What's missing here?
 

First post about my first resto mid Camaro. It's a 69 Z28 and I'm fixing the little annoying things. Can someone tell me what is supposed to cover this hole above the rear package tray?

Wow! That's a new one on me... as I've never seen that.
My 69 doesn't have one.

I've never seen that either. Not the rear defroster option, as that only had a rectangle vent on the deck between the speakers. Perhaps someone once added a third brake light, it's in the right place for that. Do the holes look like factory, or an end user drilled hole?

They look factory punched

Nothing on the RPO list that I can see involves that rear window trim. I'd be curious enough to remove the piece and see if there are any GM part numbers on the back; 39XXXXX, or other non GM name or numbers. Possibly an aftermarket part (still thinking 3rd brake light)?