# Sequence diagram (SeqDiag)

SeqDiag trades features for brevity. An arrow is a message, a double arrow is a call with its return, and that is most of the language.

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## What this example shows

* The => form, which draws a call and its return in one line.
* Explicit return labels.
* Participants ordered by first mention.

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## A worked example

Open it, edit it, or copy the source below.

![Sequence diagram (SeqDiag)](https://help.gocapable.com/images/att1423540280.svg)

The source, which you can paste into a new diagram and edit:

```
seqdiag {
  browser  -> web    [label = "GET /orders"];
  web      => api    [label = "getOrders(userId)", return = "orders"];
  api      => db     [label = "SELECT * FROM orders", return = "rows"];
  api      -> cache  [label = "warm cache", note = "fire and forget"];
  browser <-- web    [label = "200 OK"];
}
```

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## Making it your own

* Mention participants in the order you want them drawn.
* The => form halves the length of a long sequence.
* For activations, alt blocks and loops, use Mermaid or PlantUML.

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## Related

[Network diagram (NWDiag)Networks as bands, with real addresses.](https://help.gocapable.com/diagrams/network-diagram-nwdiag.html)

[Packet diagram (PacketDiag)Bit offsets, computed rather than drawn.](https://help.gocapable.com/diagrams/packet-diagram-packetdiag.html)

[More languagesBack to the rest of these examples.](https://help.gocapable.com/diagrams/more-languages.html)

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_Specialists. Borrow one when you need it._