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Terms starting with S



See also


  1. A specific sequence of actions that illustrates behaviors. A scenario can be used to illustrate an interaction or the execution of a Use Case instance.
  2. A sequence of operations carried out in some order to produce a known result. Can apply to Use Cases where it is the equivalent of a Sequence diagram, or to other objects to describe how they are used at run-time.


Schema (MOF)

In the context of the MOF, analogous to a Package that is a container of model elements. Schema corresponds to a MOF Package.

Package Metamodel


Reflects a new process or method invoked within the calling Lifeline's operation. It is a specification of a message.

Semantic Variation Point

A point of variation in the semantics of a metamodel. It provides an intentional degree of freedom for the interpretation of the metamodel semantics.

Send (A message)

The passing of a stimulus from a sender instance to a receiver instance.

Sender Receiver

Sender (Object)

The object passing a stimulus to a receiver object.


Sequence Diagram

A diagram that shows object interactions arranged in time sequence. In particular, it shows the objects participating in the interaction and the sequence of messages exchanged.

Unlike a Communication (Collaboration) diagram, a Sequence diagram includes time sequences but does not include object relationships. A Sequence diagram can exist in a generic form (describes all possible scenarios) and in an instance form (describes one actual scenario).

Sequence diagrams and Communication diagrams express similar information, but show it in different ways.

Communication Diagram Object Lifeline


The specification of an asynchronous stimulus communicated between instances. Signals can have parameters.


The name and parameters of a behavioral feature. A signature can include an optional returned parameter.

Single Inheritance

A semantic variation of Generalization in which a type can have only one supertype.

Multiple Inheritance

Single Valued (MOF)

A model element with multiplicity defined is single valued when its Multiplicity Type: upper attribute is set to 1.

The term single-valued does not pertain to the number of values held by, for example, an attribute or parameter at any point in time, since a single-valued attribute (for instance, with a multiplicity lower bound of zero) could have no value.



A declarative description of what something is or does.



A condition or situation during the life of an object during which it satisfies some condition, performs some activity, or waits for some event.

State Invariant

A condition applied to a Lifeline that must be fulfilled for the Lifeline to exist.


A behavior that specifies the sequences of States that an object or an interaction goes through during its life in response to events, together with its responses and actions.

StateMachine Diagram

A diagram that illustrates how an element, often a Class, can move between States classifying its behavior, according to transition triggers, constraining guards and other aspects of StateMachine diagrams that depict and explain movement and behavior.

State Chart

A diagram that shows a StateMachine.

Activity Graph State Machine

State Continuation

A symbol that serves two different purposes for Interaction diagrams - as State Invariants and as Continuations.

A State Invariant is a condition applied to a Lifeline that must be fulfilled for the Lifeline to exist.

A Continuation is used in seq and alt combined fragments to indicate the branches of continuation that an operand follows.

Combined Fragment

State Lifeline

A State Lifeline follows discrete transitions between States, which are defined along the y-axis of the timeline. Any transition has optional attributes of timing constraints, duration constraints and observations.

Static Classification

A semantic variation of Generalization in which an object can not change classifier.

Dynamic Classification Multiple Classification


A new type of modeling element that extends the semantics of the metamodel.

Stereotypes must be based on certain existing types or Classes in the metamodel. Tagged value

Stereotypes can extend the semantics, but not the structure of pre-existing types and Classes. Certain stereotypes are predefined in the UML, others can be user defined. Stereotypes are one of three extensibility mechanisms in UML.



The passing of information from one instance to another, such as raising a signal or invoking an operation. The receipt of a signal is normally considered an event.



A sequence of text characters. The details of string representation depend on implementation, and can include character sets that support international characters and graphics.

Structural Diagram

A diagram that depicts the structural elements composing a system or function.

These diagrams can reflect the static relationships of a structure, as do Class or Package diagrams, or run-time architectures, such as Object or Composite Structure diagrams.

Structural diagrams include Class diagrams, Composite Structure diagrams, Component diagrams, Deployment diagrams, Object diagrams and Package diagrams.

Structural Feature

A static feature of a model element, such as an attribute.

Structural Model Aspect

A model aspect that emphasizes the structure of the objects in a system, including their types, Classes, relationships, attributes and operations.

Subactivity State

A State in an activity graph that represents the execution of a non-atomic sequence of steps that has some duration.


In a Generalization relationship, the specialization of another Class; the superclass.

Child Generalization Parent Superclass

Submachine State

A State in a StateMachine that is equivalent to a composite State but its contents are described by another StateMachine.


A Package that is contained in another Package.


A State that is part of a composite State.

Composite State Concurrent Substate Disjoint Substate


A grouping of model elements that represents a behavioral unit in a physical system.

A subsystem offers interfaces and has operations. In addition, the model elements of a subsystem can be partitioned into specification and realization elements.

Package Physical System


In a Generalization relationship, the specialization of another type; the supertype.

Child Generalization Parent Supertype


In a Generalization relationship, the generalization of another Class; the subclass.

Generalization Subclass


In a Generalization relationship, the generalization of another type; the subtype.

Generalization Subtype


A classifier that provides services that can be invoked by others.



A partition on an Activity diagram for organizing the responsibilities for Actions. Swimlanes typically correspond to organizational units in a business model.



A State used for indicating that concurrent paths of a StateMachine are synchronized. After bringing the paths to a synch state, the emerging transition indicates unison.

Synchronize Code

The process of importing and exporting code changes to ensure the model and source code match.


A top-level subsystem in a model.

Physical System

System Boundary

An element used to delineate a particular part of the system.