# BPMN notation reference

BPMN has a large vocabulary and a small core. This is the reference for the whole thing: what each symbol means, and the rules about which may connect to which.

If you are learning it, read events, gateways and flows first. Those three cover most real models.

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## When it matters

* Reading a BPMN model somebody else drew.
* Reviewing a model that will be executed, where notation is behaviour.
* Settling an argument about whether a line should be dashed.

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## The symbols

| **Symbol** | **Means**                                                      |
| ---------- | -------------------------------------------------------------- |
| Events     | Circles. Something happens: start, timer, message, error, end. |
| Activities | Rounded rectangles. Work, done by a person or a system.        |
| Gateways   | Diamonds. The path splits or joins.                            |
| Flows      | Solid within a pool, dashed between pools.                     |
| Swimlanes  | Pools for participants, lanes for roles.                       |
| Artifacts  | Data objects, stores, groups and annotations.                  |

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## A few things that catch people out

* The rule that catches everyone: sequence flow never crosses a pool boundary.
* Marker icons are semantics, not decoration. A service task and a user task behave differently.
* A model you cannot explain without annotations is usually over-modelled.

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## Related

[DMN notation referenceDecision tables, FEEL, and the requirement diagram.](https://help.gocapable.com/diagrams/dmn-notation-reference.html)

[ExamplesWorking diagrams you can copy.](https://help.gocapable.com/diagrams/examples.html)

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_The notation is the meaning._