The Prozima Planning Engine v0.4 has a fully documented API, however it's always useful to see the classes described graphically. Below are two UML diagrams describing the public API provided by the Planning Engine library. The first is a class diagram which describes the most important class provided by the API. It does not list every subclass of Command as this would clutter the diagram too much. (click the diagram to enlarge)

Secondly, here is a simple sequence diagram which describes the process of passing a Command to the API using the invoke() method.