I've put communication holes at the top, on the theory that there is less
room up there for moving from frame-to-frame, and on natural comb that's
where you find them, anyway.  I'd be interested in the reason why someone
would think they need to be at the bottom, where the frames don't generally
meet, as they do at the top.  Seems redundant.
 
Jane B.
In unseasonably warm San Jose, California...