Subject: Re: license categories, was: I'm not supposed to use the ECL v2?
From: Arnoud Engelfriet <>
Date: Sat, 1 Dec 2007 21:39:10 +0100

John Cowan wrote:
> Arnoud Engelfriet scripsit:
> > The FSF's preferred statement says that the user has the option to
> > apply any later version of the GPL to the work. The work is GPLv2
> > until someone forks it and explicitly says he has elected the option
> > to apply GPLv3. Then that fork becomes GPLv3.
> Can you explain why this is not the same as explicit v2/v3 dual licensing?

The key is the phrase "at your option". That means that the user has
to do something (elect the option). 

The phrase allows free upgrading of the license to GPLv3. The work
isn't GPLv3 from day one, and does not become GPLv3 just because
the FSF publishes the text for GPLv3. A user has to take a version
of the work, somehow indicate he elects the GPLv3 option and make
that version available. Then that version becomes GPLv3.

> It's generally understood that if something is licensed under the GPL
> and the MPL, for example, that the licensee's powers are the union of
> those given by the GPL and by the MPL.  A fortiori, it would seem to me
> that given "v2 or later" software, you can do anything that either the
> GPLv2 or the GPLv3 allows.

What do you mean by "union"? I've never seen that before. Dual
licensing in my view means that as a licensee you have the choice
of which license you want to exercise. The licenses can be mutually
exclusive, e.g. MySQL's proprietary and GPL licenses, and then
their union would be empty. 


Arnoud Engelfriet, Dutch & European patent attorney - Speaking only for myself
Patents, copyright and IPR explained for techies:
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