Note non-existing times mostly happen when you go from winter time to summer time. You set the clock ahead an hour at let's say 2:00 in the morning. So you go directly from 2:00 to 3:00. 2:30 does not exist.
So let's say that you plan a meeting at 2:30 in the morning in a country that does not use DST. Then they decide to use DST and set the clocks forward one hour at 2:00. Your meeting was supposed to take place at 2:30 local time, but that time no longer exists! As I see it, the right thing to do is to alert the user of the problem.
Note non-existing times mostly happen when you go from winter time to summer time. You set the clock ahead an hour at let's say 2:00 in the morning. So you go directly from 2:00 to 3:00. 2:30 does not exist.
So let's say that you plan a meeting at 2:30 in the morning in a country that does not use DST. Then they decide to use DST and set the clocks forward one hour at 2:00. Your meeting was supposed to take place at 2:30 local time, but that time no longer exists! As I see it, the right thing to do is to alert the user of the problem.