I am about to install some wall cabinets. The instructions say to
"Pre-drill the cabinet (through top and bottom rail) to line up with
the wall studs." What the heck are the top and bottom rail? On the
base cabinets there is a piece of wood at the top which I guess is the
hanging rail which would be screwed to the wall. Since the entire back
of the wall cabinets are the same wood I guess it doesn't matter where
you screw them in. How can you hide the unsightly screw heads?

Thanks for any advice.