James Stein describes “digraphs” in his book How Math Explains the World: A Guide to the Power of Numbers, from Car Repair to Modern Physics (HarperCollins 2008) at 3. According to Prof. Stein, “A digraph is a diagram with squares and arrows indicating the tasks to be done, the order in which they are to be done, and the time required.”
His example shows a series of boxes with arrows to indicate the flow of a process and how long each step should take. A digraph immediately helps figure out critical-path scheduling and moves Stein to a discussion of priority scheduling techniques in mathematics.
When a law department records and studies a process, it should incorporate the elements of a digraph. What needs to be done, in what sequence and with what handoffs, all set in the context of how long the different parts of the process should take. Some indicators of volume and number of people involved would enrich a digraph.