Thank you, I have made a docker image which can be pulled from: "docker.io/damon0708/zic:v0.1". The DockerFile is simple: FROM alpine WORKDIR /app/ RUN apk add tzdata The image has been installed a tzdata with zic and zoneinfo in /usr/share/zoneinfo, which version is 2021a.You can pull it to local and run a container from it by "docker run -ti damon0708/zic:v0.1 /bin/sh". After running a container, # zic --version zic (tzcode) 2021a # mkdir tzdata2021a && cd tzdata2021a # wget https://data.iana.org/time-zones/releases/tzdata2021a.tar.gz # tar zxf tzdata2021a.tar.gz<https://data.iana.org/time-zones/releases/tzdata2021a.tar.gz> # mkdir ../zoneinfo # zic -d ../zoneinfo/ -L leapseconds africa antarctica asia australasia europe northamerica southamerica etcetera backward factory # cp -f iso3166.tab zone1970.tab zone.tab ../zoneinfo/ # diff ../zoneinfo/America/Adak /usr/share/zoneinfo/America/Adak Files America/Adak and /usr/share/zoneinfo/America/Adak differ I ran the same check, still got the result: zone local time by 2021a utc time by 2020d utc time America/Adak 2022-11-01 00:00:00 2022-11-01 09:00:00 2022-11-01 10:00:00 America/Anchorage 2022-11-01 00:00:00 2022-11-01 08:00:00 2022-11-01 09:00:00 America/Asuncion 2022-10-01 00:00:00 2022-10-01 04:00:00 2022-10-01 03:00:00 America/Atka 2022-11-01 00:00:00 2022-11-01 09:00:00 2022-11-01 10:00:00 By the way, I also used the zic(version: @(#)zic.c 8.22) in mac os to generate zoneinfo data, but the check showed no diff in America/Adak America/Anchorage America/Asuncion America/Atka. ________________________________ 发件人: Paul Eggert <eggert@cs.ucla.edu> 发送时间: 2021年3月4日 1:41 收件人: 汪蒙蒙（木之） <wangmm@tuya.com> 抄送: Time zone mailing list <tz@iana.org> 主题: Re: [tz] zoneinfo generating issues On 3/3/21 3:20 AM, 汪蒙蒙（木之） via tz wrote:
Those zones are not changed from version 2020d to 2021a. I am very confused and not sure if I generated the zoneinfo in the right way.
As Brian wrote, we'd need more info before being able to help much. That being said, you can check things by comparing your 2020d America/Adak file to your 2021a America/Adak file. They ought to be identical. If they're not, it's a problem with how you generated the files. If they are, it's a problem with the program you wrote.