The Role Tool
is used to specify the
role that an object plays in a relationship. 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
.
Figure 2–14. Role Tool.
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.