According to the BACnet protocol documentation:

In a BACnet device. A BACnet device can use a DateTime Value object to make any kind of datetime data value accessible to other BACnet devices. The mechanisms by which the value is derived are not visible to the BACnet client. A DateTime Value object is used to represent a single moment in time. In contrast, the DateTime Pattern Value object can be used to represent multiple recurring dates and times. DateTime Value objects may optionally support intrinsic reporting to facilitate the reporting of fault conditions.

Objects of type datetimeValue have the following properties:

•ackedTransitions

•commandTimeArray

•currentCommandPriority

•description

•eventDetectionEnable

•eventEnable

•eventMessageTexts

•eventMessageTextsConfig

•eventState

•eventTimeStamps

•isUtc

•lastCommandTime

•notificationClass

•notifyType

•objectIdentifier

•objectName

•objectType

•outOfService

•presentValue

•priorityArray

•profileLocation

•profileName

•propertyList

•reliability

•reliabilityEvaluationInhibit

•relinquishDefault

•statusFlags

•tags

•valueSource

•valueSourceArray