There are different options to implement the tasks of a Grab activity. Each option addresses specific types of interaction.
The default implementation type is method.
For more information about the different implementation types, see Flow Object Tasks.
You can run optional tasks while you are running the main task of a Grab activity. These tasks are usually related to the main task. They provide information that you might need to complete the Grab activity.
Optional tasks are repeatable and read-only. They are not allowed to modify the instance information because this information is used by the main task.