The Historical Access Event model extends the standard type model by defining the HistoricalEventConfigurationType. This Object defines the general characteristics of a Node that defines the historical configuration of any HistoricalEventNode that is defined to contain history. It is formally defined in Table 11.

Instances of this type shall be referenced by a HistoricalEventNode using the HasHistoricalConfiguration ReferenceType where the source node is the HistoricalEventNode and the destination node is the instance.

Table 11 – HistoricalEventConfigurationType definition

Attribute	Value
BrowseName	HistoricalEventConfigurationType
IsAbstract	False
References	NodeClass	BrowseName	DataType	TypeDefinition	ModellingRule
HasComponent	Object	EventTypes	--	FolderType	Mandatory
HasProperty	Variable	StartOfArchive	UtcTime	PropertyType	Optional
HasProperty	Variable	StartOfOnlineArchive	UtcTime	PropertyType	Optional
ConformanceUnits
Historical Access Events

EventTypes is an entry point to browse to all EventTypes that can be stored by the Historian. For all EventTypes listed in this folder, all mandatory items in the listed type shall be capable of being stored as part of the Event history. It is recommended that all optional properties that are supported by the EventType can also be stored as part of the Event history.

The StartOfArchive Variable specifies the date before which there is no Event data in the archive either online or offline.

The StartOfOnlineArchive Variable specifies the date of the earliest Event data in the online archive.