# Currency

The currency a product charges is a fact of the product, declared once in `aircloud.toml` as an ISO 4217 code:

```toml
[i18n]
default_locale = "pt-BR"
available_locales = ["pt-BR", "en"]
currency = "BRL"
```

Formatting an amount with `numberToCurrency` renders it in the product's currency under every locale: the currency
gives the code and the default number of fraction digits (its ISO 4217 minor unit — two for BRL, none for JPY), and
the viewer's locale gives the symbol and the pattern. A product charging BRL shows reais to every visitor, as
`R$ 1.234,50` in `pt-BR` and `R$1,234.50` in `en`. A call's `precision` overrides the fraction digits, and a call's
`unit` formats an amount that is in another currency.

The currency is never assumed. Without `[i18n] currency`, a release whose code formats a currency the build can see
is refused, and a formatting call that only runs at run time renders the generic currency sign `¤`.

A value that carries its own currency — an amount Air-Billing billed — is formatted in that currency, never in the
product's default.

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Rendered from aircloud 0.1.12 at commit d84a0ce6dae53629277f656d96d81549df36807e.