Some hubs have bevelling (I'd call it countersinking, but as you'll see later the spoke heads do NOT go on the bevelled side) if you look at any side of any flange on the hub. The diagram at the left is an example.



Some hubs have holes bevelled on both sides, so that it makes no difference which side you stick the spoke in. But others have holes bevelled on one side only, with bevelling direction alternating on the flange. On the diagram to the left, the holes that don't appear bevelled are bevelled on the other side of the flange.



The purpose of the bevel is NOT to house the spoke head. Instead, the purpose is to match the curve of the spoke coming out of its head, so that the spoke is not continuously cut by a sharp right angle. When holes have bevels only one one side, ALWAYS stick spokes into the non-bevelled side.