Sequence Flow

A sequence flow is a solid arrow with a filled arrowhead. It connects two flow nodes (activities, events, or gateways) inside the same pool. When the source node completes, its token travels along the sequence flow to the target node, which then starts. Sequence flows are the primary mechanism by which a process actually moves forward.

A sequence flow is unconditional by default: the token always takes it when the source completes. Adding a condition turns it into a conditional flow, marked with a small diamond at its source end. A default flow (marked with a short back-slash at its source) is the "else" path, taken only when no sibling conditional flow matches.

• Sequence flows stay inside a single pool. To cross a pool boundary, use a message flow.
• They can cross lane boundaries freely. A sequence flow from "Sales" lane to "Finance" lane just means a handover inside the same organisation.
• An activity must have at least one incoming sequence flow (unless it is a start event source) and at least one outgoing (unless it is an end event).
• Uniquely in BPMN 2.0: a sequence flow can be attached to a gateway, which decides how many of its outgoing sequence flows to activate.

Every sequence flow LucidFlow emits is stylable via the edge palette in the canvas and preserved in the BPMN 2.0 XML export. When the heatmap is enabled, sequence flows leading into hot nodes (activities with outsized cost or duration) inherit a subtle red tint so the path of the bottleneck is visible even at a zoomed-out view. Clicking a sequence flow shows its contribution to the overall process duration and, if it is a conditional flow, the branch probability used by the cost dashboard.