Would there be any support in this community for adding new Etc/GMT[-+] zone identifiers but with partial hours? e.g. something like "Etc/GMT-5:30" These might introduce some technical challenges, but I can see a use which I will explain below. I haven't yet investigated the impact on Android (where I deal with much of the time zone work), but I thought I'd ask for thoughts before expending any effort prototyping. Thanks, Neil. ------------------ Motivating case: Taking Android as an example, the platform uses TZDB zone identifiers as the basis for most time zone support. Directly, via a tzif-based file (used for libc mktime/localtime / Android's custom implementation of java.util.TimeZone), and indirectly via ICU4C and ICU4J. In situations like we had this week with Palestine, i.e. less than one week's notice before a DST transition change, the usual advice for users affected is "Please manually select an alternative time zone that has the offset you need until you receive a software update". e.g. Microsoft Windows appears to do the same [1] Side note: There are related cases for devices that have fallen out of their OEM's support window and will never receive a TZDB update again. The utility of these devices can degrade over time as their version of TZDB slowly drifts from the user's reality. Users continuing to use these devices may no longer be able to use the identifier for their actual location and get the behavior they need. Instead, they have to select an alternative zone ID that has the offset they need. If they're not lucky, they may be forced to pick an alternative zone ID which has its own DST schedule which might not match their requirements for the full year. The Stock Android settings UI, starting with Android Pie (9.0), allows users to select from the fixed "Etc/GMT-5" style identifiers from TZDB in addition to the more regular "Europe/London"-style zone identifiers associated with geographical regions. The original use case for this was to allow pilots to select Etc/UTC, and we added support for selecting all the other fixed Etc/GMT[+-] zones at the same time. The current Etc/GMT[+-] zone identifiers in TZDB only cover whole hour offsets. There are various places that use 30 minute offsets, and a few that use 45/15 minute offsets [2]. For the cases where devices cannot receive rules updates (in time, or at all), it would be useful to have the full range of 30-minute fixed-offset possibilities for users to select from instead. I'm choosing to ignore the 15/45 minute ones right now as they appear much less common / useful. Because most of our infrastructure treats TZDB as "ground truth" it would be beneficial to get this support in TZDB rather than carrying local patches to each library. [1] https://techcommunity.microsoft.com/t5/daylight-saving-time-time-zone/interi... - this example is for Fiji / 2020b [2] https://www.timeanddate.com/time/time-zones-interesting.html - zones with offsets other than integer hours -- Google UK Limited Registered Office: 6 Pancras Square, London, N1C 4AG Registered in England Number: 3977902