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The GPL is viral. How does this apply to the LaTeX eco system if one uses a package licensed under the GPL2++?

  1. If I use it in a document, must the document also be licensed under the GPL?
  2. If I use it in a package, must that package also be licensed under the GPL?
  3. If I use it in a document class, must the document class also be licensed under the GPL?
  4. If I create a program that creates LaTeX code which uses 1, 2 or 3 - must that program also be licensed under the GPL?
David Carlisle
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Martin Schröder
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  • As long as you don't reuse any code from the package and don't distribute it yourself, I don't think your own code is affected. – bodo Aug 27 '12 at 13:41
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    @Martin I assume that the background to the question here is that TeX code is used 'raw' by TeX (ultimately \input), with no compilation. There's a contrast to a compiled GPL program, where I can use it's 'defined interfaces' without accessing the code and without needing to license under the GPL. My worry from the POV of TeX-sx is that this is a legal question, which is not the area of expertise of the majority of us (and indeed the network as a whole avoids legal questions for I think obvious reasons). – Joseph Wright Aug 27 '12 at 13:48
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    @canaaerus: Think of the LaTeX package as a library and all the uses cases are c programs (or libraries) calling that library. Then everything must be licensed as GPL. This is why the LGPL exists... – Martin Schröder Aug 27 '12 at 13:49
  • @JosephWright: You are right about the background. But see my comment to @canaaerus. I'd be happy if this question would be migrated to a more fitting sx, but we have the licensing tag... – Martin Schröder Aug 27 '12 at 13:51
  • @MartinSchröder: I don't think that can be correct. Any linux application makes system calls, thus using the linux kernel as a library, which is licensed under GPL, while the application does not have to be licensed under it. It is analogue to this, when a LaTeX package is being used, I think, because all I write in my code is \usepackage{gpledpackage}. – bodo Aug 27 '12 at 14:03
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    @canaaerus: I doubt that linux applications make system calls themselves; they typically call the glibc (which is under the LGPL). And the FSF seems to believe that system calls crossing address space don't constitute aggregation. – Martin Schröder Aug 27 '12 at 14:21
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    @MartinSchröder The document you produce is not a program, but data. You aren't required to release under the GPL images produced with "The Gimp". – egreg Aug 27 '12 at 15:27
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    @egreg: TeX is an interpreter of a turing-complete programming language. – Martin Schröder Aug 27 '12 at 15:30
  • I'm also voting to close. This is one where if you really, really want to be within the law then you need to consult a lawyer. – Andrew Stacey Aug 27 '12 at 16:53
  • @MartinSchröder So what? Are you required to release under GPL the output of a Perl script? – egreg Aug 27 '12 at 17:57
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    @egreg: If it uses a CPAN module released under GPL: Yes. The license of the interpreter (which isn't GPL with perl) doesn't matter. – Martin Schröder Aug 27 '12 at 18:10
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    @MartinSchröder http://www.gnu.org/licenses/gpl-faq.html#WhatCaseIsOutputGPL – egreg Aug 27 '12 at 19:33
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    @egreg: http://www.gnu.org/licenses/gpl-faq.html#IfInterpreterIsGPL, http://www.gnu.org/licenses/gpl-faq.html#GPLAndPlugins - I think a LaTeX package is like a plugin to a document/a document class. – Martin Schröder Aug 27 '12 at 20:51
  • @AndrewStacey: Thank you for clarifying that even the GPL2 is too complex to be interpreted by non-lawyers. – Martin Schröder Aug 28 '12 at 11:19
  • @MartinSchröder I'm not sure if you are being sarcastic or not. Let me explain further why this is not a good fit for this site. As can be seen by looking at mailing lists, deciding on exactly what terminology applies to what with regard to licences is very complicated. It is therefore unlikely that a non-lawyer could answer this question in such a way as to correctly remove all ambiguity. I therefore think that any answer given here would be inherently unreliable and so to avoid spreading misinformation, this question should remain closed. – Andrew Stacey Aug 28 '12 at 11:36
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    @AndrewStacey: Then it should have been closed as OT, not as NARQ. And I'm not sarcastic. :-) – Martin Schröder Aug 28 '12 at 18:53
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    This question is misleading: The GPL is not independent from the national law. The answer differs probably a lot between different countries. Your question can not be answered »for the whole world«. However, the question is short, but a solid answer even for one country requires a lawyer who is familiar with copyright law, e.g. of your country (Germany) and GPL. So this is not the right place to ask this question. I'm not aware that such folks are reading questions here. That said: To what end are you asking this question? TeX and LaTeX have been around for decades and nobody ever doubted th – Keks Dose Aug 27 '12 at 14:33
  • See http://meta.stackexchange.com/q/70444/168273 and http://meta.stackexchange.com/q/139804/168273. This discussion belongs on meta.tex.sx – Martin Schröder Aug 27 '12 at 14:49
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    I'm not asking about licensing issuses regarding the TeX interpreter, but LaTeX packages. – Martin Schröder Aug 27 '12 at 14:50
  • @JosephWright The question without limitation to one specific country is nonsense, for legal reasons, as my answer explains. And even if Martin limits his question to Germany, nobody here will be able to give a solid, reliable answer, reason see above. Telling there is no answer, because the question is nonsense, is not a comment. – Keks Dose Aug 27 '12 at 15:01
  • @KeksDose no, you have it wrong. If the question is not a question, the correct thing is to (1) vote for the closure as NARQ and (2) possibly comment why you voted so. – yo' Aug 27 '12 at 19:39
  • @MartinSchröder If the document would fall under GPL, one should better not use pdfTeX/LuaTeX :) – Michael Jan 02 '13 at 17:09
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    Related: GPL-Licensed LaTeX template - implications for resulting work? – Martin Schröder Apr 11 '16 at 20:02

1 Answers1

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My current understanding of this is: All cases must be licensed under the GPL, as they are all modified versions, not aggregates. Or the LaTeX package is a library.

Which is why the GPL is IMHO the wrong FSF license for LaTeX packages; the LGPL would be much better.

Martin Schröder
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    Many people who make a contribution want to make it Free. GPL is what they know, what they have heard of, what they admire. I suspect that you are after an education issue (whether I agree with you or not :-) ). – Jim Hefferon Aug 27 '12 at 23:33