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diff --git a/docs/librejs.texi b/docs/librejs.texi new file mode 100644 index 0000000..83f2403 --- /dev/null +++ b/docs/librejs.texi @@ -0,0 +1,768 @@ +\input texinfo @c -*-texinfo-*- +@c %**start of header +@setfilename librejs.info +@include version.texi +@settitle GNU LibreJS @value{VERSION} + +@copying +This manual is for GNU LibreJS (version @value{VERSION}, @value{UPDATED}), +a GNU IceCat extension to detect and block nonfree nontrivial +JavaScript on webpages. + +Copyright @copyright{} 2011 2012 2014 2015 Loic J. Duros, 2022 Yuchen Pei + +@quotation +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 section entitled +``GNU Free Documentation License''. +@end quotation +@end copying + +@dircategory GNUzilla +@direntry +* LibreJS: (librejs). Detect nonfree nontrivial in GNU Icecat +@end direntry + +@titlepage +@title GNU LibreJS +@subtitle for version @value{VERSION}, @value{UPDATED} +@author Loic J. Duros (@email{librejs@@lduros.net}) +@author Yuchen Pei (@email{ycp@@gnu.org}) +@page +@vskip 0pt plus 1filll +@insertcopying +@end titlepage + + +@contents + + +@node Top +@top LibreJS +This manual is for GNU LibreJS (version @value{VERSION}, @value{UPDATED}). + +@menu +* Overview:: General purpose and information. +* Disclaimer:: Emphasize what LibreJS does and does not. +* Installation:: Installing LibreJS from source. +* How to Use:: How to use LibreJS in IceCat. +* JavaScript Detection:: How LibreJS detects nontrivial Javascript. +* Free Licenses Detection:: List of licenses detected by LibreJS. +* Setting Your JavaScript Free:: Information for website owners/maintainers. +* LibreJS Development Notes:: Documentation about the development of + LibreJS itself. +* Installation Requirements:: Requirements to build and install LibreJS. +* LibreJS Internals:: How LibreJS works under the hood. +* GNU Free Documentation License:: Copying and sharing this documentation. + + + + + + + + +@end menu + +@node Overview +@chapter Overview + +@cindex overview +GNU LibreJS ---an add-on for GNU IceCat and Mozilla Firefox--- detects +and blocks nonfree nontrivial JavaScript while allowing its execution on +pages containing code that is either trivial and/or free. + +Many websites run nontrivial JavaScript on your computer. Some use it +for complex tasks; many use it gratuitously for minor jobs that could be +done easily with plain HTML. Sometimes this JavaScript code is +malicious. Either way, the JavaScript code is often nonfree. For +explanation of the issue, see "The JavaScript +Trap"(@url{http://www.gnu.org/philosophy/javascript-trap.html}). + +If you care about freedom in your computing, and don't wish to let all +and sundry make you run nonfree programs, now you can prevent it by +using LibreJS. + + +@node Disclaimer +@chapter Disclaimer + +@cindex disclaimer + +@itemize @bullet +@item +LibreJS is not a security tool. Its goal is to detect nonfree nontrivial +JavaScript, and it currently does not detect whether free or trivial +code is malicious or not. Other free Mozilla extensions and add-ons may +be available for this purpose. + +@item +LibreJS is always a work in progress. If you find a bug, please report +it to @email{bug-librejs@@gnu.org}. + +@end itemize + +@node Installation +@chapter Installation +@cindex Installation + +You can install LibreJS directly using a generated @file{librejs.xpi} +file, or by building it from source (@xref{LibreJS Development Notes}). + +You can also download it from +@url{https://www.gnu.org/software/librejs/} or +@url{https://addons.mozilla.org/addon/librejs/}, but due to Mozilla's +review process the download isn't always up to date. + +@node How to Use +@chapter How to Use + +@section LibreJS in action + +After installing the add-on, you will see the LibreJS widget in the +add-on bar at the top right of the browser window. After loading a +page, left-click on the widget to view the deactivated JavaScript code +from the page (both on page and external) and, if applicable, the +scripts that were accepted. + +@section Script Blacklist/whitelist + +Scripts may be blacklisted or whitelisted through the pop-up menu box. + +Whitelisted scripts will always be accepted and blacklisted scripts +will always get rejected. + +It is important to note that this feature recognizes which scripts are +blacklisted and whitelisted based on hash. This means that even a slight +difference in a script's code will cause it to be recognized as a +separate script. + +Sometimes, JavaScript will be dynamically generated so that it is +different every time a website is loaded. These types of scripts cannot +be whitelisted or blacklisted since they cannot be recognized. + +LibreJS has a default whitelist of scripts that are known to be free but +may not declare their license in a format that LibreJS can understand. + +@section Complaint Feature + +It is very important to complain when a site has nonfree JavaScript +code, especially if it won't work without that code. LibreJS makes it +easy to complain by heuristically finding where to send the complaint. + +When nonfree/nontrivial code is detected in a page, LibreJS attempts to +find a relevant contact link or email for the website you are +visiting. In order to do so, it will attempt to visit a few links from +the current page (for instance, a link labeled ``contact'' on the same +domain as the current page, @dots{}) + +LibreJS detects contact pages, email addresses that are likely to be +owned by the maintainer of the site, Twitter and identi.ca links, and +phone numbers. + +When you complain to the website for their nonfree nontrivial +JavaScript, provide them with the link to the JavaScript Trap essay so +that they can get more information on what the issue is and how they can +solve it on their own site. + +LibreJS includes a default subject line and body for the complaint email, +with a link to the JavaScript Trap essay. This can be configured in the +LibreJS add-on preferences in your web browser. + +@section Options + +@table @dfn + +You can manage LibreJS's preferences either from the extension's entry in your +browser's Add-ons Manager page (@code{about:addons}) or by clicking the LibreJS +toolbar icon and then the "Settings..." button on the top right of the popup. +This will open a panel containing a whitelist/blacklist manager and a section +to configure your complaints messages to site owners. + +@item Whitelist/Blacklist + +LibreJS lets you whitelist or blacklist domain names and subdomains, to bypass +the regular JavaScript checks. This might be useful, for example, if you are +running your own code in a local web server, or if you don't want to waste +computing resources on script origins you already know you can't trust. librejs +provides a lists manager UI to handle both the lists on the top of its Options +panel. + +@item Complaint email subject +Configure the default subject used in complaint emails. + +@item Complaint email body +Configure the default body used in complaint emails. +@end table + +@node JavaScript Detection +@chapter JavaScript Detection +@cindex javascript + +LibreJS considers a very strict subset of JavaScript to be acceptable for use +in non-free scripts. This is meant to maximimize compatibility with websites +that haven't tried to be LibreJS compatible. + +We consider modification of the document non-trivial. There isn't +much that javascript could do that we would consider trivial, for +anything else a free software license would be required. + +The criterion is as follows: + + For each function definition: +@itemize @bullet + @item + It must call only primitives. + @item + The number of conditionals and loops must be at most 3. + @item + It does not declare an array more than 50 elements long. + @item + It must not call itself +@end itemize + +For the rest of the script, outside of function definitions: +@itemize @bullet + @item + It must call only primitives and functions defined above in the page. + @item + The number of conditionals and loops must be at most 3. +@end itemize + +"function" means anything executable that gets a name, including methods. + +Allowed primitives exclude: + @itemize @bullet + @item + eval() + @item + ajax + @item + calling methods with the square bracket notation + @item + altering the dom + @item + most other items found as methods of the `.window` object. + @end itemize + + +@node Free Licenses Detection +@chapter Free Licenses Detection +@cindex freelicenses + +The machine readable format for license declarations that LibreJS uses +has changed in the most recent version. This was necessary in order to +not break the asynchronous JS loading model that browsers use. Scripts +are now evaluated independent of eachother and strictly as they +arrive. + +@node Setting Your JavaScript Free +@chapter Setting Your JavaScript Free + +The first step is releasing your JavaScript under a free license. If +you are already using a free library, or you're not using any +third-party libraries, it might only take a few minutes. + +On your website, take a look at your HTML source. You can identify +distinct pieces of JavaScript that might be free and some other that are +nonfree. + +This might be the case with an analytics tracker, social media +widgets, and code that runs ads. Removing these pieces of code from your +site is required to have the rest accepted as free. There are +often alternatives to nonfree libraries or to third-party services: + +@itemize @bullet + +@item +If you have used nonfree third-party code as the base to write your own +code, try to find a free alternative. + +@item +If you're using a third-party service such as an analytics service, +replace it with a free alternative like Piwik. + +@item +If you can't find free JavaScript that has already been developed, +write it yourself! Who knows, your own solution might be the start of +a brilliant project! +@end itemize + + +@section License tags + +LibreJS will allow non-trivial scripts to run as long as they use a +free license. + +In order for the license of a script to be recognized by LibreJS, it +must be declared using a machine-readable license format. + +This format is the same for both remote in-line scripts. + +"// @@license [magnet link] [identifier]" +[Script here] +"// @@license-end" + +"Identifier" is a name of a license from the following list and the +magnet link in the @code{canonicalUrl} field is that license's exact +corresponding magnet link. + +@verbatim +{ + 'AGPL-3.0': { + licenseName: 'GNU AFFERO GENERAL PUBLIC LICENSE version 3', + identifier: 'AGPL-3.0', + canonicalUrl: [ + 'http://www.gnu.org/licenses/agpl-3.0.html', + 'magnet:?xt=urn:btih:0b31508aeb0634b347b8270c7bee4d411b5d4109&dn=agpl-3.0.txt' + ], + + }, + + 'Apache-2.0': { + licenseName: 'Apache License, Version 2.0', + identifier: 'Apache-2.0', + canonicalUrl: [ + 'http://www.apache.org/licenses/LICENSE-2.0', + 'magnet:?xt=urn:btih:8e4f440f4c65981c5bf93c76d35135ba5064d8b7&dn=apache-2.0.txt' + ], + }, + + 'Artistic-2.0': { + licenseName: "Artistic License 2.0", + identifier: 'Artistic-2.0', + canonicalUrl: [ + "http://www.perlfoundation.org/artistic_license_2_0", + "magnet:?xt=urn:btih:54fd2283f9dbdf29466d2df1a98bf8f65cafe314&dn=artistic-2.0.txt" + ], + }, + + 'BSD-2-Clause': { + licenseName: "BSD 2-Clause License", + identifier: 'BSD-2-Clause', + canonicalUrl: [ + 'http://www.freebsd.org/copyright/freebsd-license.html', + 'magnet:?xt=urn:btih:87f119ba0b429ba17a44b4bffcab33165ebdacc0&dn=freebsd.txt' + ], + }, + + 'BSD-3-Clause': { + licenseName: "BSD 3-Clause License", + identifier: 'BSD-3-Clause', + canonicalUrl: [ + 'http://opensource.org/licenses/BSD-3-Clause', + 'magnet:?xt=urn:btih:c80d50af7d3db9be66a4d0a86db0286e4fd33292&dn=bsd-3-clause.txt' + ], + }, + + 'BSL-1.0': { + licenseName: 'Boost Software License 1.0', + identifier: 'BSL-1.0', + canonicalUrl: [ + 'http://www.boost.org/LICENSE_1_0.txt', + 'magnet:?xt=urn:btih:89a97c535628232f2f3888c2b7b8ffd4c078cec0&dn=Boost-1.0.txt' + ], + }, + + 'CC-BY-1.0': { + licenseName: 'Creative Commons Attribution 1.0 Generic', + identifier: 'CC-BY-1.0', + canonicalUrl: ['https://creativecommons.org/licenses/by/1.0/'], + }, + + 'CC-BY-2.0': { + licenseName: 'Creative Commons Attribution 2.0 Generic', + identifier: 'CC-BY-2.0', + canonicalUrl: ['https://creativecommons.org/licenses/by/2.0/'], + }, + + 'CC-BY-2.5': { + licenseName: 'Creative Commons Attribution 2.5 Generic', + identifier: 'CC-BY-2.5', + canonicalUrl: ['https://creativecommons.org/licenses/by/2.5/'], + }, + + 'CC-BY-3.0': { + licenseName: 'Creative Commons Attribution 3.0 Unported', + identifier: 'CC-BY-3.0', + canonicalUrl: ['https://creativecommons.org/licenses/by/3.0/'], + }, + + 'CC-BY-4.0': { + licenseName: 'Creative Commons Attribution 4.0 International', + identifier: 'CC-BY-4.0', + canonicalUrl: ['https://creativecommons.org/licenses/by/4.0/'], + }, + + 'CC-BY-SA-1.0': { + licenseName: 'Creative Commons Attribution-ShareAlike 1.0 Generic', + identifier: 'CC-BY-SA-1.0', + canonicalUrl: ['https://creativecommons.org/licenses/by-sa/1.0/'], + }, + + 'CC-BY-SA-2.0': { + licenseName: 'Creative Commons Attribution-ShareAlike 2.0 Generic', + identifier: 'CC-BY-SA-2.0', + canonicalUrl: ['https://creativecommons.org/licenses/by-sa/2.0/'], + }, + + 'CC-BY-SA-2.5': { + licenseName: 'Creative Commons Attribution-ShareAlike 2.5 Generic', + identifier: 'CC-BY-SA-2.5', + canonicalUrl: ['https://creativecommons.org/licenses/by-sa/2.5/'], + }, + + 'CC-BY-SA-3.0': { + licenseName: 'Creative Commons Attribution-ShareAlike 3.0 Unported', + identifier: 'CC-BY-SA-3.0', + canonicalUrl: ['https://creativecommons.org/licenses/by-sa/3.0/'], + }, + + 'CC-BY-SA-4.0': { + licenseName: 'Creative Commons Attribution-ShareAlike 4.0 International', + identifier: 'CC-BY-SA-4.0', + canonicalUrl: ['https://creativecommons.org/licenses/by-sa/4.0/'], + }, + + 'CC0-1.0': { + licenseName: 'Creative Commons CC0 1.0 Universal', + identifier: 'CC0-1.0', + canonicalUrl: [ + 'http://creativecommons.org/publicdomain/zero/1.0/legalcode', + 'magnet:?xt=urn:btih:90dc5c0be029de84e523b9b3922520e79e0e6f08&dn=cc0.txt' + ], + }, + + 'CPAL-1.0': { + licenseName: 'Common Public Attribution License Version 1.0 (CPAL)', + identifier: 'CPAL-1.0', + canonicalUrl: [ + 'http://opensource.org/licenses/cpal_1.0', + 'magnet:?xt=urn:btih:84143bc45939fc8fa42921d619a95462c2031c5c&dn=cpal-1.0.txt' + ], + }, + + 'EPL-1.0': { + licenseName: "Eclipse Public License Version 1.0", + identifier: "EPL-1.0", + canonicalUrl: [ + "http://www.eclipse.org/legal/epl-v10.html", + "magnet:?xt=urn:btih:4c6a2ad0018cd461e9b0fc44e1b340d2c1828b22&dn=epl-1.0.txt" + ], + }, + + 'Expat': { + licenseName: 'Expat License (sometimes called MIT Licensed)', + identifier: 'Expat', + canonicalUrl: [ + 'http://www.jclark.com/xml/copying.txt', + 'magnet:?xt=urn:btih:d3d9a9a6595521f9666a5e94cc830dab83b65699&dn=expat.txt' + ], + }, + + 'FreeBSD': { + licenseName: "FreeBSD License", + identifier: 'FreeBSD', + canonicalUrl: [ + 'http://www.freebsd.org/copyright/freebsd-license.html', + 'magnet:?xt=urn:btih:87f119ba0b429ba17a44b4bffcab33165ebdacc0&dn=freebsd.txt' + ], + }, + + 'GNU-All-Permissive': { + licenseName: 'GNU All-Permissive License', + identifier: 'GNU-All-Permissive', + canonicalUrl: [], + }, + + 'GPL-2.0': { + licenseName: 'GNU General Public License (GPL) version 2', + identifier: 'GPL-2.0', + canonicalUrl: [ + 'http://www.gnu.org/licenses/gpl-2.0.html', + 'magnet:?xt=urn:btih:cf05388f2679ee054f2beb29a391d25f4e673ac3&dn=gpl-2.0.txt' + ], + }, + + 'GPL-3.0': { + licenseName: 'GNU General Public License (GPL) version 3', + identifier: 'GPL-3.0', + canonicalUrl: [ + 'http://www.gnu.org/licenses/gpl-3.0.html', + 'magnet:?xt=urn:btih:1f739d935676111cfff4b4693e3816e664797050&dn=gpl-3.0.txt' + ], + }, + + 'ISC': { + licenseName: "The ISC License", + identifier: 'ISC', + canonicalUrl: [ + 'https://www.isc.org/downloads/software-support-policy/isc-license/', + 'magnet:?xt=urn:btih:b8999bbaf509c08d127678643c515b9ab0836bae&dn=ISC.txt' + ], + }, + + 'jQueryTools': { + licenseName: "jQuery Tools", + identifier: 'jQueryTools', + canonicalUrl: [], + }, + + 'LGPL-2.1': { + licenseName: 'GNU Lesser General Public License, version 2.1', + identifier: 'LGPL-2.1', + canonicalUrl: [ + 'http://www.gnu.org/licenses/lgpl-2.1.html', + 'magnet:?xt=urn:btih:5de60da917303dbfad4f93fb1b985ced5a89eac2&dn=lgpl-2.1.txt' + ], + }, + + 'LGPL-3.0': { + licenseName: 'GNU Lesser General Public License, version 3', + identifier: 'LGPL-3.0', + canonicalUrl: [ + 'http://www.gnu.org/licenses/lgpl-3.0.html', + 'magnet:?xt=urn:btih:0ef1b8170b3b615170ff270def6427c317705f85&dn=lgpl-3.0.txt' + ], + }, + + 'MPL-2.0': { + licenseName: 'Mozilla Public License Version 2.0', + identifier: 'MPL-2.0', + canonicalUrl: [ + 'http://www.mozilla.org/MPL/2.0', + 'magnet:?xt=urn:btih:3877d6d54b3accd4bc32f8a48bf32ebc0901502a&dn=mpl-2.0.txt' + ], + }, + + 'PublicDomain': { + licenseName: 'Public Domain', + identifier: 'PublicDomain', + canonicalUrl: [ + 'magnet:?xt=urn:btih:e95b018ef3580986a04669f1b5879592219e2a7a&dn=public-domain.txt' + ], + }, + + + 'Unlicense': { + licenseName: 'Unlicense', + identifier: 'Unlicense', + canonicalUrl: [ + 'http://unlicense.org/UNLICENSE', + 'magnet:?xt=urn:btih:5ac446d35272cc2e4e85e4325b146d0b7ca8f50c&dn=unlicense.txt' + ], + }, + + 'UPL': { + licenseName: 'Universal Permissive License', + identifier: 'UPL-1.0', + canonicalUrl: [ + 'https://oss.oracle.com/licenses/upl/', + 'magnet:?xt=urn:btih:478974f4d41c3fa84c4befba25f283527fad107d&dn=upl-1.0.txt' + ], + }, + + 'WTFPL': { + licenseName: 'Do What The F*ck You Want To Public License (WTFPL)', + identifier: 'WTFPL', + canonicalUrl: [ + 'http://www.wtfpl.net/txt/copying/', + 'magnet:?xt=urn:btih:723febf9f6185544f57f0660a41489c7d6b4931b&dn=wtfpl.txt' + ], + }, + + 'X11': { + licenseName: 'X11 License', + identifier: 'X11', + canonicalUrl: [ + 'magnet:?xt=urn:btih:5305d91886084f776adcf57509a648432709a7c7&dn=x11.txt' + ], + }, + + 'XFree86-1.1': { + licenseName: "XFree86 1.1 License", + identifier: 'XFree86-1.1', + canonicalUrl: [ + 'http://www.xfree86.org/3.3.6/COPYRIGHT2.html#3', + 'http://www.xfree86.org/current/LICENSE4.html', + 'magnet:?xt=urn:btih:12f2ec9e8de2a3b0002a33d518d6010cc8ab2ae9&dn=xfree86.txt' + ], + }, +} +@end verbatim + +@section Undetected Free Licenses + +If you are using a free license that isn't detected by LibreJS and isn't +listed in the previous section, please send a message to +@email{bug-librejs@@gnu.org} regarding this license, where code released under +this license can be found, and where to find the license text and +information. + +Many free licenses are listed in this page: +@url{http://www.gnu.org/licenses/license-list.html} + +@section Known limitations + +Service workers may cause false positives and false negatives, and +there are multiple ways to disable them. The cleanest way is by +setting @code{dom.serviceWorkers.enabled} to @code{false} in the +@code{about:config} page of your browser. + +@node LibreJS Development Notes +@chapter LibreJS Development Notes + +@section Dependencies + +LibreJS @value{VERSION} depends on a number of Node.js-based libraries that +can be installed using the @code{npm} utility: + +@verbatim + $ npm install acorn-loose jassha browserify + $ export PATH=$PATH:./node_modules/.bin +@end verbatim + +@section Building + +To build the extension run: +@verbatim + $ browserify main_background.js -o bundle.js +@end verbatim + +To build the extension plus create a .xpi package run: +@verbatim + $ ./build.sh +@end verbatim + +To build the extension including the automated test suite (see TEST below) run: +@verbatim + $ ./build.sh -t +@end verbatim +or +@verbatim + $ ./build.sh --test +@end verbatim + +Note: this @file{build.sh} script relies on no new source files being created. + +@section Debugging + +To debug LibreJS, visit the special URL @code{about:debugging}. Click +on `Enable add-on debugging` then `Load Temporary Add-on`. Navigate +to LibreJS's unpacked source directory and select @file{manifest.json}. + +Lines 39 and 40 in @file{main_background.js} assign two variables +controlling the verbosity of @code{dbg_print()} statements. Make sure +these are set to false before building a release. + +@section Testing + +An automated test suite runs automatically in its own tab whenever the +extension is loaded as a "Temporary add-on" from +@code{about:debugging}. Otherwise (if included in the xpi) it can be +launched from the UI by clicking the "Automated self test..." button. + +@section Headless testing + +To launch the test suite from the command line, ensure the xpi package +has been built with automated test suite. Then install +selenium-webdriver and geckodriver, and ensure the latter is in $PATH: +@verbatim + $ npm install selenium-webdriver geckodriver + $ export PATH=$PATH:./node_modules/.bin +@end verbatim + +Now you can invoke the test with +@verbatim + $ node ./test.js +@end verbatim + +which will print out a summary of test results. + +Optionally you can also test with a chosen seed +@verbatim + $ node ./test.js 12345 +@end verbatim + +@section Headless compliance check +To check whether a webpage is LibreJS-compliant from the command line, +ensure that the xpi package has been built WITHOUT the automated test +suite. Then install selenium-webdriver and geckodriver, and ensure the +latter is in $PATH: +@verbatim + $ npm install selenium-webdriver + $ npm install geckodriver + $ export PATH=$PATH:./node_modules/.bin +@end verbatim + +Now you can check a webpage for compliance with +@verbatim + $ node ./compliance.js <url> +@end verbatim + +It will open the url in a headless browser, save a screenshot, and +output the compliance check result. + +For example, to check the compliance of the FSF homepage, do +@verbatim + $ node ./compliance.js https://fsf.org +@end verbatim + +@section Adding new whitelisted libraries + +The script index.js in @file{./hash_script} generates the default +whitelist. Run it with the following command: + +@command{node index.js > output} + +Then, just copy the contents of the file "output" to the appropriate +place in main_background.js. + +@section Releasing a new version + +Update the version number in manifest.json. + +Make sure debug statements are set to false on lines 39/40 in +@file{main_background.js}. + +Then run the build script @file{build.sh}. + +@node Installation Requirements +@appendix Installation Requirements + + +@appendixsec Mozilla Browser + +You will need one of the many flavors of the Mozilla browser to use +LibreJS. It can be installed on the following: + +GNU IceCat, Mozilla Firefox, Trisquel Abrowser, Debian Iceweasel. + +LibreJS works on these browsers starting from version 60. We recommend +that you use the latest version of your Mozilla browser. LibreJS has +been tested on a GNU/Linux distribution, but it is compatible any +operating system as long as you're using a compatible Mozilla browser. + +@node LibreJS Internals +@appendix LibreJS Internals + +LibreJS intercepts HTTP responses and rewrites their contents after +analyzing JavaScript within them. It does not remove script nodes and +attributes from the page, but instead ``deactivates'' them by replacing +their content with a commented notice. + +LibreJS detects the most common cases using the HTTP response method +described above, but in less common edge cases, or when running code +locally, LibreJS cannot detect JavaScript during the response stage. + + +@node GNU Free Documentation License +@appendix GNU Free Documentation License + +@include fdl.texi + + +@bye |