Spare Tire Well Plate

What is the brown plate in the bottom of the spare tire well there for on a 1992 lesabre? I found that on newer models it allows you to access the fuel pump, but there isn't anything to access underneath of it on the 92, and it does not even look as though it opens, though at first glance I really thought that it should.

I have seen these on almost every GM I have owned. I thought they were just a plug of some sort, maybe to drain water out of the wheel well if the trunk leaked.
On the newer cars you mention, the access plate for the fuel pump is not in the wheel well, it is ahead of the well in the floor of the trunk. At least that is where it is in my 2000 LeSabre and Lucerne.