E.g. a rather trivial example of displaying a hourly graph/table of some measurement, including comparison with yesterday (because there are daily patterns of fluctuation).
DST means that some of days have 23 hours and some days have 25 hours. The libraries will help you make the relevant calculations, but now you have to make a decision wether the comparison that you make with "yesterday equivalent" of today's 11:00 is yesterday's 11:00 (23 hours ago) or yesterday's 10:00 (24 hours ago).
For another example, accounting of hours worked - you may have a person that has worked 25 hours in a single day, such events break some systems.
E.g. a rather trivial example of displaying a hourly graph/table of some measurement, including comparison with yesterday (because there are daily patterns of fluctuation).
DST means that some of days have 23 hours and some days have 25 hours. The libraries will help you make the relevant calculations, but now you have to make a decision wether the comparison that you make with "yesterday equivalent" of today's 11:00 is yesterday's 11:00 (23 hours ago) or yesterday's 10:00 (24 hours ago).
For another example, accounting of hours worked - you may have a person that has worked 25 hours in a single day, such events break some systems.