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-SAAny version of CC-SAAny 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 () 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 '' 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.
JPEG comment to convey Copyleft Multi-Licenced Copyright Notice
copyright;copyleft;multi licensing;license notice;wikipedia
You've got a couple issues.First off, is the way you assert your copyright. Particularly this: (emphasis mine)Copyright (c) 2016 my-name () CopyleftThe issue is that the term copyleft is not a legally defined term. Even this Wikipedia article claims that the addition of this text has no legal significance whatsoever. Second, I'm not entirely sure what you're trying to accomplish by offering your work over multiple licenses. Ideally, you should keep things under a sole license. The biggest reason for offering a work over multiple licenses is so that others can distribute their own modifications under other various licenses, and in the case that licenses are incompatible with each other, to provide optimum usage across the broad spectrum of licenses.Also, as a quick note, there is no CC SA license. ShareAlike is just a concept, that is embedded into the Creative Commons Attribution license (CC BY), and isn't a license in itself.What would I recommend?Unless the offering over multiple licenses provides advantages for yourself and for others that may make use of your work, you should really keep things simple, concise and to the point. Offer the work over a sole license, and the best bet would likely be the Creative Commons Attribution ShareAlike license.