> ## Documentation Index
> Fetch the complete documentation index at: https://api-doc.fidly.be/llms.txt
> Use this file to discover all available pages before exploring further.

# Reference lists

> Units, currencies and countries: fill a document or an address without hardcoding.

Three read-only lists provide every code a document or an address can carry. They
require a valid token but **no resource permission**, and are identical in sandbox
and live.

`language` is a **required** query parameter (`fr`, `en`, `nl`, `de`): it selects
the language of the returned labels. An unknown language returns
`400 invalid_filter`; a missing one, `422 validation_error`.

| Endpoint                            | Returns                 | Translated       |
| ----------------------------------- | ----------------------- | ---------------- |
| `GET /units-of-measure?language=fr` | `{code, symbol, label}` | symbol and label |
| `GET /currencies?language=fr`       | `{code, symbol, label}` | label only       |
| `GET /countries?language=fr`        | `{code, label}`         | label            |

## Guarantees

A list never proposes a code the API would then refuse, and never hides a code the
API accepts. Validation of `unit_code`, `currency` and `country_code` on writes
uses the same data as these lists.

### Units

Only **active** units are listed, but a withdrawn unit remains accepted on
document creation.

### Countries

The set is the Peppol code list, based on the ISO 3166-1 alpha-2 standard. A
handful of accepted codes have no translation yet and return `label: null`.