> NetBSD 3.0 includes PF 3.6 (PF from OpenBSD 3.6) plus some patches from 
> the OPENBSD_3_6 branch.
> 
> I made the assumption (for book published) last summer that NetBSD 4.0 
> includes PF from OpenBSD 3.7 with patches from the OPENBSD_3_7 branch.
> 
> It looks like 3.1 and 4.0 are mostly the same from a quick look.

I worded that wrong. I meant to say: It looks like 3.1 and upcoming 4.0 
are mostly the same as 3.0 and 4.0 as I assumed last summer, respectively, 
from a quick look. (3.0/3.1 and 4.0 are not the same.)