Less trivial is taking into account time zones. if you're traveling and have some jet lag, "10:30" may not actually mean 10:30 to your biological clock. but "in one hour" is universal (even if your body is confused).
But if I am travelling it is even more error prone for my computer to compute the correct difference.
Less trivial is taking into account time zones. if you're traveling and have some jet lag, "10:30" may not actually mean 10:30 to your biological clock. but "in one hour" is universal (even if your body is confused).