[tor-relays] Minimum port 80 and 443 exit policy

Hey all, I was wondering what the minimum exit policy was (wrt port 80 and 443) for a Tor exit relay. I cant find any documentation about the minimum exit policy. Is it possible to have an exit relay exit only to a /16 or a /8 on port 80 and 443? I've tried having an exit policy that allows exiting to just a /16 on port 80 and 443 and it seems to not stick. Best