The tool well in the middle allows clamping from the middle using standard F clamps rather than holdfasts/holddowns. It also allows bench hooks to be used reversed and hooked into the tool well for japanese saws.
The holes in the edge are to allow for the use of the Veritas panel clamp instead of a long clamp over the whole benchtop.
The bench is all knockdown. There are two end assemblies, the upper long dovetailed stringers, and the lower long shelf support stringers with knock-in wedges.