In the first semester of the Master of Libre Software that I am attending, we had a course called Case Studies I in which the teachers introduced us several interesting tools for the own master homework. It was an opportunity to link concepts explained in other subjects with the practical knowledge of some applications. In this post I will talk about some of those applications and the free licenses that these tools use: Gobby, Git, Moodle, TeX and LaTeX.
Gobby is an editor which allows to edit text documents and source files collaboratively over a network. Changes to the documents are synchronised instantly to the other clients. I am using the version 0.5 of Gobby and its legal information is this:
Copyright © 2008, 2009 Armin Burgmeier
Armin Burgmeier <firstname.lastname@example.org>
Philipp Kern <email@example.com>
Benjamin Herr <firstname.lastname@example.org>
Ben Levitt <email@example.com>
Gabríel A. Pétursson <firstname.lastname@example.org>
British English: Gabríel A. Pétursson <email@example.com>
Benjamin Herr <firstname.lastname@example.org>
Thomas Glatt <email@example.com>
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.
Git, the fast Control Version System
I already talk about Git in several posts.
Originally written by Linus Torvalds for supporting Linux development, Git is distributed under GPLv2 license.
Moodle is a software package for producing Internet-based courses and web sites.
The overall Moodle software package is Copyright © 1999 onwards, Martin Dougiamas with portions contributed/copyrighted by many others and all of it is provided under the terms of the GPL. 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.
TeX is a typesetting system designed and mostly written by Donald E. Knuth, with two objectives: to allow anybody to produce high-quality books using a reasonable amount of effort, and to provide a system that would give exactly the same results on all computers, now and in the future.
Here I transcript a paragraph from TeX Wikipedia entry, about the license. It is very interesting:
“Donald Knuth has indicated several times that the source code of TeX has been placed into the “public domain,” and he strongly encourages modifications or experimentations with this source code. However, since the code is still copyrighted, it is technically free/open-source software but is not in the public domain in the legal sense. In particular, since Knuth highly values the reproducibility of the output of all versions of TeX, any changed version must not be called TeX, TeX, or anything confusingly similar. To enforce this rule, any implementation of the system must pass a test suite called the TRIP test before being allowed to be called TeX. The question of license is somewhat confused by the statements included at the beginning of the TeX source code, which indicate that “all rights are reserved. Copying of this file is authorized only if (…) you make absolutely no changes to your copy”. However, this restriction should be interpreted as a prohibition to change the source code as long as the file is called tex.web. This interpretation is confirmed later in the source code when the TRIP test is mentioned (“If this program is changed, the resulting system should not be called ‘TeX'”)”.
LaTeX is a document markup language and document preparation system for the TeX typesetting system. It was originally written in the early 1980s by Leslie Lamport. The current version is LaTeX2e.
It is a set of macros from TeX primitives, which incorporates document styles for books, letters, slides, etc.
LaTeX is free software distributed under the terms of the LaTeX Project Public License (LPPL), OSI-compliant. It is a permissive license.
The LPPL Wikipedia entry also throws interesting legal aspects:
“The LPPL grew from Donald Knuth‘s original license for TeX, which states that the source code for TeX may be used for any purpose but a system built with it can only be called ‘TeX’ if it strictly conforms to his canonical program. The incentive for this proviso was to ensure that documents written for TeX will be readable for the foreseeable future […]
The most unusual part of the LPPL — and equally the most controversial — used to be the ‘filename clause’: You must not distribute the modified file with the filename of the original file. This feature made some people deny that the LPPL is a free software license. In particular the Debian Linux community considered excluding LaTeX from its core distribution because of this.
However, version 1.3 of the LPPL has weakened this restriction. Now it is only necessary that modified components identify themselves “clearly and unambiguously” as modified versions, both in the source and also when called in some sort of interactive mode. A name change of the work is still recommended, however. This appeased the Debian community.”