The universal class of individuals. This is the root node of the ontology.
||ContentBearingPhysical||Any Object or Process that expresses content. This covers Objects that contain a Proposition, such as a book, as well as ManualSignLanguage, which may similarly contain a Proposition.|
| ||FinancialAsset||Any item of economic value owned by an individual or corporation, especially that which could be converted to cash. Examples are cash, securities, accounts receivable, inventory, office equipment, a house, a car, and other property.|
| ||Object||Corresponds roughly to the class of ordinary objects. Examples include normal physical objects, geographical regions, and locations of Processes, the complement of Objects in the Physical class. In a 4D ontology, an Object is something whose spatiotemporal extent is thought of as dividing into spatial parts roughly parallel to the time-axis.|
| ||PhysicalSystem||PhysicalSystem is the class of complex Physical things. A PhysicalSystem may have one or more corresponding abstract Graph representations.|
| ||Process||The class of things that happen and have temporal parts or stages. Examples include extended events like a football match or a race, actions like Pursuing and Reading, and biological processes. The formal definition is: anything that occurs in time but is not an Object. Note that a Process may have participants 'inside' it which are Objects, such as the players in a football match. In a 4D ontology, a Process is something whose spatiotemporal extent is thought of as dividing into temporal stages roughly perpendicular to the time-axis.|