[lolc]

> I still don't understand the arguments about a future date requiring a timezone.

A future event at local time requires a location, because the timezone may yet change at that location. Suppose we meet Nov 1st 2017 in Istanbul and decide to repeat this the year after. We agree to meet again Nov 1st 2018 in Istanbul 10:00 local time. This meeting would have been projected to happen at UTC 8:00, because Turkey was scheduled to switch to UTC+2 on October 30 2018.

However, the government decided to not change the timezone and stay on UTC+3. So our meeting, being scheduled for 10:00 local time, would move from UTC 8:00 to UTC 7:00 at the stroke of a pen. If your software had recorded UTC time, it would be ignorant of this change and consequently it would show the meeting at 11:00 local time. You'd be one hour late.

This change in the tz DB is a little window into the questionable cultural achievement that is local time: https://github.com/eggert/tz/commit/e15ef79a603a2fba89ad8f38...