[copyleft-next] Compatibility with Eclipse Public License.

"Claes Wallin (韋嘉誠)" copyleft-next at clacke.user.lysator.liu.se
Fri Nov 9 07:35:07 UTC 2012


Sorry for bumping this discussion thread this late, but I discovered the 
Berkeley DB license* ("the BDB") and it made me think about what had 
been said here.

https://www.gnu.org/licenses/license-list.html#BerkeleyDB

Haven't looked at the BDB before, and I find it interesting. Taking into 
account only the numbered points, it might be the shortest example of a 
copyleft license in use in the field, even close to the shortest 
possible. It's close in form to a BSD-like license plus source requirement.

The FSF claims that the BDB is GPL compatible, I assume because it does 
not specify anything outside the bare minimum, in particular does not 
restrict any "further restrictions". Does it even propagate a guarantee 
of the four freedoms to modified versions of the software?


On 2012-10-12 13:45, Bradley M. Kuhn wrote:
> Mike Linksvayer wrote on  9 August:
>> there are cases where unambiguously MPL code could be included in a
>> copyleft-next project, if only copyleft-next allowed for it.
>
> Honestly, I'm not convinced that a truly strong copyleft can allow
> unilaterally inclusion of other copylefted code -- even weak -- without
> bilateral compatibility clauses.  We have to consider that such
> provisions while seemly safe on the surface may actually be manipulated
> to undermine the stronger copyleft by enterprising defense attorneys.

Is the BDB a counter-example to your thesis? Or is it not "truly strong"?

It seems to me that any license, that accepts whatever added conditions 
another license contains, will be forward-compatible with the more 
restrictive license. Either by enumerating certain allowed further 
restrictions, like the GPLv3 vs the AGPLv3, or by not explicitly 
forbidding any, like the BDB.


The point about using a weaker license to undermine a stronger one 
stands, whether if it means using a weaker, forward-compatible license 
to gradually rewrite the code base, or if it means some currently 
unknown license jujutsu.

-- 
    /c


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