* Paul Eggert:
Please see:
https://data.iana.org/time-zones/tz-link.html#changes
which says this:
If your government plans to change its time zone boundaries or daylight saving rules, inform tz@iana.org well in advance, as this will coordinate updates to many cell phones, computers, and other devices around the world. With less than a year's notice there is a good chance that some computer-based clocks will operate incorrectly after the change, due to delays in propagating updates to software and data. The shorter the notice, the more likely clock problems will arise; see "On the Timing of Time Zone Changes"<https://codeofmatt.com/on-the-timing-of-time-zone-changes/> for examples.
Note that the notice period of one year is from the time the rule change becomes official to when the difference becomes observable in practice (in other words, when the rule change becomes effective). This is not the same as the time from the start of the entire process to the time it becomes effective, but this is the way most officials appear to interpret it. Most rule change proposals are in legal limbo for a long period of time, and close to all of them fail to become effective. This means that distributors of the time zone database can do little to prepare when the process starts. Instead, they have to wait until changes become official. Only at that point, it is possible to distribute updates that change time zone rules for future dates. One thing that might also come as a surprise (particulaly for DST changes or any change at a DST boundary) is that the database format is sufficiently flexible to express a rule change at an arbitrary future date. It is not restricted to making the change at the next DST transition. This means that distributors of the time zone database can act on any official change immediately, making full use of the notification period. Thanks, Florian -- Red Hat GmbH, https://de.redhat.com/ , Registered seat: Grasbrunn, Commercial register: Amtsgericht Muenchen, HRB 153243, Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs, Michael O'Neill