Wikipedia:Multi-licensing

Example: Alice and Boris are dual-licensors under the CC-BY-SA license and GFDL. Alice also chooses to license her content under Incompatible License A, for instance CC-By-NC, so that it can be incorporated into non-commercial material elsewhere. Candice's content, which she coauthored and previously published elsewhere, only licenses under the CC-BY-SA license. Both the CC-BY-SA license and GFDL may be used in the following cases:

For instance,

One must use some common sense in determining whether Boris's and Candace's edits were trivial or separable enough that Alice's original multiple license survives into Versions 2 and beyond. Where Boris's contributions do upset the multiple license, you may not use his contributions under CC-By-NC unless you convince him to release his contributions under that license. Where Candice's contributions upset license, you may not use her contributions under GFDL or CC-By-NC unless you convince her to release her contributions under those licenses.

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.

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