| For documentation purposes, it is possible to display a directional arrow on arcs that indicates flow. This property can be changed with the Toggle Directionality command (in menu Edit / Arc). It may also be controlled by checking the appropriate box in the Object Properties... dialog.

The arrow always runs from the tail of the arc to the head of the arc unless you reverse the arc (with the Reverse command in menu Edit / Arc, or by checking the "Reverse head and tail" box in the Object Properties... dialog). If the head of the arc is "skipped" (with the Toggle Head-Skip command or by checking the appropriate box in the Object Properties... dialog), then the arrow head is not drawn.