Arc diagram: nodes as circles in a row or column, sized by their values and linked by arcs.

Chord diagram: nodes as arcs around a circle, linked by ribbons. A node’s arc shows its outgoing total, and a ribbon is as wide at each end as the flow out of that end, so a one-way link narrows to a point at its target.

Chord diagram for one-way flows: a node’s arc shows its incoming and outgoing totals together, and each link keeps its width all the way to the target, where it ends in an arrowhead.

Chord diagram with thin lines for links instead of ribbons. All nodes get arcs of the same size, whatever the link values.