Timestamps are datetime fields that contain the starting time for the metrics contained in the record. To determine the entire range of time encompassed by the data you will need to evaluate the in conjunction with the TimeStamp. Note that all timestamps are in UTC (Universal Coordinated Time) and not in the local time zone.
This timestamp indicates the date and time of January 10, 2008 at 12:00 UTC. If the TimeType field for this record is 2 indicating this is hourly data then this record represents metrics for 12:00 to 13:00 on January 10, 2008.