Storing and comparing UTC is the minimum for sure but you often need to store local time and zone as entered and sometimes you do need to change what that is in

Storing and comparing UTC is the minimum for sure but you often need to store local time and zone as entered and sometimes you do need to change what that is in UTC after the fact. I worked on a internationally-focused scheduling application with clients in multiple timezones doing recurring events in future. Israeli customer's computers for instance could not be trusted to tell us the correct timezone so we needed to ask explicitly their intent then due the 'Israel Summer Time's offset being a political issue[1] we would have to fix up our calculations after the fact: [1] https://en.wikipedia.org/wiki/Israel_Summer_Time#2005.E2.80.932012 https://en.wikipedia.org/wiki/Israel_Summer_Time#2005.E2.80....