Process Diagram Rules

The rules outlined below are based on best practice conventions. Process diagrams should be easy to read and be understood by coworkers as well as pass validation.

Sequence Flow Rules

• Every shape must be connected to another shape with a sequence flow connector. Neither end of a connector may be unconnected.
• Every diagram must start with a start shape and end with an end or terminate shape.
• All shapes other than end events must have an outgoing sequence flow.
• A gateway may not have a single conditional sequence flow out. It may have a single normal sequence flow out (no conditions).

• A gateway may have at most one default flow.

Start Event Rules

• A start event may not have an incoming sequence flow.
• Use a None Start shape in a reusable process diagram .

End Event Rules

• An end event can't have outgoing sequence flow.

Labeling Rules

• A task should be labeled in the manner: VERB-NOUN.
• Two activities in the same process should not have the same name, unless they are both call activities.
• A triggered start event should be labeled to indicate the trigger condition.
• A message start event should be labeled "Receive [message name]".
• A timer start event should be labeled to indicated the process schedule.
• A signal start event should be labeled to indicate the Signal name.
• An error start event should be labeled to indicate the trigger condition.
• A throwing intermediate event should be labeled.
• A catching intermediate event should be labeled.
• Throwing and catching events corresponding to the same signal event definition should have matching labels, if they occur in the same model.
• An end event should be labeled with the same name of the end state.
• An exclusive gateway should have at most one unlabeled gate.
• The label of a child-level diagram (page) should match the name of the call activity.