Compatibility of the AFL with the GPL

[Brian Behlendorf]

All IMHO, and IANAL, coz I get burned every time I post here these days...

Despite these clauses being within the spirit of the GPL, they are
still additional restrictions on redistribution.

In the case of the trademark/names, one who creates a derivative work will
always have to worry that your interpretation of "endorse or promote" is
broader than anticipated.  For example, if a derivative work proudly and
loudly claimed its heritage, perhaps even named itself something similar,
there would always be the possibility that you would disagree, and the
right to redistribute would be revoked.  Sure, the GPL has other vague
clauses, but I just want to point out this is a clause that essentially
forms an additional restriction.

If instead the license simply *reminded* people that nothing gives them
the right to use the trademarks or good name of the original author, then
that wouldn't be an additional restriction.

As for the mutual patent termination clause:

> I'll leave for another thread any discussion about whether this is a
> good idea or a bad idea.  But how is it incompatible with the GPL?  The
> provision only applies to software licensed under the AFL and similar
> licenses, and it doesn't affect in any way software that is not licensed
> with this provision.

The whole point of "compatibility" between licenses is this: if you can
combine (not "mere aggregation", but linking, etc) software with license A
with software license B and legally redistribute it with license C, then
licenses A and B are compatible for some values of C.  If either A or B is
the GPL, then C *must* also be the GPL, and nothing more.  But, C must be
comprehensive and cover the license of the whole codebase; which means
your termination clause must be represented in license C, and that
prevents it from being the GPL.

Amateur set theorists will quickly see that the only licenses that are
compatible with the GPL are those whose terms and requirements are a
subset of those of the GPL.  That's always been my understanding.  The
MIT/X licenses are GPL-compatible because there is nothing they demand
from the end-user or redistributor that the GPL doesn't demand.

> ***Anyone*** is free to take software licensed under the AFL and
> re-license it under any license, including licenses not containing the
> Mutual Defense provision ["to use, copy, modify, merge, publish,
> perform, distribute and/or sell copies of the Original Work and
> derivative works thereof,..."].  In fact, the AFL permits anyone to
> freely relicense their derivative work software under the GPL.

But the license on the parts copied from the original work are still under
the AFL, right?  Which means any new license I put on it has to carry
forward the same terms, at least on that original code, unless I indemnify
those I give software to by meeting the terms on their behalf?

When we use third-party code in Apache, we're careful that the
requirements that code places are *not* more onerous than those of the
Apache license as well.

Surely you're not saying I can add some whitespace to the end of a .c
file, and put the entire codebase under the Apache license, for example.

	Brian
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