An anonymous union is an unnamed class used to represent a set of classes that can be used as a type of a property. An anonymous union class always implies a complete subclass generalization. (See Complete Subclasses.)
The following diagram states that an instance of a Person may have a value of type Cat or Dog for the cares for property. The diagram also states that an instance of a Cat or a Dog may have a value of type Person for the cared for by property.
Figure 1: An anonymous union class.
In an ontology, if anonymous union, with same classes within the union, is used in multiple places, the Concept Modeler can distinguish it when importing the ontology. In other words, if the anonymous union has the same union members, the Concept Modeler will identify it as the same anonymous union.