I am adding this note as a consequence of this discussion on Pixls.us:
https://discuss.pixls.us/t/gimp-patterns-and-the-gpl-license/35969
Now we were always very clear that GIMP can be used for whatever use you want
and that the project doesn't intent to claim any rights on produced artworks.
There is even a FAQ entry about the fact we don't intend to put any restriction
on people's work (though this FAQ entry was added in 2015 AFAICS):
https://www.gimp.org/docs/userfaq.html#can-i-use-gimp-commercially
Yet it's better to be as clear as possible. Therefore this new note in the
LICENSE file will serve to make sure any new data is properly licensed CC0 by
the simple fact of contributing it.
This is similar to the fact that people contributing patches to core GIMP (app/)
are implicitly licensing it as GPL. Now people contributing data to data/ are
implicitly licensing it as CC0 as per our LICENSE file.
Our Symbolic icon theme comes from the art-libre theme now archived by
the GNOME design team. It had various authors, including originally
Jakub Steiner and Barbara Muraus, then jEsuSdA, Klaus Staedtler,
Alexandre Prokoudine and Aryeom Han. Various other people tweaked the
icons and may have contributed. See the git log for details.
The Color icon theme is more of an original work by Klaus Staedtler, as
I understand it, with some additional icons by Alexandre Prokoudine,
Aryeom Han and other contributors. See the git log for details.
This makes licensing clearer for these specific subsets of the project.
2003-07-26 Adam D. Moss <adam@gimp.org>
* LICENSE: (new file) Explain the mix of licenses within
the GIMP distribution, and make an explicit statement clarifying
our position on invoking methods in GPL-implemented code from
non-GPL plugins/extentions via libgimp and/or the pdb (ie. that
this does not automatically GPL-infect the program doing the
invoking, which is otherwise an ambiguity in the GPL).
Jehan