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Re: GPL v2/v3 ?

On Wed, 5 Mar 2008 12:53:31 +0000 Diggory Hardy wrote:

> Hi (for lack of inspiration as to a more appropriate greeting),

Hi there!  :)

> I have since decided that the GPL is probably the most appropriate license to 
> use (although I am not entirely sure I like the fact it restricts derived 
> code from being distributed only under itself and not other licenses with the 
> same terms; however maybe that is necessary for what it achieves).

There is no other license with the same terms as the GNU GPL v2.
Hence, the GNU GPL v2 *must* impose that derivative works (if
distributed at all) be distributed under the terms of the GNU GPL v2,
or otherwise the copyleft mechanism would *not* be effective.

The same reasoning holds for the GNU GPL v3, except that,
unfortunately, its copyleft is already broken.  The very fact that the
GNU GPL v3 allows linking or combining with code released under the GNU
AfferoGPL v3 is one of the reasons why I consider its copyleft
mechanism to be broken.

I already expressed my thoughts on the GNU GPL v3 in the appropriate
thread[1], so I won't repeat them here in detail.

[1] http://lists.debian.org/debian-legal/2007/06/msg00266.html

> Anyway, the above points are moot since I've pretty-much decided to use the 
> GPL.


> However, I've been wondering whether license my project under the GPL v3, 
> or "v2 only", or "v2 or later".

That's a hard decision, but a very important one.

> I did came across this message: 
> http://lists.debian.org/debian-legal/2007/12/msg00114.html
> (specifically the note on v3).
> So, I was wondering if it makes the most sense to take a flexible approach and 
> release under "version 2 or later" of the GPL, albeit allowing problems with 
> either version of the license to be exploited, or be less flexible and 
> release under one version (possibly v2). I don't think compatibility with 
> other code's licenses is likely to be a problem either way.

In my opinion, the decision boils down to:

 o  if you want to enhance compatibility *and* you trust the FSF to
keep the promise that future versions of the GNU GPL will be "similar
in spirit to the present version"[2][3], then you may choose a "v2 or
later" approach

 o  if you want to enhance compatibility *and* you don't mind seeing
your copyleft more or less weakened (or even completely destroyed) by
successive versions of the GNU GPL, then you may choose a "v2 or later"

 o  if don't mind reducing compatibility *and* you want a strong and
certain copyleft (while not trusting the FSF to keep the spirit of the
GNU GPL v2 in successive versions), then you should choose a "v2 only"

[2] see GPLv2, section 9
[3] IMHO, the FSF has *already* broken that promise with the GNU GPL v3
[4] in this case, you may even consider choosing a simple permissive
non-copyleft license, such as the Expat/MIT one

Please always keep in mind that, with a "vX or later" approach, you are
effectively dual-licensing your work under yet unknown terms, as well
as under known ones.
On the other hand, the "vX only" approach makes it difficult to cure
yet undiscovered problems with vX in the long term.


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..................................................... Francesco Poli .
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