Normally, we record an action below a line under the transition's trigger.
There have two kinds of actions: noninterruptible actions and interuptible actions. noninterruptible actions are the actions that when they start running, it can not be interrupted unless the system error happens. Interrptible actions can be interrupted and resumed later.
Compare with actions, we use state or sometimes even entire state net to represent activities or process. See also: state transition
Here is a short quiz so you can test your understanding of Actions.
Go to the OSA Tutorial ORM
Go to Triggers, Conditions, and Events Initial Transition
Created Thurs Oct. 6 16:28:10 1994 ... Updated Thurs Nov. 23 13:25:12 1994 by Wei Wei (firstname.lastname@example.org)