This concept relates to the relationships betwen behaviors.
A Process Hierarchy defines which ordering of events and which prirorities exist in relationships between them. This is discussed in Cultivating Flows at length where we (Herman Wagter and Jean Russell) propose that rather than having a social hierarchy where some individual has decision making authority over others, that we can create and count on processes that we align on.
Consider the example of traffic intersections. People are moving about and cross paths. At some threshold of crossing paths and some threshold of speed, we find it safer and more effective to have agreements about who goes where when. We can use traffic lights which everyone agrees to follow, but they are centrally managed - the city decides the timing of the lights. Even if nobody is around, you still must stop for the light. A process hierarchy approach would be a roundabout, with the simple protocol that you always yeild to existing traffic in the circle. This method puts agency and decision making back into the drivers hands while also allowing for an increase in volume of the flow.