You can restrict backend users and groups to edit records only in specific languages. The permissions are enforced over all tables by checking the language defined in the :rec:`"languageField" of the table <core-support-tca-languagefield>`. The "Limit to languages" setting is found in the "Access Lists" tab:
Settings from groups and sub-groups are all added together.
If a user has no "Limit to languages" checkboxes set at all he can edit all languages .
Regardless of "Limit to languages" all users can edit records with "[All]" language.
Setting "Limit to languages" is not only good to protect translators from editing other languages or default content - it is also helpful to limit the confusion a user might have when faced with modules displaying translations for a host of other languages!