> I've never heard the term "FSF-valid", but the FSF considers the BSD > license to be both free and GPL-compatible.
The original BSD license had an attribution clause that said you had to include a statement of copyright in any advertising that mentioned the software. The GPL doesn't allow any license restrictions other than its own, so this obviously wasn't GPL-compatible. Why they decided that this particular clause was so terrible that they had to wage a campaign to get CSRG to change it, I have never figured out. The straw man they advanced to explain it still doesn't make sense to me, and they don't seem worried about people trademarking terms like Linux, which has the same effect...
