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Re: [libreplanet-discuss] Potential of the Sleepycat License


From: Aaron Wolf
Subject: Re: [libreplanet-discuss] Potential of the Sleepycat License
Date: Mon, 17 Apr 2017 16:07:37 -0700

On 04/17/2017 03:02 PM, Michael Pagan wrote:
> Aaron Wolf <address@hidden> wrote:
>> On 04/16/2017 08:32 PM, Michael Pagan wrote:
>>
>>> the work must be under the same license as the original work, too.
>>
>> To be picky and pedantic, what matters for copyleft is merely that the
>> freedoms may not be stripped away. It doesn't matter whether derivatives
>> have the exact same license, that's just the normal mechanism for
>> copyleft. GPLv3 code allows use in AGPLv3 and that's not strictly the
>> same license. If it is ever released, copyleft-next might be a license
>> that retains copyleft by specifying derivatives to use either the same
>> *or* AGPL…
>>
>> What defines copyleft is that stripping away freedoms is itself
>> copyright violation. Any mechanism achieving that result is copyleft.
> 
> Thank you for the clarification!
> 
> I usually see that most copyleft licenses require users to use the same
> license upon redistribution or distribution of modified copies, but as
> long as the freedoms go with the code, then copyleft is still in
> effect no what which license is used... as I understand it.
> 
> Question, though:
> 
> I have noticed that the GNU.org hackers maintain a list of copyleft
> licenses, and that they even label which ones are compatible with the
> GNU GPL.  Do they identify compatibility, so that in case someone wants
> to use a similar copyleft license (which may contain slightly different
> provisions) they can switch?
> 
> I guess this could make sense, for instance: Perhaps going from GPL to
> AGPL, when a simple shell script gets refactored into a web client.
> 
> 

Yeah, incompatibility gets in the way of freedoms, it's a serious and
unfortunate side-effect of copyleft's mechanisms. Two bits of code could
work together technically, both are free, but you can't mix them because
of incompatible licenses. It's the most legitimate complaint about
copyleft, and it's entirely solved if everyone sticks to only a
compatible set of copyleft licenses.

GPL compatibility includes permissive licenses though. BSD licenses are
non-copyleft but GPL compatible because none of the BSD terms are
incompatible with GPL, so you can mix BSD-licensed code into a GPL
project. You can't go the other way around, so it's one-direction
compatibility, which is how most GPL compatibility works.


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