Another problem here is that DST is political, and under local political control. Politicians don't get why changes in timscales have to be announced well in advance; there have been cases where they were announced as little as a month before they came effect.
Some commenters seem to wonder why people care about the relationships between timescales, and how to convert between them. Well, contracts seems to be a good example. It could be vitally important to know, to the second, when a 200-year-old contract came into force.
Some commenters seem to wonder why people care about the relationships between timescales, and how to convert between them. Well, contracts seems to be a good example. It could be vitally important to know, to the second, when a 200-year-old contract came into force.