# Class hierarchy (Nomnoml)

Nomnoml's whole syntax is brackets and arrows. It is the quickest way to sketch a class model, and it has a distinctive look that suits a design note.

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## What this example shows

* Directives controlling direction and spacing.
* Compartments, separated by pipes.
* Inheritance, composition and association arrows.

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## A worked example

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

![Class hierarchy (Nomnoml)](https://help.gocapable.com/images/att1424228466.svg)

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

```
#direction: down
#spacing: 40
#fill: #f8fafc
#lineWidth: 1

[<abstract>Payment|
  amount: Money;
  currency: string|
  authorise();
  capture()
]

[Payment] <:- [CardPayment|
  last4: string;
  scheme: string
]
[Payment] <:- [BankTransfer|
  iban: string
]

[CardPayment] +-> [Card|
  last4: string;
  expiry: date
]

[Order|
  id: uuid;
  status: OrderStatus|
  total()
] o-> [Payment]

[Order] +-> [OrderItem|
  quantity: int;
  unitPrice: Money
]
```

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## Making it your own

* Directives at the top control the whole diagram; there is no per-node styling to learn.
* Pipes separate compartments, semicolons separate the lines inside one.
* For sequence and activity diagrams, use PlantUML.

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## Related

[Architecture diagram (Pikchr)Each object placed relative to the last.](https://help.gocapable.com/diagrams/architecture-diagram-pikchr.html)

[Signal timing (WaveDrom)Clock, chip select and data, character by character.](https://help.gocapable.com/diagrams/signal-timing-wavedrom.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._