For INN you would define them in your /usr/lib/news/newsfeeds.
This would feed node 33 in net 125 the newsgroups defined as
fido.NET-125 and fido.COOP only.
This would feed node 5109 in net 125 the newsgroups defined as
fido.* except for fido.NET-125 and fido.COOP.
I've found it works best if you start out with the areas you want to
send then followed by the areas you don't want to send. Your mileage
WARNING: It's very important you remember to exclude all other
newsgroups by explisitly stating so with a preceeding "!" symbol
("!fido.*,!local.*!junk") otherwise the node is likely to get the intire
backbone and then some sent to him. <grin>