---
title: "Localization in Extbase"
manual: "TYPO3 Explained"
version: "main"
permalink: "https://docs.typo3.org/permalink/t3coreapi:extbase-localisation@main"
source: "ExtensionArchitecture/Extbase/Localization/Index.rst"
rendered: "2026-09-17T18:20:57+00:00"
---

# Localization in Extbase {#localization-in-extbase}

> [!WARNING]
> The information on this page might be outdated!

## Localization of Extbase models {#localization-of-extbase-models}

### Identifiers in localized models {#identifiers-in-localized-models}

Domain models have a main identifier `uid` and an additional property
`_localizedUid`.

Depending on whether the [overlay type](https://docs.typo3.org/permalink/t3coreapi:context-api-aspects-language-overlay-types@main)
language aspect is enabled (`LanguageAspect::OVERLAYS_ON` or
`LanguageAspect::OVERLAYS_MIXED`) or disabled (`LanguageAspect::OVERLAYS_OFF`),
the identifier contains different values.

When the overlay language aspect is enabled, then the `uid`
property contains the `uid` value of the default language record and
the `uid` of the translated record is kept in the `_localizedUid`.

| Context | Record in language 0 | Translated record |
| --- | --- | --- |
| Database | uid:2 | uid:11, l10n_parent:2 |
| Domain object values with Overlay language aspect enabled | uid:2, \_localizedUid:2 | uid:2, \_localizedUid:11 |
| Domain object values with Overlay language aspect disabled | uid:2, \_localizedUid:2 | uid:11, \_localizedUid:11 |

> [!TIP]
> **Hint**
>
> If your project uses [`typo3/cms-workspaces`](https://packagist.org/packages/typo3/cms-workspaces) there is yet another
> additional property, `_versionedUid`. Refer to the
> [Workspaces documentation](https://docs.typo3.org/c/typo3/cms-workspaces/main/en-us/Index.html) for details on
> workspace overlays.

## Translating labels {#translating-labels}

This chapter covers how Extbase handles *records* across languages. Translating
the *labels* of an extension — button captions, flash messages, validation
errors — is a separate topic:

> [!NOTE]
> **See also**
>
> -   [Translating labels in Extbase](https://docs.typo3.org/permalink/t3coreapi:extension-localization-extbase@main) —
>     in controllers and other PHP code
> -   [LocalizationUtility API reference](https://docs.typo3.org/permalink/t3coreapi:extbase-localization-utility-api@main)
>     — all parameters of `translate()`
> -   [Translating labels in Fluid](https://docs.typo3.org/permalink/t3coreapi:extension-localization-fluid@main) —
>     the `<f:translate>` ViewHelper