Subject: Re: GPLv3 draft
From: Bernard Lang <Bernard.Lang@inria.fr>
Date: Tue, 4 Apr 2006 21:41:53 +0200

 * Norbert Bollow <nb@bollow.ch>, le 04-04-06, a écrit:
> Stephen J. Turnbull <turnbull@sk.tsukuba.ac.jp> wrote:
> 
> > Both the GPLv2 and draft GPLv3 require that redistributions take place
> > under identical terms (sections 2(b) and 6 in GPLv2).  GPLv3 contains
> > an explicit DRM clause, GPLv2 does not.  Therefore, you may not
> > combine GPLv2 code with GPLv3 code without separate, explicit
> > permission from at least one of the authors to use the license
> > specified by the other.[1]
> 
> This argument is incorrect, because the DRM clause of the
> GPLv3 draft does not impose any GPLv2-incompatible
> restrictions.

two copyleft licences that differ by one word are incompatible, unless
one of them explicitly allows switching to the other one (which is
what, Cecill does with respect to GPL v2).  But then the former is not
really fully copyleft, since it allows the switching, i.e. a change of
licence.

Did I make it more clear?

Cordialement

Bernard

> Specifically, the text of the DRM clause is what I'm quoting with
> ":::" is the following (I'm quoting the entire text of paragraph
> 3 of GPLv3 draft1, in chunks, with my comments after each chunk).
> 
> ::: As a free software license, this License intrinsically disfavors
> ::: technical attempts to restrict users' freedom to copy, modify, and
> ::: share copyrighted works. Each of its provisions shall be interpreted
> ::: in light of this specific declaration of the licensor's
> ::: intent.
> 
> This declaration of intent by itself is not GPLv2-incompatible.
> It could cause the license to be GPLv2-incompatible if there is
> any part of the license which is ambiguous and which because of
> this declaration has to be interpreted in a GPLv2-incompatible
> manner.  However, as far as I can see, this does not seem to be
> the case.
> 
> ::: Regardless of any other provision of this License, no
> ::: permission is given to distribute covered works that illegally
> ::: invade users' privacy,
> 
> This does not impose any restriction on recipients' exercise of
> the rights granted in the GPLv2, because distributing a program
> that "illegally invades users' privacy" is essentially by definition
> an illegal act.  The restriction has been imposed by a law, and it
> exists also for those who distribute under GPLv2.  Hence this
> restriction is not GPLv2-incompatible.
> 
> ::: nor for modes of distribution that deny users that run covered
> ::: works the full exercise of the legal rights granted by this
> ::: License.
> 
> This forbids "modes of distribution" that somehow subvert copyleft.
> Such distribution is not allowed under GPLv2.  Hence there is
> nothing GPLv2-incompatible about this clause.
> 
> ::: No covered work constitutes part of an effective technological
> ::: protection measure: that is to say, distribution of a covered work
> ::: as part of a system to generate or access certain data constitutes
> ::: general permission at least for development, distribution and use,
> ::: under this License, of other software capable of accessing the same
> ::: data. 
> 
> This permission is also implied by the terms of GPLv2.
> 
> And here we're at the end of the "Digital Restrictions Management"
> paragraph of the GPLv3 draft already.  It does not impose any
> restrictions on distributors of a partly GPLv2, partly GPLv3 program
> which are not imposed on the distributors already by GPLv2 together
> with whatever laws exist in the jurisdiction of the distributor, and
> it does not require these distributors to grant any permissions which
> the GPLv2 does not already require to grant.
> 
> This is precisely what you have to achieve if you want to
> write a GPLv2-compatible license.
> 
> 
> Stephen J. Turnbull <turnbull@sk.tsukuba.ac.jp> also wrote,
> directed at me:
> 
> > You are welcome to your opinion.  However, one who doesn't understand
> > the relationship between strong copyleft and license incompatibility
> > is not in a position to discuss others' misunderstandings or FUD.
> 
> I assure you that I understand the relationship between strong
> copyleft and license incompatibility.
> 
> Greetings,
> Norbert.

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