Hi everyone, I am writing this mail with my distribution maintainer hat on since I am responsible for keeping the tzdata package up-to-date in Ubuntu. I like to propose to have a single source of truth for timezone data, which should be the tzdata source package. Updating this package in a distribution like Debian/Ubuntu should be enough to update all consumers in the distribution. Sadly this is currently not the case. Ubuntu since 20.04 (focal) adds the four icu source files metaZones.txt, timezoneTypes.txt, windowsZones.txt, and zoneinfo64.txt from https://github.com/unicode-org/icu-data to the tzdata source package. Then it uses genrb and icupkg to generate the .res files. Since the icu project lacks behind the tzdata release by hours up to days, Ubuntu has to update tzdata twice (first the tzdata release, then the icu update). metaZones.txt, timezoneTypes.txt, and windowsZones.txt are generated using tools/cldr/cldr-to-icu/build-icu-data.xml from https://github.com/unicode-org/icu. zoneinfo64.txt is generated by tz2icu. build-icu-data.xml uses https://github.com/unicode-org/cldr as input to convert the cldr data to icu. If I saw that correctly, only common/supplemental/metaZones.xml needs to be updated there on an update. Can tzdata include the necessary data and tools to generate metaZones.xml from its source? Then it would be possible to generate the icu data from the tzdata source without the need to wait for icu to catch up. Then Debian/Ubuntu can ship a tzdata-icu package for it [1]. [1] https://bugs.debian.org/954112 -- Benjamin Drung Debian & Ubuntu Developer