The DataType CDTDateTime is a subtype of DateTime that defines CCTS DateTime. The DateTime identifies a date and time of day to various common resolutions: year, month, week, day, hour, minute, second, and fraction of second from CCTS and is used to represent a Gregorian calendar date with UTC time.
Table 25 - CDTDateTime Definition
Subtype of the UtcTime defined in OPC 10000-3
The Timezone can be used to indicate the time zone associated with the data source. The UtcTime value is in GMT and does not have a time zone factor applied. This parameter is provided to allow a client to display the provided time in the time zone that was associated with to original value.
The DaylightSavings can be used to indicate daylights saving if DaylightSavings was in effect when for the given DateTime. The UtcTime value is in GMT and does not have a Timezone factor applied. This parameter is provided to allow a client to display the provided time with the daylight savings time adjustment that was associated with to original value.