---
title: "FormatRule – API-Referenz · Quittio"
description: "A rule of a country pack that decides the output format of an invoice."
canonical_url: "https://quittio.dev/docs/api/Quittio/Core/Formats/FormatRule"
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---

> Index of every page on this site: [llms.txt](https://quittio.dev/llms.txt)

[API reference](https://quittio.dev/docs/api) / [Quittio](https://quittio.dev/docs/api/Quittio) \\ [Core](https://quittio.dev/docs/api/Quittio/Core) \\ [Formats](https://quittio.dev/docs/api/Quittio/Core/Formats)

# FormatRule

interface in quittio/core

`Quittio\Core\Formats\FormatRule` · [Source](https://github.com/Quittio/quittio/blob/v0.7.1/packages/core/src/Formats/FormatRule.php#L12)

A rule of a country pack that decides the output format of an invoice.

## Methods \#

| Method | Description |
| --- | --- |
| `->resolve()` | Returns a format for the invoice, or null if the rule does not apply. |

### `resolve()`#

```
public function resolve(InvoiceData $invoice): ?FormatChoice
```

Returns a format for the invoice, or null if the rule does not apply.

| Parameter | Type | Description |
| --- | --- | --- |
| `$invoice` | `[InvoiceData](https://quittio.dev/docs/api/Quittio/Core/Data/InvoiceData)` | |

<dl><dt>Returns</dt>
<dd><code>?<a href="https://quittio.dev/docs/api/Quittio/Core/Formats/FormatChoice">FormatChoice</a></code></dd>
</dl>

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