Coverage Levels

There are four main coverage levels as defined in the UTS #35: Unicode Locale Data Markup Language (LDML) Part 6: Supplemental: 8 Coverage Levels. They are described more fully below.


You can use the file common/properties/coverageLevels.txt (added in v41) for a given release to filter the locales that they support. For example, see coverageLevels.txt. (This and other links to data files are to the development versions; see the specific version for the release you are working with.) For a detailed chart of the coverage levels, see the locale_coverage.html file for the respective release.

The file format is semicolon delimited, with 3 fields per line.

Locale ID ; Coverage Level ; Name

Each locale ID also covers all the locales that inherit from it. So to get locales at a desired coverage level or above, the following process is used.


To filter "at that level or above", you use the fact that basic ⊂ moderate ⊂ modern, so 


As of v43, the files in /seed/ have been moved to /common/. Older versions of CLDR separated some locale files into a 'seed' directory. Some implementations used for filtering, but the criteria for moving from seed to common were not rigorous. To maintain compatibility with the set of locales used from previous versions, an implementation may use the above process for Basic and above, but then also add locales that were previously included. For more information, see CLDR 43 Release Note

Core Data

The data needed for a new locale to be added. See Core Data for New Locales for details on Core Data and how to submit for new locales.

It is expected that during the next Survey Tool cycle after a new locale is added, the data for the Basic Coverage Level will be supplied. 

Basic Data

Suitable for locale selection and minimal support, eg. choice of language on mobile phone

This includes very minimal data for support of the language: basic dates, times, autonyms:

Moderate Data

Suitable for “document content” internationalization, eg. content in a spreadsheet

Before submitting data above the Basic Level, the following must be in place:

The data for the Moderate Level includes subsets of the Modern data, both in depth and breadth.

Modern Data

Suitable for full UI internationalization

Before submitting data at the Moderate Level, the following must be in place:

The data for the Modern Level includes:

### TBD


For the coverage in the latest released version of CLDR, see Locale Coverage Chart.

To see the development version of the rules used to determine coverage, see coverageLevels.xml. For a list of the locales at a given level, see coverageLevels.txt