Lines 85 & 86 of FreeBSD-5.2.1 /etc/defaults rc.conf says:
ipfilter_rules="/etc/ipf.rules" # rules definition file for ipfilter, see
# /usr/src/contrib/ipfilter/rules for examples
I see no examples there but find many under /usr/share/examples/ipfilter
Possibly applies to 4.9 too.
Thanks again for great documentation.
--
John.