In a highly readable process model, there should always be one or more inputs and its equally important to describe what the result of the process is by an output. The input could be both what should be processed and what’s triggering something being carried out.
The expected result from an activity is often input to the following activity. By visualizing the result from an activity we achieve a distinctness in the fact that its the same output as input between two activities.
In addition to the flow of activities, roles and positions are also used in the process model to describe who is responsible for a certain activity.