A Start Event indicates where a particular process starts. In terms of sequence flows, a Start Event starts the flow of a process, and thus cannot have any incoming sequence flows.

When a Start Event is owned by an Event SubProcess, it can be:

• Interrupting. The Start Event interrupts the process contained in the Event SubProcess. The Interrupting Message Start Event is drawn with a solid border.
• Non-Interrupting. The Start Event does not interrupt the process contained in the Event SubProcess and starts parallel flow. The Interrupting Message Start Event is drawn with a dashed border.

Types of Start Events are as follows: