For many purposes the correct specification of a future time is in terms of local time at a particular location on that date. This is true for financial contracts (including trillions of dollars in options markets -- 10am in New York means NY time) but also of work schedules (scheduled to arrive at 9am? That is on the workplace clock, not UTC), local transit schedules, and many other things.
That means when daylight savings time rules change or timezone lines are moved the UTC time of these events change.
Unfortunately I don't believe anyone has standardized a format for storing times which are specified local time at a specified location on a specified date. So it is all roll-your-own or use UTC or zoned datetime and be burned when things change.
That means when daylight savings time rules change or timezone lines are moved the UTC time of these events change.
Unfortunately I don't believe anyone has standardized a format for storing times which are specified local time at a specified location on a specified date. So it is all roll-your-own or use UTC or zoned datetime and be burned when things change.