What goes on the bottom of the lid on the middle compartment

The slotted compartment is for travel size tissue package I believe. Nobody seems to know what the clip is for. I guess it's for a pen and notebook. I've looked a dozens of different arrangements and can't find a convincing answer, it's too big for a pen (by itself), tire gauge (and it's off to the side?), glasses (they fall out).

Little slide out tray, a flat hard piece of plastic they say it supposed to be used for someone to have something flat to write on in the car. Back in the day weveryone called them dope traysto break up some smoke on it