Unicode CLDR 49 is now available and has been integrated into version ICU 79 and ICU4X 2.4. Some of the most significant changes in this release are:
Replaced the backronym for CLDR
“Common Locale Data Repository (CLDR)”
→ “Common Locale Data & Rules (CLDR)”Aligned the title of the CLDR specification
“UTS #35: Unicode Locale Data Markup Language (LDML)”
→ “UTS #35: Unicode Common Locale Data & Rules (CLDR)”.Updated for Unicode 18, including annotations for the new emoji, changes to sorting order, etc.
Added new date & time formatting features including:
Localized patterns for gluing date & timezoneAppend Items — e.g., Sept 3, EST
Ordinal days in dates — e.g., Sept 3rd
Customizing numeric datetime separators in patterns: 3-10-2031 → 3/10/2031
Dual format for zones with two offsets (summer and winter) — eg, GMT-8/-7
Deprecated Japanese era data before Meiji
Structure for preventing digit-digit merges — e.g., ‘2026/1/29 GMT-817时’ → ‘2026/1/29 GMT-8 17时’
Additional skeleton-patterns added for flexible and interval date formats
Added new units (conversions and formatting)
Added nested bracket replacement — for constructing locale names with parts that have parentheses, eg, ”birmanês (Mianmar [Birmânia])”
Added many additional localized locale option names for use in menus, such as calendar and number-system names
Updated to the most recent versions of external standards and data sources, such as the language subtag registry, UN M49 macro regions, ISO 4217 currencies, etc.
Added many specification changes, both for features above, and clarifications of particular processes relevant to conformance.
Added client coverage data — per-path coverage data in a format that is easy for clients to use and relatively small
See the CLDR 49 release note for more details on the changes, information on accessing the data, reviewing charts of the changes, and — importantly — Migration issues and Advance Warnings.
CLDR is the foundational source of internationalization locale data, powering every major operating system and browser, software libraries like ICU4C, ICU4J, and ICU4X, and many programming languages (Java, JavaScript, Swift, etc. — see Who uses CLDR?). The data includes complex, language-specific rules, as well as translations. These rules include many patterns and other structures that are used by internationalization libraries to process components, and format UI variables and messages. The CLDR specification provides requirements and guidance for generating conformant values. It covers many features, including dates, times, numbers, and currency amounts; display names for languages and regions; measurement unit display names, locale preferences, and conversion; plural rules; and locale sorting (collation) rules.
There are 3 coverage levels for each locale, where the requirements for coverage are raised for each release. Coverage levels are also a factor in determining which languages are supported on mobile phones and computer operating systems. For more details (including languages that changed coverage) see Locale Coverage Status in the release page.