🚀 go-pugleaf

I would like to know how to limit nnmaster's article collection to a
(relatively) small number of hierarchies. I get my feed from an NNTP
server with a very comprehensive list of groups, which is nice. However,
my database is already more than 50 Mb (although "nnadmin s" reports it
to be only 25 Mb), and constantly growing. Is there an easy way to tell
nnmaster to collect articles from (for example) alt., bit., comp., news.,
rec., soc., and talk., and to ignore all other groups entirely?
I tried the following:

	nnmaster -l -r -C alt bit comp news rec soc talk

but it is still adding groups like chile.revistas.informatica and
uk.bcs.announce to my $MASTER/GROUPS file.

Also, there are currently about 2000 groups in my GROUPS file that I'd
rather ignore entirely...is there an easy way to remove them without
editing the file line by line or re-initializing the database?
Thanks in advance,

Gerald