The core of the system does nothing more then manipulating the data. It knows nothing about the meaning of it.
Extra power and usefulness comes from the extensions (and agents, and whatever you will call them). They have knowledge about how to use, in particular the relations, to get from one notion to another and navigate through the network or to do something particular.
Example: one of the extensions knows how to build a genealogical tree and how to generate web pages for them. For being capable of getting the right information out of the knowledge base, he needs only a little information:
As all there is in Notion System is reduced to relations and notions, every agent (or extension) only needs the answer on generally only a few of similar questions.
Once the results returned by Notion System, what he is supposed to do with is his own specialty.