Most ontologies represent and support relationships among classes of meaning. Generalization is the relationship between a class and one or more refined versions of it. Each subclass inherits the features of its superclass, adding other features of its own. Generalization and inheritance are transitive across an arbitrary number of levels. They are also antisymmetric.
Aggregation is also transitive, as well as antisymmetric.
Some of the properties of the assembly class propagate to the component classes. Instantiation , which is the relationship between a class and each of the individuals that constitute it. Some of the other relationships that occur frequently in ontologies are owns , causes , and contains . A recent development for the World Wide Web is Meta Content Format . MCF is an open-format language for representing a wide range of ontological information about content.