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What is CLDR?

What is CLDR?
What is CLDR?

If you are playing with localization (or is it internationalization?), you probably stumbled upon CLDR. What is it? Where does the idea come from? And how is it created? You’ll find answers on these and other questions in this article. Enjoy!

So, What Is It?

CLDR stands for Common Locale Data Repository. It’s repository of data relevant to localization, containing all language translations, date formats, country names, weekday order or currency names.

All data is stored in Locale Data Markup Language which is XML format purposed to store locale-dependant data. LDML is designed specifically to interchange specifications, so to reuse data you need to restructure it with some tools (for example with ICU library). Nowadays almost every library that’s handling locale-data will probably use CLDR as it’s most complete repository.


As applications started to be more wide-accessible, developers were in big need to apply many settings that depended on language and cultural conventions. Programmers spread all over the world were making their own efforts to handle all locale-specific user environment settings. As you can imagine, it wasn’t that easy.

So, it all started in 1999 with Linux Internationalization Initiative (abbreviated to LI18NUX), that aimed to connect all colaborative efforts on Linux I18n into one big project. They provided forum for technical discussions on localization problem, but most important is that they tried to provide specification that’ll be respected globally. Happily, website of project is still accessible via Internet Wayback Machine.

What happened next is that LI18NUX changed it’s name to OpenI18n to “better reflect the groups open source activities that go well beyond Linux“. OpenI18n group continued their efforts to provide specification for localization data, so it would consist locale form all over the world. At that time in 2002 they even started OpenI18N Certification as authority that verifies if specific linux distribution is adhering to internationalization standard.

First CLDR 1.0 revision was approved on 2004-01-16
First CLDR 1.0 revision was approved on 2004-01-16

Finally, CLDR 1.0 was approved on 2004-01-16 by the OpenI18N steering committee. The founding members of the workgroup were IBM, Sun and OpenOffice, as you can read on CLDR acknowledgments page. From that time, CLDR project was taken under Unicode Consortium wing and they’re responsible for it till now.

How Is It Created?

As CLDR is worldwide database and need to provide locale data from all over the world, it would be impossible to set up any corporate infrastructure to keep such data updated. Instead, creating CLDR databse is a collaborative project. Anyone can submit change proposals to current data, request feature or submit a bug.

Firstly, when data for new country/locale is received it is marked as draft, and at that moment it should consist only minimal set of data (exemplar characters, months, days, date/time formats, translations for a few countries, languages, currencies, etc.). Then proposal goes to resolution phase and process for gathering data begins. It’s important to gather example data from many local sources, and national standards organizations are encouraged to be involved in that process.

What’s important, even smallest communities can have their own locale. Check Kenian Samburu tribe locale in CLDR database. You’ll learn that United States dollar in samburu will be “Dola eel Marekani” and their date format will look like 2015-06-01.

Even Samburu tribe have their own locale in CLDR database?
Even Samburu tribe has their own locale in CLDR database

There may be situations, where data in CLDR database is different (for example, there’s diferent date format) than widely used in given locale. In that case, conflict is resolved depending on voting process. Users have different voting strength (members of Unicode Consosrtium get increased voting strength), and they’re voting in specific review cycles.

All process details are well described on CLDR Process page. You’ll find there all information about submission and vetting process, how you can give some feedback or how you can contribute to CLDR project.

And that’ll be the end of this article. If you found something new or useful for yourself, let me know in comments. And if you want to receive information on new articles – subscribe (no spam – only information on updates)!.

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