Giving credit for original author with dual GPL / MIT license

Question

I have just made some changes to a jQuery ui widget and I would like to release them.

I'm not concerned about releasing the changes under the same license, but I would like to know how I should indicate copyright for my changes?

The original copyright statement (below) only refers to an authors.txt file.

/*
* jQuery UI Draggable 1.7.2
*
* Copyright (c) 2009 AUTHORS.txt (http://jqueryui.com/about)
* Dual licensed under the MIT (MIT-LICENSE.txt)
* and GPL (GPL-LICENSE.txt) licenses.
*
* http://docs.jquery.com/UI/Draggables
*
* Depends:
* ui.core.js
*/

Am I also allowed to change the name? Then how does that relate to the original authors?

I don't want to tread on any toes and I want to avoid doing this incorrectly. I would appreciate any advice.

Thanks.

Answer 1

Not an expert on what the MIT license will offer you if you choose to go with their GPL license then I'm pretty sure so long as you release your changes with a GPL licensing option for others you can do whatever you want with it. You can change the name as much as you like, including the name, so long as you release it under a GPL (Or GPL-compatible) license.

I'm not sure if GPL explicitly requires attribution, but either way common courtesy says you should at least leave something mentioning where you got the starting code from.

The MIT license may offer you more rights than this, but I don't know much about that one (Though to be honest the GPL requirements aren't too onerous typically)

Answer 2

The definitive licences can be found on the OSI site (http://ideas.opensource.org/). I'd look at the FAQ there to see if there are answers to dual licence problems (http://ideas.opensource.org/wiki/help).

The MIT licence is "permissive" meaning roughly that the authors insist on very little other than acknowledgement. The GPL is "copyleft" which places responsibilities on you to distribute your modifications under the same licence. MIT and GPL have different philosophies.

Wikipedia addresses dual licences. The article should be read in full but an excerpt:

Since in most cases, only the copyright holder can change the licensing terms of a software, multi licensing is mostly used by companies that wholly own the software which they are licensing. Confusion may arise when a person outside the company creates additional source code, using the less restrictive license. Because the company with the official code is not the copyright holder of the additional code, they may not legally include this new work in their more restrictively licensed version. Companies may demand outside developers agree to a contributor license agreement, before accepting their work in the official codebase and source code repositories.[3]

Multi licensing is used by the copyright holders of some free software packages advertising their willingness to distribute using both a copyleft free software license and a non-free software license. The latter license typically offers users the software as proprietary software or offers third parties the source code without copyleft provisions. Copyright holders are exercising the monopoly they're provided under copyright in this scenario, but also use multi licensing to discriminate the rights and freedoms different recipients receive.

Such licensing allows the holder to offer customizations and early releases, generate other derivative works or grant rights to third parties to redistribute proprietary versions all while offering everyone a free version of the software. Sharing the package as copyleft free software can benefit the copyright holder by receiving contributions from users and hackers of the free software community. These contributions can be the support of a dedicated user community, word of mouth marketing or modifications that are made available as stipulated by a copyleft license. However, a copyright holder's commitment to elude copyleft provisions and advertise proprietary redistributions risks losing confidence and support from free software users.