It occurred to me that Eric Haszlakiewicz wrote in gmane.os.netbsd.documentation:
> On Sun, May 22, 2005 at 04:28:30PM +0000, Martijn van Buul wrote:
>> Adding to this, Doxygen needs graphviz to be useful, and graphviz is
>> surrounded with problems.
>
> 	such as?

Do the google dance. For starters, "Hey, we'll grant you GPL-style rights for
our program, as long as you allow us BSD-style rights to patches". Far-fetched?

Maybe. pkgsrc claims it's different enough to require an entry in mk.conf
for it. I'm not sure we'd want Yet Another License, especially since there's
hardly any benefit.