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All text edits to Wikipedia fall under the Creative Commons Attribution/Share-Alike License (CC-BY-SA) with the copyright being retained by the original author; as of August 2009, most articles/edits are also dual-licensed under the GFDL. This is a guide for using multiple licensing of one's contributions made to Wikipedia so that they are in the public domain or licensed under alternative licenses in addition to the CC-BY-SA license (and GFDL, often). A number of users have chosen to release their contributions under some other license, or even to release their contributions into the public domain. Dual- or multi-licensing is not required or suggested by Wikipedia, but some users—for a variety of ideological or other reasons—prefer to release their contributions under a wider range of terms.

How it works[edit]

While all articles in Wikipedia are derivative works based on the first contribution made to the article, each article must be licensed under the CC-BY-SA license. However, individual contributions are not by themselves derivative works because they do not contain any of the original work, as the copyright still remains with the author. It is within one's rights to license those contributions under any terms one prefers, so long as one does it in addition to also being covered under the CC-BY-SA license.

Example: Alice and Boris are dual-licensors under the CC-BY-SA license and an incompatible License A. Candice only licenses under the CC-BY-SA license. Both the CC-BY-SA license and License A may be used in the following cases:

  • The initial revision started by Alice or Boris.
  • Any modifications by Alice or Boris up to, but not including, a modification made by Candice.
  • Possibly any changes made to the article after Candice by Alice or Boris which do not include the modification made by Candice.

For instance,

  1. Alice creates an article → version available under both licenses (CC-BY-SA license and incompatible License A).
  2. Boris makes an edit. → version remains available under both licenses
  3. Alice makes an edit. → version remains available under both licenses
  4. Candice makes an edit. → version available only under the CC-BY-SA license, unless Candice's edit was so trivial that no one would care (e.g., fixing a typo)
  5. Boris makes an edit. → version available only under the CC-BY-SA license, unless Candice's edit can be separated from the rest of the article (e.g., by removing a paragraph).

One must use some common sense in determining whether Candace's edits were trivial or separable enough that Alice's original dual license survives into Versions 4 or 5. Where Candice's contributions do upset the dual license, you may not use her contributions under the incompatible License A unless you convince her to release her contributions under that license.


The case for multiple licenses[edit]

  • To be friendly and able to use the material with other open projects which use an incompatible license other than the GFDL or CC-BY-SA license.
  • To make licensing of material less restrictive. For example, public domain allows totally unrestricted usage for any purpose.
  • If enough people use a different compatible license, large numbers of articles can be dual licensed.
  • To satisfy a copyright holder's ideological or philosophical opinions, such as a belief that information should be absolutely unrestricted (released into the public domain).
  • It is not a policy but instead totally optional.

The case against multiple licenses[edit]

  • A third-party can take the material and modify it under the terms of License A and not release it under the CC-BY-SA license. This may create an incompatible fork which prevents those modifications from being able to be used by Wikipedia under the CC-BY-SA license. Using the CC-BY-SA license alone prevents this and ensures that any derived works can always be used on Wikipedia without modification. Note that under the official Wikipedia interpretation of what constitutes an aggregate work, it is already possible to add paragraphs or images which are not CC-BY-SA licensed and thus create an incompatible fork.
  • For heavily edited articles, the process of manually sifting through the rat's nest of edits to determine whether an article, or a part of an article, is available outside the CC-BY-SA license becomes more error-prone as the number of edits to the article increases. This makes it more likely that an article only available under the CC-BY-SA license will be erroneously labeled otherwise, and subsequently used in violation of the license.
  • One could hypothesize that some ideological fanatics might systematically revert, or eliminate, changes made only under the CC-BY-SA license to their favorite articles, so that they remain available under an incompatible license.

Why it might not matter[edit]

  • Figuring out who has licensed their contributions under a conceivably large number of different licenses can be cumbersome at best. It may be possible, but extremely difficult, to figure out what modifications can be used under a particular license.
  • Even if those who dual-license their contributions can be identified, the dual-licensed content may not be useful. For example, only the first, third and fifth words of a given sentence may be dual licensed, while the rest are CC-BY-SA-only. Obviously, the dual-licensed content would be of very little use.
  • As of GFDL 1.3, wiki content can be (and for Wikipedia, has been) relicensed under CC BY-SA (see the license for the conditions for relicensing).

Using multiple licenses[edit]

In general, users make their multi-licensing desires known on their user page by way of a banner or some description of their wishes (See User:Jamesday for a complicated example). This is often simply accomplished by adding a pre-made template. See the full selection of licensing templates available.

The scope of a license may vary. For instance, a user may choose to license main namespace changes in one license and talk namespace changes in another. In addition, a user may consider releasing all minor changes into the public domain in order to avoid the problems that trivial changes may have in trying to release an article in a specific license. At the same time, meaningful non-minor changes can be released under a more restrictive license. In the case of the GNU licenses, one can specify certain restrictions, such as specifying a particular version of the license instead of any.

Using the CC-BY-SA license and GFDL only[edit]

Unless you explicitly specify otherwise, all contributions to Wikipedia are dual-licensed under the CC-BY-SA license and the GFDL; therefore, if you elect not to adopt additional licenses, no action is necessary. Even if you use said two licenses exclusively, you may wish to communicate your preference on your User page, such as by using {{NoMultiLicense}}.

List of terms for use[edit]

  • Creative Commons License
    • Version 1.0
      • Creative Commons Attribution-ShareAlike Draft (CC-by-sa) {{DualLicenseWithCC-BySA}}
      • Creative Commons ShareAlike (CC-sa)
      • Creative Commons NonCommercial-ShareAlike (CC-nc-sa)
      • Creative Commons NoDerivs (CC-nd)
      • Creative Commons NonCommercial-NoDerivs (CC-nc-nd)
      • Creative Commons NonCommercial (CC-nc)
    • Version 2.0
      • Creative Commons Attribution-ShareAlike (CC-by-sa) {{MultiLicenseWithCC-BySA-Any}}
        • This license is very similar to the GFDL used by Wikipedia and is thus very popular.
      • Creative Commons Attribution-NonCommercial-ShareAlike (CC-by-nc-sa)
      • Creative Commons Attribution (CC-by)
      • Creative Commons Attribution-NoDerivs (CC-by-nd)
      • Creative Commons Attribution-NonCommercial-NoDerivs (CC-by-nc-nd)
      • Creative Commons Attribution-NonCommercial (CC-by-nc)
    • Version 3.0
      • Creative Commons Attribution-ShareAlike (CC-by-sa)
        • Wikipedia is already dual-licensed (or singly-licensed in the case of pages incorporating CC-BY-SA content from outside sources) under this as of the June 15, 2009 relicensing.
  • Public domain {{Public domain release}}
    • Many users do not wish their contributions to be restricted in any way.
  • CC-0 {{CC-0 Release}}
    • The same as the Public domain, but with fail safes in place in case Public domain isn't possible in some jurisdictions
  • GNU Licenses
  • FreeBSD Documentation License
  • BSD Documentation License
  • BSD license

See also[edit]