XEmacs 21.5-b19 "chives" (+CVS-20050226) configured for `powerpc-apple-darwin7.7.0'.

                 WARNING: --------------------------------------------------------------
                 WARNING: This was produced from a new autoconf-2.5 based configuration.
                 WARNING: If this configuration seems buggy then copy etc/configure-2.13
                 WARNING: to configure and try again.  Also please report the bug.
                 WARNING: --------------------------------------------------------------

               Compilation Environment and Installation Defaults:
                 Source code location:              /usr/local/src/xemacs
                 Installation prefix:               /usr/local
                 Additional prefixes:               /sw
                 Operating system description file: `s/darwin.h'
                 Machine description file:          `m/powerpc.h'
                 Compiler version:                  gcc (GCC) 3.3 20030304 (Apple Computer, Inc. build 1671)
                   - GCC specs file:                /usr/libexec/gcc/darwin/ppc/3.3/specs
                   - Compiler command:              gcc -Wall -Wno-switch -Wundef -Wsign-compare -Wno-char-subscripts -Wpacked -Wpointer-arith -Wunused-parameter -g
                 libc version:
                 Relocating allocator for buffers:  no
                 GNU version of malloc:             no
                   - The GNU allocators don't work with this system configuration.

               Window System:
                 Compiling in support for the X window system:
                   - X Windows headers location:                 /usr/X11R6/include
                   - X Windows libraries location:               /usr/X11R6/lib
                   - Handling WM_COMMAND properly.
                 Compiling in support for the Athena widget set:
                   - Athena headers location:                    X11/Xaw3d
                   - Athena library to link:                     Xaw3d
                 Using Lucid menubars.
                 Using Athena scrollbars.
                 Using Athena dialog boxes.
                 Using Athena native widgets.

               TTY:
                 Compiling in support for ncurses.

               Images:
                 Compiling in support for GIF  images (builtin).
                 Compiling in support for XPM  images.
                 Compiling in support for PNG  images.
                 Compiling in support for JPEG images.
                 Compiling in support for TIFF images.
                 Compiling in support for X-Face message headers.

               Sound:

               Databases:
                 Compiling in support for Berkeley database.
                 Compiling in support for GNU DBM.
                 Compiling in support for PostgreSQL.
                   - Using PostgreSQL header file:  postgresql/libpq-fe.h
                   - Using PostgreSQL V7 bindings.

               Internationalization:
                 Compiling in support for Mule (multi-lingual Emacs).
                 Compiling in support for XIM (X11R5+ I18N input method).
                   - Using raw Xlib to provide XIM support.
                   - Using XFontSet to provide bilingual menubar.

               Mail:
                 Compiling in support for "file" mail spool file locking method.

               Other Features:
                 Inhibiting IPv6 canonicalization at startup.
                 Compiling in support for dynamic shared object modules.
                 Using the new GC algorithms.
                 Using the new portable dumper.
                 Compiling in support for extra debugging code.
                 Compiling in support for runtime error checking.
                 WARNING: ---------------------------------------------------------
                 WARNING: XEmacs will run noticeably more slowly as a result.
                 WARNING: Error checking is on by default for XEmacs beta releases.
                 WARNING: ---------------------------------------------------------

 4. Then...

          $ make > ./beta.err 2>&1
          $ make check > ./xemacs-make-check.err 2>&1

     ...and you should have a working XEmacs.

 5. After you have verified that you have a functional editor, fire up your favorite mail program and send a build report to mailto:xemacs-buildreports@xemacs.org.

     Preferably this is best done from XEmacs, following these simple steps:

          M-x customize-group RET build-report RET M-x build-report RET

     See also http://www.xemacs.org/Releases/Public-21.2/tester.html#reporting

     If you create the report manually by other means, here is what the build report should include:

      1. Your hardware configuration (OS version, etc.)

      2. Version numbers of software in use (X11 version, system library versions if appropriate, graphics library versions if appropriate). If you're on a system like Linux, include all the version numbers you can because chances are it makes a difference.

      3. The options given to configure

      4. The configuration report illustrated above

          For convenience all of the above items are placed in a file called `Installation' in the top level build directory.  They are also available by performing M-x describe-installation inside XEmacs.

      5. Any other unusual items you feel should be brought to the attention of the developers.

Packages
********

[Note: these instructions have been partly updated, but not carefully reviewed in some time.  Caveat tester.]

Starting with XEmacs 21.1, much of the functionality of XEmacs has been unbundled into "the packages."  For more information about the package system, see the Info nodes on Packages (in the XEmacs User Manual) and on Packaging (in the Lisp Reference).

When bootstrapping XEmacs, you may need to manually install some packages (at least xemacs-base and efs).  These packages are available by FTP at ftp://ftp.xemacs.org/pub/xemacs/packages/.

Binary package installation
===========================

Prerequisite:  XEmacs 21.0-b1.

Binary packages are complete entities that can be untarred at the top level of an XEmacs package hierarchy and work at runtime.  To install files in this directory, run the command M-x package-admin-add-binary-package and fill in appropriate values to the prompts.

Manual procedures for package management
========================================

Prerequisite: XEmacs 21.0

When adding and deleting files from a lisp directory the auto-autoloads.el (global symbols) and custom-load.el (Customization groups) must be kept in synch.  Assuming one is manipulating a directory called `lisp-utils', the command to rebuild the auto-autoloads.el file is:

     xemacs -vanilla -batch \
       -eval \("setq autoload-package-name \"lisp-utils\""\) \
       -f batch-update-directory lisp-utils

The command to rebuild the custom-load.el file is:

     xemacs -vanilla -batch -f Custom-make-dependencies lisp-utils

To byte-compile both of these files the command is:

     xemacs -vanilla -batch -f batch-byte-compile \
     	lisp-utils/auto-autoloads.el lisp-utils/custom-load.el

Of course, being a beta tester, you'd be aware that it is much easier to manage your XEmacs packages with PUI.

Building XEmacs and XEmacs packages from scratch
================================================

To build everything completely from scratch isn't hard, just time consuming.

Step 1 - grab the sources (core and packages)
---------------------------------------------

     $ cvs -d :pserver:cvs@cvs.xemacs.org:/pack/xemacscvs login
      [password: "cvs" (sans quotes)]

     $ cvs -d :pserver:cvs@cvs.xemacs.org:/pack/xemacscvs co -d xemacs-21.5 xemacs

     $ cvs -d :pserver:cvs@cvs.xemacs.org:/pack/xemacscvs co packages

Step 2 - build XEmacs
---------------------

     $ cd xemacs-21.5
     $ ./configure [options...]
     $ make > ./beta.err 2>&1
     $ make check > ./xemacs-make-check.err 2>&1

And optionally:

     $ make install > ./xemacs-make-install.err 2>&1

Step 3 - build and install the packages
---------------------------------------

     $ cd packages
     $ cp Local.rules.template Local.rules

Then edit Local.rules to suit your needs/environment (see Local.rules file (XEmacs User's Manual)) for details about this file.

And then:

     $ make install

Improving XEmacs
****************

Creating patches for submission
===============================

All patches to XEmacs that are seriously proposed for inclusion (eg, bug fixes) should be mailed to mailto:xemacs-patches@xemacs.org.  Each patch will be reviewed by the patches review board, and will be acknowledged and added to the distribution, or rejected with an explanation.  Progress of the patch is tracked on the XEmacs Patches mailing list, which is open subscription.  (If a patch is simply intended to facilitate discussion, "I mean something that works like this but this is really rough", a Cc to XEmacs Patches is optional, but doesn't hurt.)

Patches to XEmacs Lisp packages should be sent to the maintainer of the package.  If the maintainer is listed as `XEmacs Development Team' patches should be sent to mailto:xemacs-patches@xemacs.org.

Emailed patches should preferably be sent in MIME format and quoted printable encoding (if necessary).

The simplest way to create well-formed patches is to use CVS and Didier Verna's Patcher library (available as patcher.el in the xemacs-devel package).  Patcher is new and requires some setup, but most of the core developers are now using it for their own patches. Patcher also can be configured to create patches for several projects, and recognize the project from the directory it is invoked in.  This makes it a useful general tool (as long as XEmacs-style patches are accepted at your other projects, which is likely since they conform to the GNU standards).

When making patches by hand, please use the `-u' option, or if your diff doesn't support it, `-c'.  Using ordinary (context-free) diffs are notoriously prone to error, since line numbers tend to change when others make changes to the same source file.

An example of the `diff' usage:

     $ diff -u OLDFILE NEWFILE

-or-

     $ diff -c OLDFILE NEWFILE

Also, it is helpful if you create the patch in the top level of the XEmacs source directory:

     $ cp -p lwlib/xlwmenu.c lwlib/xlwmenu.c.orig
       hack, hack, hack....
     $ diff -u lwlib/xlwmenu.c.orig lwlib/xlwmenu.c

Also note that if you cut & paste from an xterm to an XEmacs mail buffer you will probably lose due to tab expansion.  The best thing to do is to use an XEmacs shell buffer to run the diff commands, or ... M-x cd to the appropriate directory, and issue the command C-u M-! from within XEmacs.

Patches should be as single-minded as possible.  Mammoth patches can be very difficult to place into the right slot.  They are much easier to deal with when broken down into functional or conceptual chunks. The patches submitted by Kyle Jones and Hrvoje Niksic are stellar examples of how to "Do The Right Thing".

Each patch should be accompanied by an update to the appropriate ChangeLog file.  Guidelines for writing ChangeLog entries is governed by the GNU coding standards.  Please see http://www.gnu.org/prep/standards_toc.html   [Change Logs section] for details.

Do not submit context diffs (either -c or -u) of ChangeLogs.  Because of the "stack" nature of ChangeLogs (new entries are always pushed on the top), context diffs will fail to apply more often than they succeed.  Simply cutting and pasting the entry from an Emacs buffer to the mail buffer (beware of tab expansion!) is probably easiest.  The Patcher library also will set up your ChangeLogs for you, and copy them to the mail.  Context-less unified diffs (-U 0) are also acceptable.

Patch discussion etiquette
--------------------------

If you intend a patch for _application_ to the sources as is, _always_ post it to xemacs-patches, even if there are minor points you would like to have discussed by others.  Not doing so will resulting in patches getting "lost".  If you expect that the patch will not be acceptable, but are using it to stimulate discussion, then don't post to xemacs-patches.  Intermediate cases are up to your judgment; unless you're sure you'll follow up with a "real" patch, better to err on the side of posting to xemacs-patches.

Discussion of the _content_ of the patch (ie responses to reviewer comments beyond "that's right, ok, I'll do it your way") should _always_ be posted to xemacs-beta or to xemacs-design.  If you're not sure which is more appropriate, send it to xemacs-beta.  That is the most widely read channel.

If discussion results in a bright idea and you come up with a new patch, normally you should post it to both mailing lists.  The people discussing on XEmacs Beta will want to know the outcome of the thread, and you need to submit to XEmacs Patches as the "list of record."

If the old patch has been applied to CVS, then just submit the new one as usual.  If it has not been applied, then it is best to submit a new patch against CVS.  If possible do this as a reply to the original patch post, or something following it in the thread.  (The point is to get the original patch post's Message-ID in your References header.) In this case, also use the keyword SUPERSEDES in the Subject header to indicate that the old patch is no longer valid, and that this one replaces it.

These rules will result in a fair number of cross posts, but we don't yet have a better way to handle that.

Note: Developers should never post to xemacs-patches unless there is a patch in the post.  We plan to enforce this with an automatic filter.

The exceptions are administrative.  If you have commit authorization, then post a short COMMIT notice to xemacs-patches when you commit to CVS.  Members of the Review Board will also post short notices of administrative action (APPROVE, VETO, QUERY, etc) to xemacs-patches.

Large contributions
===================

Perhaps you have a whole new mode, or a major synchronization with upstream for a neglected package, or a synchronization with GNU Emacs you would like to contribute.  We welcome such contributions, but they are likely to be relatively controversial, generate more comments and requests for revision, and take longer to integrate.  Please be patient with the process.

Updates to existing packages
----------------------------

If a package has gotten a bit out of date, or even started to bitrot, we welcome patches to synchronize it with upstream/GNU Emacs versions. Most packages end up varying somewhat from their GNU origins.  See "Syncing with GNU Emacs" for hints.  Note that if you do a reasonably large amount of syncing with GNU Emacs, you should log this in the file itself as well as in the ChangeLog.

If the package is important to you, please consider becoming the maintainer.  (See "New packages", below.)

New packages
------------

If you have a new mode or other large addition that does not require changes to the core, please consider submitting it as a package, and becoming the maintainer.  You get direct commit privileges to the repository for your package, "approval" privileges for your own patches as well as third party patches to your package, and some degree of veto power over patches you don't like.  In return, you are expected to maintain friendly liaison with the upstream developer (if you aren't the upstream developer), keep watch on the XEmacs Patches list for relevant patches, and be available by email to other developers for discussion of changes that impact your package.  It's also a pretty standard route to the "core" development group, where we have plenty of extra work waiting for volunteers.

You don't have to become the maintainer, but it virtually ensures rapid acceptance of the package.

For help in creating new packages, see the (rather sparse) discussions in the XEmacs User's Guide and the Lisp Reference Manual.  The participants in the XEmacs Beta mailing list mailto:xemacs-beta@xemacs.org and the XEmacs Package Release Engineer are the most likely sources of advice.  See jobs.html (http://www.xemacs.org/Develop/jobs.html#package) for current information about package release engineers.

Syncing with GNU Emacs
----------------------

Syncing with GNU Emacs is an important activity.  Although each version has its advantages and areas of concentration, it is very desirable that common functionality share specifications and APIs. When porting GNU code to XEmacs, the following points should be given special attention:

  * Recent GNU Emacsen cannot be built without Mule, but XEmacs can. Make sure that changes that depend on the presence of Mule are appropriately conditionalized, with #ifdef MULE in C code and with (featurep 'mule) in Lisp.

  * GNU Emacs nomenclature often differs from that of XEmacs. Sometimes syncing the names is desirable, other times not.

  * GNU Emacs functionality often differs from that of XEmacs. Syncing functionality is often controversial.

It is important that you let other developers know that synchronization has taken place, to what degree, and when.  For this purpose, we use comments of the form

     /* Synched up with: GNU 21.3 by Stephen Turnbull */

in the source file itself, as the last element of the prefatory material (copyright notice and commentary).  Obviously the comment marker needs to be changed to leading semicolons for Lisp, but otherwise the format is the same.  (Older sync comments may have ``FSF'' in place of ``GNU''.  They're equally accurate in our opinion, but Richard Stallman and other GNU developers consider the term ``FSF Emacs'' ``insulting''.  Please use ``GNU'' in new sync comments.)

Of course you should note syncing as the purpose in the ChangeLog, too.  But entries get buried deep in the ChangeLog file, and may even get moved to a separate ChangeLog.OLD file for rarely synched files.

Rather than dates we use the version of GNU Emacs to sync to.  If the synchronization is partial, add a new comment describing what has actually been synched, leaving the description of the last full sync in place.  At each full sync, remove all previous synchronization comments.

This applies to Lisp that we have broken out into packages, but remains in the GNU Emacs core, as well to core Lisp in XEmacs.