One of the topics commented for the discussion of the CC 4.0 licenses is
the option to give a one-way compatibility between the CC-By-SA and the
GPL. At a first glance, it looks like a great idea, which would allow more
intercompatibility between free licenses, but there is an issue with the
GPL's requirement to provide complete corresponding source code.
First of all, there's no consensus on what can be taken as the source code
of every license-able work. For written works, it would be the editable
file (in Word format, for example). But what about audiovisual works?
Usually those are composed by several raw files (variously named "stems",
"assets", "resources", and so on). Except for photographs (where there is
only one raw file, unedited except for the color balance), most other
works of this kind are composed themselves by several files, and the set
of commands that are used to combine them (the project file for audio and
video, the image editor's full file for images). And then there's the
question of how much must be an individual asset edited, in order to
require the release of both the original file and the commands to edit it.
Secondly, as it should be well-known, most works under CC licenses
(especially audiovisual works) don't release the source code, either
because of the size of the files, or because those files weren't preserved
at all. Also, the GPL requires that the assets and project files are "in a
format that is publicly documented (and with an implementation available
to the public in source code form), and must require no special password
or key for unpacking, reading or copying". This outlaws releasing the
project if it was made with non-free software (like Photoshop, Word, Sony
Vegas and many more).
That leaves two options for relicensing: allowing it only if those works
already comply with releasing full corresponding source, or else
retroactively forcing authors to comply with the new license terms. The
latter, however, would impose additional requirements to the authors in a
retroactive fashion, and it may be difficult or impossible for them to
comply (for example, by remaking the file in a free software tool). And to
make things worse, it would also require the original author to
recursively impose the same requirement on all the authors of all the
assets used on the work.
This doesn't mean that there shouldn't be any compatibility with the GPL,
but it must be limited to works that already comply with the GPL's
requirement for source code (here meaning full assets, full instructions
for editing the assets in their final form, and all files under a free
format). This would prevent legal issues with the derivative GPL works,
and avoid to impose terms retroactively on authors that may not be located
or may not release the source on the required terms.
- Carlos Solís
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