What is this hole in the engine between the 2nd and 3rd spark plug
 

While replacing my spark plugs, I saw there is a hole between the 2nd and 3rd spark plugs and it probably takes a screw that is missing. (see pic below)
https://cimg8.ibsrv.net/gimg/www.maz...63d30a1f34.jpg

The pic is taken after removing the second coil. But that hole in the metal is not the hole for the second spark plug. It is between the 2nd and 3rd plugs (this pic is taken from about 45 degree angle to the vertical).
Any idea what is that for? Last year, the Mazda dealership replaced the valve cover gasket, and I wonder if they missed putting a screw in.

This is 2012 Mazda 3, with non-skyactive engine, 2.0L.

Did you ever figure this out? I saw the same thing and had the same question.

@chuvisco On another forum, this is what someone replied:
This is the link to that forum thread.

Thanks!