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Terms starting with O



See also


An entity with a well-defined boundary and identity that encapsulates state and behavior. State is represented by attributes and relationships, behavior is represented by operations, methods and StateMachines. An Object is an instance of a Class.

Class Instance

Object Diagram

A diagram that encompasses objects and their relationships at a point in time. An Object diagram can be considered as a special case of a Class diagram or Communication diagram.

Class Diagram Communication Diagram

Object Flow

A sub type of the State flow or transition. It implies the passing of an object instance between elements at run-time.

Object Flow State

A state in an Activity graph that represents the passing of an object from the output of actions in one State to the input of actions in another State.

Object Lifeline

A line in a Sequence diagram that represents the existence of an object over a period of time.

Sequence Diagram

Object Management Group (OMG)

The standards body responsible for the UML specification and management.


A relationship that indicates that a Collaboration represents a classifier. An Occurrence connector is drawn from the collaboration to the classifier.


A service that can be requested from an object to effect behavior. An operation has a signature, which could restrict the actual parameters that are possible.