1--- 2layout: default 3title: Standards Update 4parent: Release & Milestone Tasks 5grand_parent: Contributors 6nav_order: 110 7--- 8 9<!-- 10© 2021 and later: Unicode, Inc. and others. 11License & terms of use: http://www.unicode.org/copyright.html 12--> 13 14# Standards Updates 15{: .no_toc } 16 17## Contents 18{: .no_toc .text-delta } 19 201. TOC 21{:toc} 22 23--- 24 25## Time Zones 26 27Make sure the timezone (Olson) data is up to date. 28 29Olson timezone data should be regularly updated in the trunk. If the data is out 30of date, follow the instruction described in the 31[readme](https://github.com/unicode-org/icu-data/blob/main/tzdata/readme.txt) 32file. 33 34Once the timezone resource file is generated by the process above, the file 35should be checked into 36[zoneinfo64.txt](https://github.com/unicode-org/icu/blob/main/icu4c/source/data/misc/zoneinfo64.txt) 37in the trunk. 38 39## Unicode 40 41### Update Unicode Data 42 43See the [Unicode Update page](../../unicode-update.md) for an overview, and the 44[change log for Unicode updates](https://github.com/unicode-org/icu/blob/main/icu4c/source/data/unidata/changes.txt) 45for details. 46 47### Update script code enums 48 49Starting with ICU 55, we do not add UScriptCode constants for new scripts any more 50until they are encoded in Unicode, 51or can be assumed to be encoded in the next Unicode version. 52 53Script enum constant names want to follow the Unicode script property value aliases, 54which are assigned only when the scripts are encoded. 55When we encode scripts early and guess wrong, then we have confusing enum constants 56and have sometimes added aliases. 57 58Normally, we add script codes during the ICU update for a Unicode beta, 59at the same time as we add new API constants for new Unicode blocks and 60for new values of other supported properties. 61 62Variant script codes like Latf and Aran that are not subject to separate encoding 63can be added at any time. 64(For example, Aran could be added as USCRIPT_ARABIC_NASTALIQ.) 65 66We add script codes used in CLDR or in the spoof checker. 67This includes combination/alias codes like Hanb and Jamo. 68See https://unicode.org/reports/tr35/#unicode_script_subtag_validity 69and look for "alias" on https://unicode.org/iso15924/iso15924-codes.html 70 71We add special Z* script codes like Zsye. 72 73For new script codes see https://www.unicode.org/iso15924/codechanges.html 74Check for recent changes with the code highlighted in the left column and 75"Add" in the right column. 76 77Update script code enums with new codes from ISO 15924, send a notice for them 78as public API (born `@stable`) to the icu-design list. 79 80See details in the 81[change log for Unicode updates](https://github.com/unicode-org/icu/blob/main/icu4c/source/data/unidata/changes.txt). 82 83## CLDR 84 85### Sync ICU with CLDR and tag CLDR. 86 87Update ICU data from CLDR, tag CLDR. Instructions 88[here](https://github.com/unicode-org/icu/blob/main/icu4c/source/data/cldr-icu-readme.txt). 89 90### Update MeasureUnit Code 91 92<https://github.com/unicode-org/icu/blob/main/docs/processes/release/tasks/updating-measure-unit.md> 93 94## ISO 4217 numeric codes 95 96Make sure the ISO 4217 numeric code mapping data is up to date. 97 98See the instruction in 99<https://github.com/unicode-org/icu/blob/main/tools/currency/readme.txt> 100