What is Catering Minimum in terms of $$$ meaning?

I'm talking to a venue and they list a $4000 event time slot and then a $4000 catering minimum. I'm trying to determine if that means in order to have catering, we must spend at least $4000 with them on the event? Or on the catering itself? Most of the offerings run about $35/per person, and I have a smallish wedding planned, about 50 people, which if you do the math is about half that minimum number. It's still a pretty good deal, I think. I'm just not 100% on the terminology.