Use an n-ary association class in a static structure diagram to add attributes, operations, and other properties to an association. Drawn as a class attached by a dashed line to an association, an association class is actually a single modeling element. The element has a single name that can appear on the association, in the class, or in both places. The association ends can have the usual adornments.
Name an N-ary Association Class shape and add adornments to its ends
Open the element's UML Properties dialog box by double-clicking the icon that represents the element in the tree view or the shape that represents the element in a diagram.
Control which property values display on a shape in a diagram by right-clicking the shape, and then clicking Shape Display Options. In the UML Shape Display Options dialog box, select and clear options to display or hide property values.
Choose the number of n-ary association class ends
Double-click the N-ary Association Class shape, and then, under End Count, choose the number of ends you want.
Reposition the class in relation to the association
Drag the control handle in the center of the class.
Hide the attributes or operations sections of an association class
Right-click the shape, click Shape Display Options, and then, under Suppress, check Attributes or Operations.
Control which property values display on the N-ary Association Class shape
Right-click the shape, click Shape Display Options, and then select or clear options to show or hide values.
Create a diagram owned by the association class
Right-click the shape, click Diagrams, click New, choose the type of diagram you want, and then click OK.
Navigate to other views of the association class
Right-click the shape, click Views, select the view you want, and then click OK.