(this post has moved to http://bb-9.blogspot.com)
The builders have "standardized" on a system of labeling the panels on bb8 so that we can discuss them. As there are 6 panels, I suggested numbering them like the faces of a die, and this is what we ended up with.
BB-8 Hatch Nomenclature - Panel image courtesy of TinyP
There's also a "top", "bottom", etc. system that I find confusing since he is, after all, a sphere, where each of those could become any other....