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Re: ELPA license, LGPL + additional restrictions


thanks for your answer.

On Fri, Nov 02, 2012 at 04:49:08PM +0100, Francesco Poli wrote:
> On Fri, 2 Nov 2012 16:13:10 +0100 Michael Banck wrote:
> > The development version (not in testing/unstable for now) of cp2k, which
> > is under the GPLv2+ itself has just added support for the ELPA library:
> [...]
> > they say ELPA is licensed
> > under the LGPL with some additional clauses.
> [...]
> > It says this:
> >
> > --8<--
> [...]
> > The code is distributed under ALMOST all of the the terms of the GNU
> > Lesser General Public License version 3 (LGPL).
> [...]
> > While we are not allowed to alter the license texts as written in those 
> > files, IN ADDITION our own license prescribes two important
> > modifications / clarifications to the original lgpl.txt:
> > 
> > - In point 2., clause b) - stating that that you may redistribute
> >   under the terms of the plain GNU GPL - shall NOT apply. In other
> >   words, if you redistribute, you MUST keep the additional permissions
> >   of the LGPL v3 in place.
> > 
> > - If you redistribute, you must redistribute under the terms of the
> >   LGPL version specified here. Using later or earlier versions
> >   published by anyone except the ELPA copyright holders is
> >   not allowed. 
> > 
> [...]
> > --8<--
> > 
> > My main question would be whether the above can considered
> > GPLv2+-compatible, i.e. whether cp2k can use this.
> Dear Michael,
> first of all the GNU LGPL v3 is not compatible with the GNU GPL v2, but
> only with the GNU GPL v3.
> Hence, even a plainly LGPLv3-licensed work would be considered
> compatible with a GPLv2+-licensed work, just because of that plus sign
> (assuming that "v2+" means "v2 or later", as usual), but not with a
> GPLv2only-licensed work.

Right, that's why I explicitly mentioned that CP2K is under the GPLv2+.
> However, this case is much more complicated, since there are two
> additional clauses, with respect to the GNU LGPL v3.
> The first clause disables one clause of the GNU LGPL v3, dropping its
> one-way convertibility to the ordinary GPL.
> My own personal opinion is that such additional restriction (which I am
> not even sure can actually be added this way to the GNU LGPL v3) makes
> the result GPL-incompatible.
> The reason is that the GNU GPL insists that the whole work be available
> under the terms of the GNU GPL, but the above restriction makes this
> impossible for the ELPA library.

Now that you mention it I guess that clause was explicitly included in
the LGPLv3 in order to maintain GPL-compatibility by design, right?

In that case, I will bring it up with the CP2K maintainers.  They do not
distribute binaries though, only a source repository and sometimes
release tarballs.  Is this already an issue as they are shipping the
ELPA source in their tree right now?
> The second clause seems actually unnecessary to me: as specified by
> Section 6 of the GNU LGPL v3, a library is not compelled to enable the
> "or later" mechanism:
> [...]
> | If the
> | Library as you received it specifies that a certain numbered version
> | of the GNU Lesser General Public License "or any later version"
> | applies to it, you have the option of following the terms and
> | conditions either of that published version or of any later version
> | published by the Free Software Foundation.
> [...]
> It says "*If* the Library [...] specifies [...]", so the Library may
> specify otherwise (for instance "v3 only").
> The LGPL text even allow the licensor to elect a "proxy" that will
> decide whether future versions shall apply...
> Hence, I personally think that there's no need to add this second
> clause to achieve this result.
> I am under the impression that it should suffice to specify "v3 only",
> which is already the case:


Let's hope the ELPA people reconsider.  It is pretty difficult for me to
second guess why exactly they revoke the GPL compat clause (which would
not be an "advantage" to anybody *less* Free Software happy than they
are, AFAICT), maybe they are just confused about it and/or discarded the
GPL due to their corporate (or rather publically funded organisation's)



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