[cc-licenses] input requested: GPL/BY-SA compatibility - source

Francesco Poli invernomuto at paranoici.org
Thu Feb 5 17:19:00 EST 2015


On Thu, 5 Feb 2015 10:32:54 -0600 Sarah Pearson wrote:

[...]
> If one-way compatibility is declared, this will not change.  No new
> obligations would be imposed under the BY-SA license, either upon the
> original licensor or any downstream adapter who wishes to license their
> contributions under the GPL instead of BY-SA. This is the BY-SA side of the
> equation.
> 
> On the GPL side, those who adapt BY-SA works and choose to license their
> contributions under the GPL would, however, still have to comply with the
> GPL obligation to distribute or make available the work in the preferred
> form for making modifications. If a particular adapter cannot do this
> because she never received modifiable format from the BY-SA licensor and/or
> cannot convert the content to modifiable format, then that person would not
> be able to take advantage of the one-way compatibility declaration and use
> the GPL. This is our understanding of how one-way compatibility will
> operate from the GPL side of the equation,

I personally agree with this interpretation, even though I would not
have used the term "modifiable".
Actually, any (digital) format is modifiable (at worse, one can use a
hexadecimal editor and make any modifications to any file).

The issue is not whether the adapter has received a modifiable format
from the CC-by-sa licensor, but instead whether the adapter has
received or can obtain his/her preferred form for making modifications
(that is to say, source code, by the definition found in the GNU GPL).

Anyway, there's an additional consideration to be made.
If the potential adapter only has the CC-by-sa-licensed work in formats
A, B, or C and not in the preferred form P, he/she may decide that the
work is not worth using in his/her potential GPL-licensed adaptation
project.
But in some cases, he/she may desire to use the CC-by-sa-licensed work
so much that he/she accepts to modify it in one of the available
formats (say, B, for instance). After all, it's what he/she would do,
if he/she wanted to create a CC-by-sa-licensed adaptation...
This is suboptimal (this is why I think the source availability is
important), but it may happen.
At that point, the adapter has created a modified version of the
CC-by-sa-licensed work and has used format B as the form for making
modifications to the work. The adapter would use B as his/her preferred
form for making further modifications to his/her version of the work.
Hence, the preferred form for making modifications to the modified
version of the work is B.
The preferred form for making modifications to the original work is
still P, but the preferred form for making modifications to the
modified work is B (as shown by the adapter by practice).
I think that the modified version of the work may be distributed under
the GNU GPL with B as source code.

[...]
> Assuming this is the right interpretation, the next question is what
> actually constitutes the preferred form for making modifications for works
> other than software (musical recordings, text, photos, etc.). This is not
> as simple of a question for content as it is for software.

I don't think that this is so difficult as it is claimed to be.
I have already cited the essay I wrote on this topic:
http://www.inventati.org/frx/essays/softfrdm/whatissource.html




-- 
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 fsck is a four letter word...
..................................................... Francesco Poli .
 GnuPG key fpr == CA01 1147 9CD2 EFDF FB82  3925 3E1C 27E1 1F69 BFFE
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