Dmitry Alexandrov <dag@gnui.org> writes:

> Quoth <https://www.gnu.org/licenses/license-list.html#CC0> (emphasis mine):
> | A work released under CC0 is dedicated to the public domain to the fullest extent permitted by law. If that is not possible for any reason, CC0 also provides a *lax, permissive* license as a fallback. Both public domain works and the lax license provided by CC0 are compatible with the GNU GPL.
> |
> | If you want to release your non-software work to the public domain, we recommend you use CC0.
>
> Besides being GPL-compatible, itʼs FDL-compatible as well, while CC BY-SA is not.

That information is outdated. Since 2015 cc BY-SA is one-way compatible
to GPLv3: https://www.draketo.de/english/free-software/by-sa-gpl

Back then I invested a lot of time to make that happen, because I
required it to be able to use art from Battle for Wesnoth, Ryzom, and
Wikipedia in one roleplaying book.

Best wishes,
Arne
-- 
Unpolitisch sein
heißt politisch sein
ohne es zu merken