Mandatory partitions include those annotation views that are always generated by PAS. Among the partitions, Domain partitions is a key view. Each program operates in a certain domain of the application, and the ontology of the application domain consists of domain concepts and their relations. The Domain partition explains the concepts behind the components, and therefore makes these components comprehensible to everbody who understand the domain. Reading domain partitions is usually the first step to the comprehesion of the code and the first step in the change, because change requests are formulated in domain terminology.
The Dependency partition is another important partition. Components of the program are dependent on other components. The dependencies are found by code analysis. However, programmers often must know what the dependencies mean (i.e. what role the supporting classes pay)