For example , a `` subscriber '' role type describes the property common to instances of the class `` Person '' when they participate in a `` subscribes-to '' relationship with the class `` Magazine '' .

In this example , there are three classes : NUMBER@1 -RRB- a class called `` car '' , NUMBER@2 -RRB- a class called `` pick-up truck '' , and NUMBER@3 -RRB- a class called `` vehicle '' . Although there is only one class called `` car '' , there could be many objects that are created from the class called `` car '' .
