There are two ways to tell if the timing belt has been replaced. One is obvious-you are looking at a service receipt showing the replacement.
Swimlane diagrams are used whenever you need to show activities, tasks, or process steps which are being performed by different actors/roles. You can use swimlanes to group activities in an activity diagram or process flow by any category what you need: by role, by system, by department, etc.
You can get more information about how to use OpenOffice to draw process maps in the Resources module of the training. Swimlane Template. One reason Visio is such an excellent tool for drawing process maps is that it has a built-in template for creating swimlane maps.