Redistributions must retain this list of conditions

John Cowan cowan at
Sun Nov 11 06:57:30 UTC 2001

Paul Guyot scripsit:

> You seem to consider on this list that one can re-license anything 
> under BSD under the GPL -- well, a lot of people seems to consider 
> this, including the FSF [...].

"Relicense" is a misleading expression, and should probably be
avoided, as it leads to wifty thinking.

What is meant is that program A, licensed under BSD, can be
combined with program B, licensed under GPL, to produce a new
work A+B licensed under the GPL, because the resulting work
meets both BSD and GPL criteria for derivative works.

On the other hand, if you have program C, licensed under the MPL,
you cannot produce a derivative work B+C, because the requirements
of the MPL and the GPL with respect to derivative works conflict.

> Now, the FSF says (and I think I read it here as well) that the 
> original BSD isn't compatible with the GPL because of the advertising 
> clause. I understand the FSF's argument against this clause 
> (, and I found it funny myself 
> when I saw that many sentences in NetBSD documentation.
> However, I can't see what makes it incompatible with the GPL. 

Because the GPL requires that no restrictions be placed on derivative
works except those of the GPL itself.  The old BSD license did place
such a restriction on derivative works: the source needed to be mentioned
in the documentation.  As such, work D licensed under old BSD could
not be combined with B to form B+D.

> Actually, I think I see but I can't see how removing this clause 
> makes it compatible with the GPL.

The new BSD doesn't impose requirements over and above the GPL's.

John Cowan               cowan at
Please leave your values        |       Check your assumptions.  In fact,
   at the front desk.           |          check your assumptions at the door.
     --sign in Paris hotel      |            --Miles Vorkosigan
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