As E. Weddington wrote:
Now to the big problem: The original license file said that avr-libc was
a Modified BSD License (with the No Advertising clause). However the
"template" that it gave for new authors, only showed the original two
clauses of the BSD license.
The original BSD license had four clauses, where the `No advertising'
clause was #3, and later officially dropped. Individual *BSD
developers later on also dropped clause #4 ("name ... may not be used
to endorse"), which led to the two-clause template we had by now.
For those files where I hold the copyright, I don't mind whether it's
the 2-clause or 3-clause version. I agree we should settle for one of
both, and see to convert the remaining files (given author's
permission). It seems converting everything to the 3-clause version
is less work, so let's pick this one.