[ltp] What's this screw for?

[Ignacio Fernández Galván]

Hi,

I bought a ThinkPad R51 (1829-R6G) and it came with several "accessories"  
(cables, trackpoint caps...). One of these things was a small screw with a  
"six-sided hole in its head" (I'm sure there's a name for that, but I  
don't know it). Looking at the bottom side of the laptop, I found a hole  
where the screw apparently fits, it's near the "lever" for extracting the  
ultrabay (DVD drive). But I don't know what's the job of this screw, there  
doesn't seem to be any difference when the screw is in or out. Does anyone  
know what's it for? Should I leave it in or out?

Thanks