GPL & "non profit use only"

[Luke Kenneth Casson Leighton]

On Mon, Mar 15, 2010 at 7:39 PM, Caroline Ford
<caroline.ford.work at googlemail.com> wrote:
> Also a link back requirement. Don't think you can qualify the GPL by adding
> additional or contradictory terms.

 ... because it's then not the GPL, is it?  so it's very clear-cut:
modify the GPL by adding to it, and it's no longer the GPL.

 however if the software's dual-licensed (vanilla GPL and
GPL+contradictory-GPL-modifications) then that would be okay, because
there would be a choice.  if no such choice is given, it's really
simple: it's no longer the GPL and no longer an "OSI-approved"
license.

l.