Re: A short licence check
On Sun, Aug 22, 2004 at 04:29:29PM -0400, Raul Miller wrote:
> The non-GPL copyleft license I've most frequently encountered is the LGPL.
> If A is GPLed and B is LGPLed, it's legal to produce C which is derived
> from A and B without getting any further permissions. [B isn't the GPL,
> but its terms do not impose anything which is more restrictive than the
> GPL's terms.]
It does, if you ignore LGPL#3. The LGPL, like the GPL, has a "no additional
restrictions" clause (LGPL#10); you can't add restrictions or take away
permissions, just as with the GPL.
The LGPL then gives you permission to link in special ways (dynamic
linking, object files, and so on). Thus, LGPL#10 says "you may not remove
the freedom to [dynamically link without providing source]". The GPL
doesn't give this permission.
I believe that's the basic purpose of LGPL#3--to make it GPL-compatible.
(I'm considering the LGPL without #3 because you separated that case
below, so I'm assuming you were referring to the LGPL without it above.)
> Thus, I believe that your "I can't produce" assertion can not always be
> the case.
>
> That said, people licensing their code under the LGPL often also license
> it under the GPL so that people can drop the LGPL license if they wish.
> Thus, even if the LGPL were somehow incompatible with the GPL, there
> would still be examples of B where you wouldn't need further permissions
> to derive a work from A and B.
They always do so; if you don't give that permission, it's not the LGPL.
The requirement is built into the LGPL (#3), and LGPL#10 bolts it in
(with the "these permissions must be preserved" clause).
--
Glenn Maynard
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