The universal class of individuals. This is the root node of the ontology.
||Attribute||Qualities which we cannot or choose not to reify into subclasses of.|
| ||List||Every List is a particular ordered n-tuple of items. Generally speaking, Lists are created by means of the ListFn Function, which takes any number of items as arguments and returns a List with the items in the same order. Anything, including other Lists, may be an item in a List. Note too that Lists are extensional - two lists that have the same items in the same order are identical. Note too that a List may contain no items. In that case, the List is the NullList.|
| ||ProcessTask||A function to be performed.|
| ||Proposition||Propositions are Abstract entities that express a complete thought or a set of such thoughts. As an example, the formula '(instance Yojo Cat)' expresses the Proposition that the entity named Yojo is an element of the Class of Cats. Note that propositions are not restricted to the content expressed by individual sentences of a Language. They may encompass the content expressed by theories, books, and even whole libraries. It is important to distinguish Propositions from the ContentBearingObjects that express them. A Proposition is a piece of information, e.g. that the cat is on the mat, but a ContentBearingObject is an Object that represents this information. A Proposition is an abstraction that may have multiple representations: strings, sounds, icons, etc. For example, the Proposition that the cat is on the mat is represented here as a string of graphical characters displayed on a monitor and/or printed on paper, but it can be represented by a sequence of sounds or by some non-latin alphabet or by some cryptographic form.|
| ||Quantity||Any specification of how many or how much of something there is. Accordingly, there are two subclasses of Quantity: Number (how many) and PhysicalQuantity (how much).|
| ||Relation||The Class of relations. There are two kinds of Relation: Predicate and Function. Predicates and Functions both denote sets of ordered n-tuples. The difference between these two Classes is that Predicates cover formula-forming operators, while Functions cover term-forming operators. |
| ||SetOrClass||The SetOrClass of Sets and Classes, i.e. any instance of Abstract that has elements or instances.|