> ## Documentation Index
> Fetch the complete documentation index at: https://docs.glialhealth.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Languages

> Control OCR and extraction language with the language parameter.

Folio supports English (`en`) and French (`fr`) documents, with automatic language detection (`auto`) enabled by default. Use the `language` form field to influence OCR accuracy and extraction quality.

## The `language` parameter

| Value  | Behaviour                                                               |
| ------ | ----------------------------------------------------------------------- |
| `auto` | Folio detects the document language automatically. This is the default. |
| `en`   | Force English OCR and extraction.                                       |
| `fr`   | Force French OCR and extraction.                                        |

```bash theme={null}
curl -X POST https://api.glialhealth.com/v1/documents \
  -H "Authorization: Bearer sk_test_..." \
  -F file=@ordonnance.pdf \
  -F language=fr
```

The detected (or forced) language is echoed back in the document object's `language` field:

```json theme={null}
{
  "id": "doc_01j9xkqz...",
  "language": "fr",
  "status": "completed"
}
```

## When to use `auto` vs. explicit

**Use `auto` (default)** when:

* Your document corpus contains a mix of English and French documents and you don't know the language at submission time.
* You want Folio to handle language detection without adding any logic on your side.

**Use an explicit language (`en` or `fr`) when:**

* You know the document language in advance and want to avoid a small detection overhead.
* OCR accuracy for a specific language is critical and you want to eliminate any ambiguity from the classifier.
* Documents contain a mix of characters but should be treated as one primary language (e.g. an English form with a few French words).

## Bilingual documents

Some documents (e.g. Canadian government forms, Quebec-regulated health records) contain content in both English and French. In these cases:

* **Use `auto`**: Folio will detect the dominant language and apply the best OCR model for that language. Fields in the secondary language are still extracted with reasonable accuracy.
* Extraction field values are returned in whichever language they appear in the source document — Folio does not translate values.

<Note>
  If bilingual accuracy is critical for your use case, test both `auto` and each explicit language against a representative sample of your documents and compare the per-field confidence scores in the result.
</Note>

## Language and extraction schemas

Language does not affect how extraction schemas are defined or applied. Schema `key` names, `type` constraints, and `pattern` checks are language-agnostic. When using `hint` values in a schema, writing the hint in the same language as the target documents may improve extraction accuracy.