"And thus continue to wonder, is the hollow head/hook arrowhead really showing direction?"
I'm in agreement with the statement but find the way it is stated a bit confusing. For me, I always have my arrows (of any type) track the arc of the paper as it moves (see the second page of my posted "Andrea's Rose" diagrams for many examples of inward vs. outward arcs.) As for the "hook" on the fold behind arrow, it is always on the convex side (outside) of the curve... which amounts to the same thing as described in the original posting.
