David A. Wheeler's Blog

Sat, 23 May 2009

Wikipedia changes its license

The Wikimedia Foundation (WMF) will change the licensing terms on all its materials — including Wikipedia. Now, all of its existing material will be released under the Creative Commons Attribution-ShareAlike (CC-BY-SA) license in addition to the current GNU Free Documentation License (GFDL). The WMF says “This change is meant to advance the WMF’s mission by increasing the compatibility and availability of free content.” This means that Wikipedia material can now be combined with the vast amount of CC-BY-SA licensed material, and Wikipedia can now include the volumes of CC-BY-SA material (that material will just be CC-BY-SA). It also makes it easier to use Wikipedia material (and other material from the Wikimedia Foundation).

I think this is a good thing overall. Incompatible licenses are a real scourge on community-developed works. Past experience shows that license incompatibility can be a real problem for free-libre/ open source software (FLOSS or OSS), in particular. Bruce Perens warned about FLOSS license incompatibility back in 1999! As I argue in Make Your Open Source Software GPL-Compatible. Or Else, you should release free-libre/ open source software (FLOSS) using a GPL-compatible license. You don’t need to use the GPL, but using a GPL-compatible license (like the MIT, BSD-new, LGPL, or GPL) so means that people can combine your software with other software to create larger works. I show how this works in The Free-Libre / Open Source Software (FLOSS) License Slide, which has a simple graph showing how common FLOSS licenses can work together. Wikipedia articles aren’t software, but the principles still apply - licenses need to enable community-developed works, not disable them.

Now, nothing is perfect. One nice benefit of the GNU Free Documentation License (GFDL) is that it requires that readers be able to get editable versions whose format specification is available to the public (for details, see its text on “transparent” copies). This is a really nice feature of the GFDL; it counters some of the problems of proprietary formats.

The GFDL has many problems, though, when used for short works like Wikipedia articles or images. Most obviously, it requires that you include the entire text of the license with each work (see GFDL 1.3 section 2). That’s no problem for large manuals, which is what the GFDL was designed for, but it’s a big problem for short works. Nobody likes having a license longer than the article it’s attached to! This is one reason why CC-BY-SA is so widely used for short works - and since Wikipedia is primarily a large set of short works, it makes sense. Which is why I (and many others) voted to approve this change.

Now it’s certainly true that people also complain that the GFDL allows the addition of unmodifiable sections. But many GFDL items don’t have them, and Debian determined through a formal vote that “GFDL-licensed works without unmodifiable sections are free [as in freedom]”.

I should also give credit to the Wikimedia Foundation (WMF), Richard Stallman of the FSF, and Lawrence Lessig, who worked together to make this possible.

For more on the Wikimedia license modification, you can see Wikimedia license FAQ, Lawrence Lessig’s post on GFDL 1.3, GFDL 1.3: Wikipedia’s exit permit, FDL 1.3 FAQ, and An open response to Chris Frey regarding GFDL 1.3.

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