Indeed, we initially wanted to avoid the additional complexity introduced by allowing circular references, but our users demanded it. For any particular example in which circular references occur, it is always possible to create a new ontology, (e.g., sports-medicine) that contains the subset of the ontologies in the cycle. This is not a practical solution, however, because it may require the entire structure of the ontology library to be changed to add a single axiom. This would make it impossible to have a general-purpose library of ontological fragments that can be reused.
Users can change the default on a per-ontology basis.
The domain marked "Unk" accounts for all requests logged from anonymous connections. We log the requests according to the domain of the user's email address, not the current connection location.