Oskar Sigvardsson wrote:
Lets make an open source software analogy: if I make
my own
web-browser that is based on Firefox, I can't license that software in
anyway I want (whether it is to make it less free by making it closed
source or making it more free by using the BSD license) because the
GPL doesn't allow that kind of relicensing. Same thing with the GFDL,
you can't just change the rights of something that someone else wrote
unless that person specifically allowed it. You are only allowed to
make derivatives of someone else's work if you follow the rules, and
multi-licensing doesn't follow those rules (in my understanding,
anyway).
But if you were to create a new plugin for Firefox that's a separate
module of code that you wrote entirely by yourself, you could
multi-license just that one chunk of code under multiple licenses.
The idea with multi-licensing Wikipedia contributions is not that one
would go to an existing article, fix a few typos, and poof the article
is now multi-licensed. The idea is that an author could go and write a
brand new article, or add a new section to an existing article, and
_that_ material would be multi-licensed. An editor who subsequently
edits that material but who is not themselves multi-licensing would in
effect only be editing the version with the compatible license, so
subsequent revisions would in all likelihood be back under just the GFDL
again. But if someone really wanted to they could go back in the
article's history and dig out the "clean" multi-license material and
fork their own version under the other license.
Yeah, in the vast majority of cases this is a highly tedious and
probably unwieldy process. But it's not illegal and under some
circumstances it just might come in handy. Multi-licensing images is
probably the most useful thing since images tend to be monolithic units
that don't get edited much.