What Are Bounding Boxes and How Do I edit them?

[Atrocities]

I am in the process of setting up firing arcs for a new ship set and I have discovered that the shipset viewer has this options call Bounding Boxes.

I noticed that the ships I am working on have these boxes but they do not surround the ship like they do in other sets. The bounding boxes are oriented in a top down direct and not level with the ship. They share a common center point, but while the ships face say N and S, the bounding boxes face Up and Down. Very odd.

So does any one know anything about bounding boxes, what they are for, and how to adjust them?