Michael Beck (Team JEDI) wrote:
> I can be corrected by some of the MPL authors, but my understanding
> is that the <intent> of the MPL was similar to GPL, i.e. to ensure
> that "any derivative work under copyright law" should go back to the
> community (but without the viral effect of GPL) . Unfortunately,
> they didn't spell it outproperly in MPL, thus creating a room for
> misinterpretation.
I can't claim to speak for the authors of the MPL, but I think you are
treating as a bug in the MPL what was intended as a feature.
Both the MPL and GPL are copyleft licenses, in that they explicitly
require that (at least to some extent) people who create derivative
works of your original works are required by the license to offer their
contributions to those derivative works on the same terms as you offered
the original work.
The basic approach taken in the GPL is to specify that this copyleft
requirement applies to any work which would be considered a derivative
work under copyright law. This is a seeming simple and natural approach
to take; however IMO the problem in practice is that it can be unclear
how far the scope of the GPL extends, in the absence of any litigation
deciding this question. (And even litigation in one case would not
necessarily offer good guidance for other dissimilar cases.)
The basic approach taken in the MPL is to specify that the copyleft
requirement applies to any derivative work which bears a certain
specified relationship to the original work. This has the virtue that
the MPL provides language specifying how to determine in practice which
works have this specified relationship to the original work and which do
not. However the problem in theory is that the MPL copyleft requirement
wouldn't extend to cover all portions of some works which would clearly
be considered derivative works under most people's interpretation of
copyright law.
IMO these differences are due to different intents underlying the two
licenses. The intent of the GPL is to make maximum use of copyright law
to ensure that software based on free software is itself free, even if
that leads to potential legal risks for licensees who take GPLed
software and redistribute it in combinations where non-GPL software is
present. (The only way to totally eliminate such risk is to distribute
only GPLed software, which of course is exactly what RMS wants to
encourage.)
The intent of the MPL to allow licensees fairly wide scope to combine
MPLed software with nonMPLed software to produce new works, at the risk
of allowing some licensees to evade MPL requirements that require
sharing of source code for modifications to MPLed software.
Frank
--
Frank Hecker
[EMAIL PROTECTED]
