Called it 'group_tbl' and did a special-case check for it. Turned out I had it well-enough modularized already that I only had to put the check in one place. (Yay me!)
Thing is, the guy is a c++ wizard, and the only one here who can work with the HP3000's. (Our main work right now, BTW, is to port everything off them and get rid of them.) He still thinks the right way to do efficient data access is flat files. And seems to believe if something is not how he already does it, it can't be right.
PS: Shhh, don't tell anyone (especially not my wife) but I'm already checking the classifieds again.