UML Class Diagram Notation
When it comes to system construction, a class diagram is the most widely used diagram. UML Class Diagrams is a type of static structure diagram that is used for general conceptual modeling of the systematics of the application. Such a diagram would illustrate the object-oriented view of a system . The object orientation of a system is indicated by a class diagram. It describes the structure of a system by showing the:
- classes of a system,
- attributes,
- objects,
- operations,
- and the relationships between classes.

Example 1. Control Package Class Diagram
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Video. How To Create UML Diagram (2min 25sec)
The following table represents notations that are used on the UML Class Diagrams:
Diagram element | Graphical presentation | Description |
Class |
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Class represents a set of objects that have the same structure, behavior, and relationships with objects of other classes. |
Attribute |
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Attribute is a typed value that defines the properties and behavior of the object. |
Operation |
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Operation is a function that can be applied to the objects of a given class. |
Responsibility |
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Responsibility is a contract which the class must conform. |
Interface |
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Interface is an abstract class that defines a set of operations that the object of the class associated with this interface provides to other objects. |
Association |
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Association is a relationship that connect two classes. |
Aggregation |
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Aggregation is an association with the relation between the whole and its parts, the relation when one class is a certain entity that includes the other entities as components. |
N-ary Association |
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N-ary association represents two or more aggregations. |
Composition |
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Composition is a strong variant of aggregation when parts cannot be separately of the whole. |
Generalization |
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Generalization ia an association between the more general classifier and the more special classifier. |
Inheritance | ![]() |
Inheritance is a relationship when a child object or class assumes all properties of his parent object or class. |
Realization |
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Realization is a relationship between interfaces and classes or components that realize them. |
Dependency |
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Dependency is a relationship when some changes of one element of the model can need the change of another dependent element. |
<< >> |
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Allows to define the properties of the dependency relationship between classes or classes and packages. |
{ } |
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Allows to indicate the additional properties of association. |
Multiplicity |
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Multiplicity shows the quantity of instances of one class that are linked to one instance of the other class. |
Package |
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Package groups the classes and other packages. |
Note |
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Note is a textual explication. |
Note connector |
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Note connector is a connection between the note and elements. |
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