How to: Visualize a Collection Association (Class Designer)
Properties and fields that are collections of other types can be displayed on the class diagram as a collection association. Unlike a regular association, which displays a field or property as a line linking the owning class to the field's type, a collection association is displayed as a line linking the owning class to the collected type.
To create a collection association
In code, create a property or field whose type is itself a strongly-typed collection.
In the class diagram, expand the class so that properties and fields are shown.
In the class, right-click the field or property and choose Show as Collection Association.
The property or field is shown as an association line linking to the collected type.