combining software under different licenses

[Richard Fontana]

On Sun, 30 Aug 2009 09:29:15 +0100
David Woolley <forums at david-woolley.me.uk> wrote:

> The GPL does not require improvements to be shared with the original 
> author.  It definitely doesn't require this in the strong sense that
> the original author gets the same rights as the improver, and it
> doesn't require it in the weaker sense, that the original author gets
> a copy when other people receive one.
> 
> All it requires is that anyone who receives a binary compiled from
> that improved version, has the right to receive a copy of the
> corresponding source.  (It also requires them to be able to obtain
> copies of the sources for binaries produced from unmodified
> sources.)  Those sources must not have any more licensing
> restrictions than the included in the GPL, and must not have any less
> rights. 

There are some other licenses that actually affirmatively require the
licensee to share improvements with upstream licensors. I understand
the FSF's position (based on discussions between the FSF and the Fedora
Project) to be that requirements to provide otherwise non-distributed
changes upstream are non-free, as are requirements to provide
already-distributed changes where the upstream licensor has not first
specifically requested them.  Requirements to provide changes upstream
where those changes have already been distributed downstream, upon
upstream's request, may be free but are GPL-incompatible as "further
restrictions". 

This FSF position partially explains one of the cases in which the FSF
has declared non-free a license that has been certified as 'Open
Source' by the OSI, the Reciprocal Public License.  

- RF