This question is related to Copyleft Multi-Licenced Copyright Notice.
I upload pictures on commons.wikimedia.org and I want to facilitate the reuse but I want derivatives stay "libre". Therefore I provide the wikicode {{self|cc-by-sa-all|cc-sa|GFDL|FAL}}
to multi-license them under some copyleft licenses:
- Any version of CC-BY-SA
- Any version of CC-SA
- Any version of GNU Free Documentation License (GFDL)
- Any version of Free Art License (FAL)
Questions about preventing license compatibility issues:
- Is it a good practice to license work under all versions of multiple-licenses?
- Should I provide more copyleft licenses? Or should I remove unnecessary ones?
I also mention these licenses within the JPEG comment. I think the text should stay short within the JPEG comment. This is my last version:
Copyright (c) 2016 my-name (ɔ) Copyleft
This work (photo) is multi-licensed under all versions of:
CC-BY-SA, CC-SA, GNU-Free-Documentation-License and Free-Art-License.
Therefore recipients can choose the version and the license
under which they want to use/modify/distribute this work.
Note: The symbol 'ɔ' is from Unicode U+0254 LATIN SMALL LETTER OPEN O that may be more widely available than Unicode U+2184 LATIN SMALL LETTER REVERSED C.
Last question:
Does this above notice meet the legal recommendations/requirements?
(Should it be written in another way? Should it be more verbose/shorten? ...)
EDIT Applying advices from Zizouz212's answer:
Copyright (c) 2016 my-name
This work (photo) is licensed under all versions of CC-BY-SA.
See http://creativecommons.org/licenses/by-sa/
You may select the version of your choice.