An old question of EGE's
Last year, Edmund Grimley Evans wrote:
> Suppose we have:
>
> licence A that forces you to release modifications under a
> BSD-licence to the whole world
>
> licence B that forces you to release modifications under a
> BSD-licence to the original authors and a GPL-licence to the whole
> world
>
> licence C that forces you to release modifications under a
> GPL-licence to the whole world
>
> Then licence A gives fewer permissions than licence B, and licence B
> gives fewer permissions than licence C. If you dual-license
> something under A and B that's the same as licensing it under B
> (because licence B doesn't stop you from also BSD-licensing your
> modifications to the whole world), and if you dual-license something
> under B and C that's the same as licensing it under C (because
> licence C doesn't stop you from also BSD-licensing your
> modifications to the original authors).
>
> You seem to be saying that A and C are DFSG-free, but B isn't. So
> something released with license A is free, but software
> dual-licensed with A and B is non-free. I seem to be seeing or
> imagining some kind of paradox here ...
I'm not convinced that either A or C are free, but for the purposes of
this thread I'm willing to temporarily assume so. But I'm going to
rephrase Edmund's B to make something clear:
* license B' that forces you to release modifications under a BSD
license to the original authors and forces you to release
modifications under a GPL-license to the whole world.
You can't release your changes under a copyleft to the original
author.
I don't know of any Free license which claims to forbid me from using
a copyleft, not even the BSD Protection License (discussed around the
same time the parent of this message was posted, and available at
http://web.comlab.ox.ac.uk/oucl/work/colin.percival/source/BSDPL.html
).
The BSD Protection License is *probably* free, if awkwardly phrased
and unfortunate in intent. It is basically a BSD copyleft, in that it
preserves everybody's right to take software proprietary, and
prohibits contamination from copylefts like the GPL.
So there you can release your software to the original author under
the same terms you received it from him -- he can take it proprietary,
or he can distribute under the BSDPL. But even he can't then combine
your work with something he has under the GPL.
The idea from DFSG 3 that modifications must be able to be
"distributed under the same terms as the license of the
original software" seems to be an important component of Freedom. I
really do think, on consideration, that this means the actual license
I had, not a big document listing all of the licenses I might get if I
paid the author or became a teacher or ceased to operate nuclear power
plants.
-Brian
--
Brian Sniffen bts@alum.mit.edu
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