Interval unit is hours

If the interval unit for a calendar frequency is set to hours (enumeration value of 2), and if the offset start and the offset start unit configured for this frequency is not null, then the first sample for a day is offset from the midnight of that day. This offset is generated using the value in the offset_start and offset_start_unit configured for that frequency. If the interval time between samples goes past the end of that day (that is, 11:59:59pm), then the first sample for the following day is again offset from the midnight (12:00am) of the following day.