The workflow must not include looped sequence flows. Each sequence flow can run one time.

The Start event has a single outgoing sequence flow.

The sequence flow that leads from the Start event does not include a condition.

The End event has a single incoming sequence flow.

Each task has a single incoming sequence flow and a single outgoing sequence flow.

Each gateway has either multiple incoming sequence flows or multiple outgoing sequence flows, but not both. A gateway that splits the workflow has at least two outgoing sequence flows, with one of the sequence flows set as the default. A gateway that merges the workflow does not have a default outgoing sequence flow.

An expression in a conditional sequence flow must return a boolean or integer value. The expression cannot contain a carriage return character or a line feed character.