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Guide to the dual-license

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Note: The English Wikipedia Multi-licensing page contains more information on multiple licensing schemes. It is meant to replace this page, as this page already consists of lists of those who are in dual-licensing schemes other than the Creative Commons licenses (such as public domain).

This is a short guide to contributions which are dual-licensed under the GFDL and the Creative Commons Attribution Share-Alike license (henceforth CC).

Why dual licenses

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The GFDL is very similar to the CC license; however, the CC license is very attractive because it is very clearly and simply explained. Some projects opt to use the CC instead of the GFDL (although not necessarily for the same reason) and it would be nice if these projects could borrow Wikipedia material. Because the GFDL and CC are currently incompatible, this is not possible.

Since I own the copyright to my contribution, I can choose to dual-license it if I want (subject to the original author's right to control derivative works of his work). My hope is that if enough people do the same, then we could make large swathes of Wikipedia text available to CC users.

Why not dual license

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It adds an additional layer of complication onto the already difficult GFDL licensing. It makes things hard for other people -- not for the dual licensor -- which is pretty unfair. It's confusing. It's got a very tiny audience -- almost anyone can use the GFDL license, with only a few folks who can't. And Wikipedia is working with the Free Software Foundation to try to make the GFDL compatible with other copyleft content licenses.

The biggest reason not to dual licence is that it is another way that your dual-licenced content could become incompatible with Wikipedia.

  1. User X copies your content which is dual licenced from Wikipedia
  2. User X works on this content under a CC licence and expands it

Now, if user X does not decide to dual-licence his modifications under the GFDL ( as opposed to what happens by default: his modifications are licenced under the CC only ) you and others would be not allowed to merge his changes back into wikipedia which you otherwise could have done, a dual licencing scheme leads to situations when copied content becomes incompatible with the parent.

If you just use GFDL this only happens if the modifier adds front-cover texts, back-cover texts, or invariant sections.

See the talk page for a continuation of this discussion.

How to dual license

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The CC license may be applied to

  • The initial revision of any article started by a dual licensor (such as myself)
  • Any subsequent revisions by a dual licensor up to the first modification by a non-dual licensor
  • Any revisions by a dual licensor after that (perhaps)

Imagine if Carlos and Christina (some dual licensors) and Gabriel (a non dual licensor) work on the same article.

  1. Carlos starts the article
  2. Christina makes some edits
  3. Carlos makes some more edits
  4. Gabriel makes some edits
  5. Carlos makes more edits

If you wanted to use the CC, you would only be able to take the first 3 revisions of the article. Version 4 is not possible because Gabriel is a non-dual-licensor.

Version 5 might not possible even though it was Carlos who made the modification. This is because he based his modification on Gabriel's work. If you wanted to use the latest version of the article, you would have to convince Gabriel to also become a dual licensor.

There is a good news: If the modification made by Carlos in Version 5 was in a different part of the document than Version4, you can likely use it, minus the modifications made in by Gabriel. This is useful if the majority of the document was written by dual-licensors, with the occasional tweak by a non dual-licensor (Gabriel). As for minusing the modifications made by Gabriel, you might also find it useful to apply a little common sense. Say Version 4 consisted of Gabriel fixing a typo. Do you seriously think he's going to come after you for copyright violation? After all, you could have fixed that little typo yourself when you took over the document.

I want to be a dual-licensor too

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If you are on Wikimedia Commons, include the following code in your user page:

{{DualLicenseWithCC-BySA}} - version 1.0 (Template)
{{DualLicenseWithCC-BySA-2.0}} - version 2.0 (Template)
{{DualLicenseWithCC-BySA-Dual}} - version 1.0 and version 2.0 (Template)
{{DualLicenseWithCC-BySA-to-2.5}} - version 1.0, version 2.0, and version 2.5 (Template)
{{DualLicenseWithCC-BySA-to-3.0}} - version 1.0, version 2.0, version 2.5, and version 3.0 (Template)
{{MultiLicenseWithCC-BySA-Any}} - all attribution share-alike versions (Template)
{{DualLicenseWithCC-BySA-Future}} - all attribution share-alike versions, including all future versions (Template)

If you are on the English Wikipedia, use:

{{DualLicenseWithCC-BySA}} - version 1.0 (Template)
{{DualLicenseWithCC-BySA-2.0}} - version 2.0 (Template)
{{DualLicenseWithCC-BySA-Dual}} - version 1.0 and version 2.0 (Template)
{{DualLicenseWithCC-BySA-to-2.5}} - version 1.0, version 2.0, and version 2.5 (Template)
{{DualLicenseWithCC-BySA-to-3.0}} - version 1.0, version 2.0, version 2.5, and version 3.0 (Template)
{{MultiLicenseWithCC-BySA-Any}} - all attribution sharealike versions (Template)
{{DualLicenseWithCC-BySA-Future}} - all attribution share-alike versions, including all future versions (Template)

on the German Wikipedia, use:

{{Doppellizenz CC-by-sa/2.0/de}} - version 2.0 (germany)
{{Doppellizenz CC-by-sa/2.5}} - version 2.5
{{Doppellizenz CC-by-sa/3.0}} - version 3.0
{{Doppellizenz CC-by-sa/3.0/de}} - version 3.0 (germany)

on the French Wikipedia, use:

{{Double licence}}


on the Polish Wikipedia, use:

{{self2|GFDL|cc-by-sa-2.5}} (or other CC versions)


Otherwise, copy the message to your project's Template: namespace and use that.

List of dual licensors

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To satisfy my curiosity about the progress of this experiment, please put your username on this list if you dual-license your contributions with the CC-by-sa or similar.

For a more complete/accurate/up-to-date list, go to the relevant template page, and use 'What links here' e.g. Links to 'DualLicenseWithCC-BySA-Dual' to see which user pages transclude the template.

CC-BY-SA to 3.0

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To use this license you may use {{DualLicenseWithCC-BySA-to-3.0}}

CC-BY-SA 2.5

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To use this license you may use {{DualLicenseWithCC-BySA-2.5}}

CC-BY-SA 2.0

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To use this license you may use {{DualLicenseWithCC-BySA-2.0}}

CC-BY-SA 1.0

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English user pages:

Polish user pages:

German user pages:

CC-BY-SA (only) for photographs

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General licensing

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  • Jamesday 09:41, 28 Jan 2004 (UTC) A wide range of licenses on my user page.

Public domain

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  • TomK32 (german) - consider my edits and works in Wikipedia as public domain.
  • Toby Bartels seems to put all his contributions into the public domain. --Zenogantner 16:21, 30 Apr 2004 (UTC)
    • This is not strictly true; I license all of my contributions perfectly freely, but the copyright ownership does not change. The legal significance of this is (I think) that I don't have to own anything to begin with in order to license it. If I create a derivative work, then it may have huge restrictions on it, depending on the status of the original work; I cannot (IIUC) place it in the PD because I do not own it completely. Nevertheless, I give you permission to do anything that you want with my derivative work, so if the author of the original work gives you permission to do something (say GNU FDL, or CC-by-nc-sa, or a print run of 100000 copies with a 5-cent royalty paid on each copy that is not destroyed unsold, or whatever), then you don't need to get any further permission from me. (Incidentally, this applies to all of my creative work, regardless of whether it's on Wikimedia; and it applies to patent rights as well as to copyright rights, in case I ever develop an algorithm. See http://tobybartels.name/copyright/.) -- Toby Bartels 05:56, 18 Nov 2004 (UTC)
  • en:User:Eloquence says on his user page: All my contributions to Wikipedia are in the public domain unless otherwise noted. Feel free to use them as you wish.
  • en:User:Eiffel All my contributions to Wikipedia are released to the public domain.
  • en:User:Lee Daniel Crocker I explicitly place all creative works original to me in the public domain.
  • de:Benutzer:Dishayloo - my edits in the Wikipedia can be counted as PD
  • de:Benutzer:Srittau, en:User:Srittau - all my contributions to the Wikipedia are Public Domain
  • Pcb21 (non-main namespace edits, and all edits on meta)
  • Seth Ilys - main namespace text edits, from his user page: I release of all of my text contributions to Wikipedia pages in the article namespace into the public domain in all jurisdictions worldwide.
  • en:User:Ashibaka - all my contributions are PD
  • en:User:Lost.goblin - All my contributions to Wikipedia are released to the public domain
  • en:User:Kaldari - all of my contributions to Wikipedia are public domain.
  • en:User:Alphax - all minor edits within the main namespace.
  • de:User:Saperaud - all of my contributions to Wikipedia are public domain.
  • en:User:fxer - Every single one of my contributions is public domain. Dump the ego people, go public domain!
  • en:User:Thinboy00 - All minor edits.
  • User:Diti — Every contribution outside (main) namespace. Otherwise CC-by-3.0. Diti (talk to the penguin) 17:42, 26 December 2008 (UTC)[reply]
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