I (Glossary)

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A definition of how something is constructed or computed. For example, a class is an implementation of a type, a method is an implementation of an operation.

implementation class

A stereotyped class that specifies the implementation of a class in some programming language (eg., C++, Smalltalk, Java) in which an instance can not have more than one class. An Implementation class is said to realize a type if it provides all of the operations defined for the type with the same behavior as specified for the type's operations.

See also: type

implementation inheritance

The inheritance of the implementation of a more general element. Includes inheritance of the interface.

Contrast: interface inheritance


In the context of packages, a dependency that shows the packages whose classes can be referenced within a given package (including packages recursively embedded within it).

Contrast: export


A relationship from a base use case to an inclusion use case, specifying how the behavior for the base use case contains the behavior of the inclusion use case. The behavior is included at the location which is defined in the base use case. The base use case depends on performing the behavior of the inclusion use case, but not on its structure (ie., attributes or operations).

See also: extend


The mechanism by which more specific elements incorporate structure and behavior of more general elements related by behavior.

See also: generalization

initial state

A pseudo-state used to denote the default state of a composite state; there can be one initial vertex in each region of the composite state.

interaction diagrams

A group of diagrams including Timing Diagrams, Sequence Diagrams, Interaction Overview Diagrams and Communication Diagrams.


An entity that has a unique identity, a set of operations that can be applied to it, and a state that stores the effects of the operations.

See also: object


A specification of how stimuli are sent between instances to perform a specific task. The interaction is defined in the context of a collaboration.

See also: collaboration

interaction diagram

A generic term that applies to several types of diagrams that emphasize object interactions. These include collaboration diagrams and sequence diagrams.

interaction occurrence

A reference to an existing interaction element. Interaction occurrences are visually represented by a frame, with "ref" in the frame's title space. The diagram name is indicated in the frame contents.

interaction overview diagram

A diagram that visualizes the cooperation between other interaction diagrams to illustrate a control flow serving an encompassing purpose. As interaction overview diagrams are a variant of activity diagrams, most of the diagram notation is similar, as is the process in constructing the diagram.


A named set of operations that characterize the behavior of an element.

interface inheritance

The inheritance of the interface of a more general element. Does not include inheritance of the implementation.

Contrast: implementation inheritance

internal transition

A transition signifying a response to an event without changing the state of an object.

interrupt flow

An Enterprise Architect-defined Toolbox Icon used to define the exception handler and interruptible activity region concepts.