The context of an object model consists of the entity being modelled, considered as a black box, and its environment, where the environment consists of other entities that are known to or that interact with the entity being modelled. This serves to describe the environment and the interfaces as well as other external relationships.
The environment of a type consists of conceptual entities, called roles, relations and connections. The environment of an instance consists of actual entities playing the roles.
By associating property models with the context it is possible to specify the external properties that the object provides as well as the properties it requires from its environment.