Standards Updates


  1. Time Zones
  2. Unicode
    1. Update Unicode Data
    2. Update script code enums
  3. CLDR
    1. Sync ICU with CLDR and tag CLDR.
    2. Update MeasureUnit Code
  4. ISO 4217 numeric codes

Time Zones

Make sure the timezone (Olson) data is up to date.

Olson timezone data should be regularly updated in the trunk. If the data is out of date, follow the instruction described in the readme file.

Once the timezone resource file is generated by the process above, the file should be checked into zoneinfo64.txt in the trunk.


Update Unicode Data

See the Unicode Update page for an overview, and the change log for Unicode updates for details.

Update script code enums

Starting with ICU 55, we do not add UScriptCode constants for new scripts any more until they are encoded in Unicode, or can be assumed to be encoded in the next Unicode version.

Script enum constant names want to follow the Unicode script property value aliases, which are assigned only when the scripts are encoded. When we encode scripts early and guess wrong, then we have confusing enum constants and have sometimes added aliases.

Normally, we add script codes during the ICU update for a Unicode beta, at the same time as we add new API constants for new Unicode blocks and for new values of other supported properties.

Variant script codes like Latf and Aran that are not subject to separate encoding can be added at any time. (For example, Aran could be added as USCRIPT_ARABIC_NASTALIQ.)

We add script codes used in CLDR or in the spoof checker. This includes combination/alias codes like Hanb and Jamo. See and look for “alias” on

We add special Z* script codes like Zsye.

For new script codes see Check for recent changes with the code highlighted in the left column and “Add” in the right column.

Update script code enums with new codes from ISO 15924, send a notice for them as public API (born @stable) to the icu-design list.

See details in the change log for Unicode updates.


Sync ICU with CLDR and tag CLDR.

Update ICU data from CLDR, tag CLDR. Instructions here.

Update MeasureUnit Code

ISO 4217 numeric codes

Make sure the ISO 4217 numeric code mapping data is up to date.

See the instruction in