support requirement

[bruce at perens.com]

From: VAB <alexb at ufl.edu>
> Are they allowed to pick up code from the community (GPL'd code)
> and include it in PHP from which it can then propagate to commercial
> forks of PHP?

No. They would have to contact the copyright holders of that code and
arrange to re-license it first. In the case of the GPL-ed software that
you write, you are the copyright holder, so they'd have to ask _you_.

> I've seen many other people do dual licensing with supposedly "GPL"
> compatible licenses such as the artistic license as well.

Right. But it's always the copyright holder who makes that decision.
Nobody else has the right to add a new license to a copyrighted work
without first making an arrangement with the copyright holder.

> Am I mistaken and this type of dual licensing is only possible 
> with an original work which contains no previously GPL'd code?

You're just a bit confused. If I put the GPL on my own copyrighted work, I
can put any number of other licenses on it concurrently because as the
copyright holder that is my decision, and solely my decision, to make. I can't
do that to anyone else's copyrighted work without making some sort of
arrangement with them.

> but I have a hard time believing that all of the
> code dual licensed out there is original code.

Some people contribute modifications to dual-licensed code, with
the clear understanding that the modifications will be distributed
under both licenses. As the copyright holder of the modification, they
have the right to make that decision.

Some people (FSF is one example) will not accept modifications unless you
sign the copyright over to them, in which case they get to make all
decisions about licensing and can dual license that modification if they wish.
All LGPL-ed work is actually dual-licensed LGPL and GPL, because that's part
of the terms of the LGPL.

Some licenses (the NPL, for example) explicitly require that you let the
"original contributor" (Netscape, in that case) distribute modifications
under other licenses, thus they have the right to dual-license all
modifications.

> Is there a way I can prevent this from happening to my software?

There's no need. If you use the GPL, and you retain your copyright to your
software, and you do not explicitly dual-license it, nobody else can dual
license it without your permission.

> Is it legally possible for me to write a license that restricts
> any one at any time in the future from dual licensing any of the
> code that I write and taking it away from the community?

The GPL already does that. Only _you_ have the right to dual-license your
own work if it's under the GPL.

I hope this clears up your question. Please don't hesitate to write if there's
any more light I can shed on this.

	Thanks

	Bruce