Here is the place where I found out about this, though I sure didn't see this at home, but then I wasn't trying this link. It sure wasn't in the manual. Perhaps it wasn't meant to be in this winSPWW2 version?
http://linetap.com/www/drg/OPfire.htm
When I get home, if I follow what they have here and use "filter" on the ranging then that's obviously where it would be in the game if uesable by the human players.