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From: Bjørn Roald (bjorn_at_[hidden])
Date: 2006-08-07 18:01:56

Guillaume Melquiond skrev:
> Le lundi 07 août 2006 à 08:24 +0200, Bjørn Roald a écrit :
>> I don't think you can dual license GPL with _less_ restrictive licenses,
>> e.g. the Boost license. Those licenses add too much freedom. Freedom
>> to use and hide is not compatible with the GPL. That said, you can use
>> Boost Software Licensed software in a GPL project. That is what the GPL
>> compatibility pages is about:
> [...]
>> Q: Can I dual-license my software under both the GPL and the Boost
>> Software License?
>> A: The Boost Software License allow this, but not the GPL. This is not
>> allowed due to the copyleft restrictions in the GPL. See:
>> Specifically, the problem
>> is with the GPL requiring all modified and extended versions of the
>> program to be free as well. The Boost Software License allow the
>> licensee to make non-free modified and extended versions of the program.
> I don't agree with this interpretation. When you multi-license a
> "software", the "user" is not bound by all the licenses at once.

The user is not, agreed. This was not advice to the user.

> In
> particular, breaking one of the licenses does not simultaneously break
> all the other licenses.
Again from the user perspective, this is true. But it kind of proves my
point, which is that if you as the copyright holder dual-license under
GPL and BSL you break the intent of the GPL license in such a way that
the copyleft restrictions (or rights) that the license provides is no
longer guarantied. Hence the correct advice may be that you may do
it, but it is unlikely to make any sense. Since BSL licensed
software is compatible with use in GPL projects it make more sence to
use BSL only if you do not require the copyleft or other restrictions in
GPL which you lift by adding the BSL license.

On important point here is that what can be interpreted as
restrictions in the GPL really are carefully crafted wording to provide
"freedom" to the GNU society . Hence effectively lifting them with a
dual license, is breaking the intent of the GPL. I do not think such
practice will be endorsed by the FSF. That does not mean that you as a
copyright holder break any laws. Those are different issues.

> As a consequence, if the user is allowed to
> "use" the software under the terms of the GPL and if she is also allowed
> to use it under the terms of the Boost license, she can decide that the
> only the Boost license applies and then she can use the software in
> strict accordance with this license.
Yes, that make sense.

best regards

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