Editing Class (computer programming) (section)

===Modeling===

In [[object-oriented analysis and design|object-oriented analysis]] and in [[Unified Modelling Language]] (UML), an [[Association (object-oriented programming)|association]] between two classes represents a collaboration between the classes or their corresponding instances. Associations have direction; for example, a bi-directional association between two classes indicates that both of the classes are aware of their relationship.<ref name="ibmuml">{{cite web| url=http://www.ibm.com/developerworks/rational/library/content/RationalEdge/sep04/bell/|title=UML Basics: The class diagram|last=Bell|first=Donald|work=developer Works|publisher=IBM|access-date=2012-05-02}}</ref> Associations may be labeled according to their name or purpose.{{sfn|Booch|1994|p=179}}

An association role is given end of an association and describes the role of the corresponding class. For example, a "subscriber" role describes the way instances of the class "Person" participate in a "subscribes-to" association with the class "Magazine". Also, a "Magazine" has the "subscribed magazine" role in the same association. Association role multiplicity describes how many instances correspond to each instance of the other class of the association. Common multiplicities are "0..1", "1..1", "1..*" and "0..*", where the "*" specifies any number of instances.<ref name=ibmuml/>