On 16-Apr-2007, lolo wrote:
Multilicensing: 1-Could i license something under 2 diferent copyleft compatible licenses? 1.1-Could i license something under 2 copyleft uncompatible licenses? 1.1.1-If so, Could i also add a third one to the same document? 1.1.2-Could i also license it with a fourth free, non-copyleft, gpl compatible one?
The copyright holder has certain freedoms reserved under copyright law, and has the ability to allow others to exercise these freedoms on her own terms. These freedoms *are* the license (look up the meanings of the word "license" and you'll see it is somewhat similar), and the terms are those stipulated when the recipient gets the work.
Thus, if you have sole copyright in a work, you can grant any particular people you choose any of your rights, on any terms you want, as many different times as you like.
If you grant a license to one person, you can grant a completely different license to another person. You can even grant two different licenses to the *same* person, and then that person has been given two different sets of things they can do, under two different sets of terms -- i.e. more freedom.
When that person decides they want to perform some act covered by copyright, they are dealing with a single work by a single copyright holder, and they only need one permission to do so -- they can *choose* which of the licenses they will exercise.
The situation is different if you're *combining* works under different licenses, because then you're not the sole copyright holder. You, *and* the people whom you received pieces of the work from, are all join copyright holders, and the license under which you received each piece of the work must be followed.
When you distribute a work that *you* received as a combination of different works under different licenses, they must all be satisfied as far as distribution is concerned. If you are allowed (by all of the licenses you received to the work) to re-license the work, you can do so, and the recipient gets it under that license. If, on the other hand, you may redistribute under one particular license, then that's your only option for performing the act of redistribution.
Re-licensing: Project 'a' was GPL when it was 1.1, now is 2.2 and has changed into LGPL, ok? Project 'b' was GFDL and now hasn't got any license displayed, ok? Project 'c' was GFDL and they changed the license banner into another copyleft uncompatible one, ok?
You don't state whether these are cases of the work being distributed by the copyright holder, or re-distributed verbatim by a recipient, or re-distributed as a modified work by a recipient.