Robert Horn <rjh...@panix.com> writes: >> 1. Time (YYYY-MM-DD HH:MM) not continuous and may change arbitrarily at >> certain times a year or in future or in the past: >> - DST transitions are not stable and change from year to year >> according to strange rules that may involve Julian dates or >> counting weekdays >> - DST transition rules may change over time >> - The new year day itself is not necessarily fixed (England >> - Julian/Gregorian transitions happened at different times in >> different countries > > Note that as a result "time when it happened" has different rules than > "future time when it is scheduled". There are lots of other times that are > scheduled as "future local time, subject to changing DST rules". This > is particularly tricky for repeating times for regularly scheduled events.
Not really. Countries may change DST at any moment in future. Or decide to switch calendars (consider countries near the day transition line). And "past local time, according to the DST rules in effect at the time" is also an option that might be useful in certain scenarios. >> 5. Leap seconds! 23:59:59 -> 23:59:60 -> 00:00:00, according to >> astronomical Earth observations > > Fortunately, the most recent vote reached majority for eliminating leap > seconds, hopefully within 8 years. But we will have to keep supporting all the leap seconds that already happened! So it does not really help all that much wrt timestamp design. -- Ihor Radchenko // yantar92, Org mode contributor, Learn more about Org mode at <https://orgmode.org/>. Support Org development at <https://liberapay.com/org-mode>, or support my work at <https://liberapay.com/yantar92>
