Converting/Splitting Code - Open to Closed

[Matthew C. Weigel]

On Mon, 12 Feb 2001, Eric Jacobs wrote:

> Brian DeSpain <bdespain at valinux.com>

> > Yes - but the previous versions licensed under the GPL remain GPLd and
> > development can continue on the code.
> 
> Can you explain why this is the case?

Because the license contains no provisions for revocation.  Thus, the
license can not be revoked, and thus people can continue to distribute the
old versions under the GPL.

> > That's exactly what would happen and that's why the GPL is there in the
> > first place. The copyright owner retains copyright, therefore can make
> > changes. You cannot retroactively change licenses under the GPL. People
> > retain their original rights under the GPL.
> 
> How can licensees retain their rights against the copyright owner's
> will? Is there something in the GPL that requires this?

Nah, it's not necessary.  Think of a license as a contract.  Can you sign a
contract with someone, and then, 6 months later, rewrite the contract? 
Maybe, *if* the contract says "I might rewrite this in six months, and
you're subject to my whims if I do."  Of course I'm not a lawyer, but I
think this is pretty clear.  As I mentioned elsewhere, look to the example
of the progressively closing ssh source, and how OpenSSH came about: they
took the last GPL'd version and went from there.
-- 
 Matthew Weigel
 Research Systems Programmer
 weigel+ at pitt.edu