What is a computational ontology?
Ontology identifies entities and their relations which are relevant for a certain domain of investigation. A typical example are ontologies in the medical domain.
Philosophical ontologies strive to capture the most general entity types, which are relevant for all scientific domains. The study of such ontologies has been started by Aristotle introducing ten 10 categories (= entity types).
If I consider "computational ontology" as dealing with ontologies in the domain of computer science, it would denote the methods how to create ontologies for modeling.
Since several decades the prototype of this kind of computational ontology is named "entity-relationship-modeling (ERM)". It deals with concepts like entity type, instance of an entity type, possible attributes of an entity type, lifecycle of entity types, relationship between entity types, cardinalities of such relationsships etc.
A follower of ERM is class-modeling, which enriches the ERM by the operations used to process a given entity. A formalization of class-modeling is the class-diagram of the Unified Modeling Language (UML).
For a general reference to ontology see http://ontology.buffalo.edu/