The Role Tool is used to specify the components that lie at the end of a relationship connected to an object. For example, for the Transition relationship in WatchApplication diagrams we can identify two role types: From and To, or for an Inheritance relationship type in UML Class Diagrams there could be Superclass and Subclass role types.

Roles can have properties of their own. For example, a role in the Association relationship in UML Class Diagrams has a property Cardinality.

Roles also have symbols that specify the width and color of the line from the object to the relationship, and also any symbol elements at the object end of the line. For instance, in a WatchApplication diagram the To role is a dark red 2 pixel solid line with an arrow head. If no symbol is defined, a simple black line with width 1 is used. Role types do not have custom icons.