State Units are very similar to super units, but for state graphs instead of flow graphs. They allow you to nest a whole state graph into a single unit in a parent flow graph.
To create a blank state unit, choose Nesting > State Unit in the fuzzy finder. As usual, you can double-click the node or use the Edit Graph button from its inspector to open the nested graph. To create a state unit from a macro, you can either drag & drop the macro asset into your graph, or choose it from the Macros category in the fuzzy finder.
A state unit has two control input ports to indicate when to start and stop it, and two matching control output ports to specify what to do after.