I think it's like a rect, but more flexible in how it's shaped since you can add multiple rects, specific locations (well, a 32x32 square at a specific location)
Regions are made up of individual 32x32 (if I remember correctly) 'cells', being just a small block of space. Using RegionAddCell() (once again, off the top of my head) you can add a single cell to a region, generally used in a loop with a formula. Similar functions exist for adding a rect to a region.
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.