OPC 10000-4 specifies all Services needed for OPC UA Historical Access. In particular:

• The Browse Service Set or Query Service Set to detect HistoricalNodes and their configuration.
• The HistoryRead and HistoryUpdate Services of the Attribute Service Set to read and update history of HistoricalNodes.

6.2 defines additional codes and rules that apply to the StatusCode when used for HistoricalNodes .

The general structure of the StatusCode is specified in OPC 10000-4. It includes a set of common operational result codes which also apply to historical data and/or Events.

In OPC UA Historical Access the StatusCode is used to indicate the conditions under which a Value or Event was stored, and thereby can be used as an indicator of its usability. Due to the nature of historical data and/or Events, additional information beyond the basic quality and call result code needs to be conveyed to the Client, for example, whether the value is actually stored in the data repository, whether the result was Interpolated, whether all data inputs to a calculation were of good quality, etc.

In the following, Table 17 contains codes with Bad severity indicating a failure; Table 18 contains Good (success) codes.

It is important to note that these are the codes that are specific for OPC UA Historical Access and supplement the codes that apply to all types of data and are therefore defined in OPC 10000-4 , OPC 10000-8 andOPC 10000-13.

Table 17 – Bad operation level result codes

Symbolic Id	Description
Bad_NoData	No data exists for the requested time range or Event filter.
Bad_BoundNotFound	No data found to provide upper or lower bound value.
Bad_BoundNotSupported	Bounding Values are not applicable or the Server has reached its search limit and will not return a bound.
Bad_DataLost	Data is missing due to collection started/stopped/lost.
Bad_DataUnavailable	Expected data is unavailable for the requested time range due to an un-mounted volume, an off-line historical collection, or similar reason for temporary unavailability.
Bad_EntryExists	The data or Event was not successfully inserted because a matching entry exists.
Bad_NoEntryExists	The data or Event was not successfully updated because no matching entry exists.
Bad_TimestampNotSupported	The Client requested history using a TimestampsToReturn the Server does not support (i.e. requested Server Timestamp when Server only supports SourceTimestamp).
Bad_InvalidArgument	One or more arguments are invalid or missing.
Bad_AggregateListMismatch	The list of Aggregates does not have the same length as the list of operations.
Bad_AggregateConfigurationRejected	The Server does not support the specified AggregateConfiguration for the Node.
Bad_AggregateNotSupported	The specified Aggregate is not valid for the specified Node.
Bad_ArgumentsMissing	See OPC 10000-4 for the description of this result code.
Bad_TypeDefinitionInvalid	See OPC 10000-4 for the description of this result code.
Bad_SourceNodeIdInvalid	See OPC 10000-4 for the description of this result code.
Bad_OutOfRange	See OPC 10000-4 for the description of this result code.
Bad_NotSupported	See OPC 10000-4 for the description of this result code.
Bad_IndexRangeInvalid	See OPC 10000-4 for the description of this result code.
Bad_NotWriteable	See OPC 10000-4 for the description of this result code.

Table 18 – Good operation level result codes

Symbolic Id	Description
Good_NoData	No data exists for the requested time range or Event filter.
Good_EntryInserted	The data or Event was successfully inserted into the historical database
Good_EntryReplaced	The data or Event field was successfully replaced in the historical database
Good_DataIgnored	The Event field was ignored and was not inserted into the historical database.

It may be noted that there are both Good and Bad Status codes that deal with cases of no data or missing data. In general Good_NoData is used for cases where no data was found when performing a simple ‘Read’ request. Bad_NoData is used in cases where some action is requested on an interval and no data could be found. The distinction exists if users are attempting an action on a given interval where they would expect data to exist, or would like to be notified that the requested action could not be performed.

Good_NoData is returned for cases such as:

• ReadEvents where startTime =endTime
• ReadEvent data is requested and does not exist
• ReadRaw where data is requested and does not exist

Bad_NoData is returned for cases such as:

• ReadEvent data is requested and underlying historian does not support the requested field
• ReadProcessed where data is requested and does not exist
• Any Delete requests where data does not exist

The above use cases are illustrative examples. Detailed explanations on when each status code is returned are found in 6.4 and 6.7

The StatusCode in addition contains an informational bit called Semantics Changed (see OPC 10000-4).

UA Servers that implement OPC UA Historical Access should not set this bit; rather they should propagate the StatusCode which has been stored in the data repository. The Client should be aware that the returned data values may have this bit set.

The continuationPoint parameter in the HistoryRead Service is used to mark a point from which to continue the read if not all values could be returned in one response. The value is opaque for the Client and is only used to maintain the state information for the Server to continue from. For HistoricalDataNode requests, a Server may use the timestamp of the last returned data item if the timestamp is unique. This can reduce the need in the Server to store state information for the continuation point.

The Client specifies the maximum number of results per operation in the request Message. A Server shall not return more than this number of results but it may return fewer results. The Server allocates a ContinuationPoint if there are more results to return. The Server may return fewer results due to buffer issues or other internal constraints. It may also be required to return a continuationPoint due to HistoryRead parameter constraints. If a request is taking a long time to calculate and is approaching the timeout time, the Server may return partial results with a continuation point. This may be done if the calculation is going to take more time than the Client timeout. In some cases it may take longer than the Client timeout to calculate even one result. Then the Server may return zero results with a continuation point that allows the Server to resume the calculation on the next Client read call. For additional discussions regarding ContinuationPoints and HistoryRead please see the individual extensible HistoryReadDetails parameter in 6.4.

If the Client specifies a ContinuationPoint, then the HistoryReadDetails parameter and the TimestampsToReturn parameter are ignored, because it does not make sense to request different parameters when continuing from a previous call. It is permissible to change the dataEncoding parameter with each request.

If the Client specifies a ContinuationPoint that is no longer valid, then the Server shall return a Bad_ContinuationPointInvalid error.

If the releaseContinuationPoints parameter is set in the request the Server shall not return any data and shall release all ContinuationPoints passed in the request. If the ContinuationPoint for an operation is missing or invalid then the StatusCode for the operation shall be Bad_ContinuationPointInvalid.

The HistoryRead Service defined in OPC 10000-4 can perform several different functions. The HistoryReadDetails parameter is an Extensible Parameter that specifies which function to perform and the details that are specific to that function. See OPC 10000-4 for the definition of Extensible Parameter. Table 19 lists the symbolic names of the valid Extensible Parameter structures. Some structures will perform different functions based on the setting of its associated parameters. For simplicity a functionality of each structure is listed. For example, text such as ‘using the Read modified functionality’ refers to the function the HistoryRead Service performs using the Extensible Parameter structure ReadRawModifiedDetails with the isReadModified Boolean parameter set to TRUE.

Table 19 – HistoryReadDetails parameterTypeIds

Symbolic Name	Functionality	Description
ReadEventDetails	Read event	This structure selects a set of Events from the history database by specifying a filter and a time domain for one or more Objects or Views. See 6.4.2.1. When this parameter is specified the Server returns a HistoryEvent structure for each operation (see 6.5.4).
ReadRawModifiedDetails	Read raw	This structure selects a set of values from the history database by specifying a time domain for one or more Variables. See 6.4.3.1. When this parameter is specified the Server returns a HistoryData structure for each operation (see 6.5.2).
ReadRawModifiedDetails	Read modified	This parameter selects a set of modified values from the history database by specifying a time domain for one or more Variables. See 6.4.3.1. When this parameter is specified the Server returns a HistoryModifiedData structure for each operation (see 6.5.3).
ReadProcessedDetails	Read processed	This structure selects a set of Aggregate values from the history database by specifying a time domain for one or more Variables. See 6.4.4.1. When this parameter is specified the Server returns a HistoryData structure for each operation (see 6.5.2)
ReadAtTimeDetails	Read at time	This structure selects a set of raw or interpolated values from the history database by specifying a series of timestamps for one or more Variables. See 6.4.5.1. When this parameter is specified the Server returns a HistoryData structure for each operation (see Clause 6.5.2).
ReadAnnotationDataDetails	Read Annotation Data	This structure selects a set of Annotation Data from the history database by specifying a series of timestamps for one or more Variables. See 6.4.6.1. When this parameter is specified the Server returns a HistoryAnnotationData structure for each operation (see Clause 6.5.5).

Table 20 defines the ReadEventDetails structure. This parameter is only valid for Objects that have the EventNotifier Attribute set to TRUE (see OPC 10000-3). Two of the three parameters, numValuesPerNode, startTime, and endTime shall be specified.

Table 20 – ReadEventDetails

Name	Type	Description
ReadEventDetails	Structure	Specifies the details used to perform an Event history read.
numValuesPerNode	Counter	The maximum number of values returned for any Node over the time range. If only one time is specified, the time range shall extend to return this number of values. The default value of 0 indicates that there is no maximum.
startTime	UtcTime	Beginning of period to read. The default value of DateTime.MinValue indicates that the startTime is Unspecified.
endTime	UtcTime	End of period to read. The default value of DateTime.MinValue indicates that the endTime is Unspecified.
Filter	EventFilter	A filter used by the Server to determine which HistoricalEventNode should be included. This parameter shall be specified and at least one EventField is required. The EventFilter parameter type is an Extensible parameter type. It is defined and used in the same manner as defined for monitored data items which are specified in OPC 10000-4. This filter also specifies the EventFields that are to be returned as part of the request.

The ReadEventDetails structure is used to read the Events from the history database for the specified time domain for one or more HistoricalEventNodes . The Events are filtered based on the filter structure provided. This filter includes the EventFields that are to be returned. For a complete description of filter refer to OPC 10000-4.

The startTime and endTime are used to filter on the Time field for Events.

The time domain of the request is defined by startTime, endTime, and numValuesPerNode; at least two of these shall be specified. If endTime is less than startTime, or endTime and numValuesPerNode alone are specified then the data will be returned in reverse order with later/newer data provided first as if time were flowing backward. If all three are specified then the call shall return up to numValuesPerNode results going from startTime to endTime, in either ascending or descending order depending on the relative values of startTime and endTime. If numValuesPerNode is 0 then all of the values in the range are returned. The default value is used to indicate when startTime, endTime or numValuesPerNode are not specified.

It is specifically allowed for the startTime and the endTime to be identical. This allows the Client to request the Event at a single instance in time. When the startTime and endTime are identical then time is presumed to be flowing forward. If no data exists at the time specified then the Server shall return the Good_NoData StatusCode.

If a startTime, endTime and numValuesPerNode are all provided, and if more than numValuesPerNode Events exist within that time range for a given Node, then only numValuesPerNode Events per Node are returned along with a ContinuationPoint. When a ContinuationPoint is returned, a Client wanting the next numValuesPerNode values should call HistoryRead again with the continuationPoin t set.

If the request takes a long time to process then the Server can return partial results with a ContinuationPoint. This might be done if the request is going to take more time than the Client timeout hint. It may take longer than the Client timeout hint to retrieve any results. In this case the Server may return zero results with a ContinuationPoint that allows the Server to resume the calculation on the next Client HistoryRead call.

For an interval in which no data exists, the corresponding StatusCode shall be Good_NoData.

The filter parameter is used to determine which historical Events and their corresponding fields are returned. It is possible that the fields of an EventType are available for real time updating, but not available from the historian. In this case a StatusCode value will be returned for any Event field that cannot be returned. The value of the StatusCode shall be Bad_NoData.

If the requested TimestampsToReturn is not supported for a Node then the operation shall return the Bad_TimestampNotSupported StatusCode. When reading Events this only applies to Event fields that are of type DataValue.

Table 21 defines the ReadRawModifiedDetails structure. Two of the three parameters, numValuesPerNode, startTime, and endTime shall be specified.

Table 21 – ReadRawModifiedDetails

Name	Type	Description
ReadRawModifiedDetails	Structure	Specifies the details used to perform a “raw” or “modified” history read.
isReadModified	Boolean	TRUE for Read Modified functionality, FALSE for Read Raw functionality. Default value is FALSE.
startTime	UtcTime	Beginning of period to read. Set to default value of DateTime.MinValue if no specific start time is specified.
endTime	UtcTime	End of period to read. Set to default value of DateTime.MinValue if no specific end time is specified.
numValuesPerNode	Counter	The maximum number of values returned for any Node over the time range. If only one time is specified, the time range shall extend to return this number of values. The default value 0 indicates that there is no maximum.
returnBounds	Boolean	A Boolean parameter with the following values: TRUEBounding Values should be returned FALSEAll other cases

When this structure is used for reading Raw Values (isReadModified is set to FALSE), it reads the values, qualities, and timestamps from the history database for the specified time domain for one or more HistoricalDataNodes . This parameter is intended for use by a Client that wants the actual data saved within the historian. The actual data may be compressed or may be all raw data collected for the item depending on the historian and the storage rules invoked when the item values were saved. When returnBounds is TRUE, the Bounding Values for the time domain are returned. The optional Bounding Values are provided to allow the Client to interpolate values for the start and end times when trending the actual data on a display.

The time domain of the request is defined by startTime, endTime, and numValuesPerNode; at least two of these shall be specified. If endTime is less than startTime, or endTime and numValuesPerNode alone are specified then the data will be returned in reverse order, with later data coming first as if time were flowing backward. If a startTime, endTime and numValuesPerNode are all provided and if more than numValuesPerNode values exist within that time range for a given Node then only numValuesPerNode values per Node shall be returned along with a continuationPoint. When a continuationPoint is returned, a Client wanting the next numValuesPerNode values shall call ReadRaw again with the continuationPoint set. If numValuesPerNode is 0, then all the values in the range are returned. A default value of DateTime.MinValue (see OPC 10000-6) is used to indicate when startTime or endTime is not specified.

It is specifically allowed for the startTime and the endTime to be identical. This allows the Client to request just one value. When the startTime and endTime are identical then time is presumed to be flowing forward. It is specifically not allowed for the Server to return a Bad_InvalidArgument StatusCode if the requested time domain is outside of the Server's range. Such a case shall be treated as an interval in which no data exists.

If the request takes a long time to process then the Server can return partial results with a ContinuationPoint. This might be done if the request is going to take more time than the Client timeout hint. It may take longer than the Client timeout hint to retrieve any results. In this case the Server may return zero results with a ContinuationPoint that allows the Server to resume the calculation on the next Client HistoryRead call.

If Bounding Values are requested and a non-zero numValuesPerNode was specified then any Bounding Values returned are included in the numValuesPerNode count. If numValuesPerNode is 1 then only the start bound is returned (the end bound if the reverse order is needed). If numValuesPerNode is 2 then the start bound and the first data point are returned (the end bound if reverse order is needed). When Bounding Values are requested and no bounding value is found then the corresponding StatusCode entry will be set to Bad_BoundNotFound, a timestamp equal to the start or end time as appropriate, and a value of null. How far back or forward to look in history for Bounding Values is Server dependent.

For an interval in which no data exists, if Bounding Values are not requested, then the corresponding StatusCode shall be Good_NoData. If Bounding Values are requested and one or both exist, then the result code returned is Success and the bounding value(s) are returned.

For cases where there are multiple values for a given timestamp, all but the most recent are considered to be Modified values and the Server shall return the most recent value. If the Server returns a value which hides other values at a timestamp then it shall set the ExtraData bit in the StatusCode associated with that value. If the Server contains additional information regarding a value then the ExtraData bit shall also be set. It indicates that ModifiedValues are available for retrieval, see 6.4.3.3.

If the requested TimestampsToReturn is not supported for a Node, the operation shall return the Bad_TimestampNotSupported StatusCode.

When this structure is used for reading Modified Values (isReadModified is set to TRUE), it reads the modified values, StatusCodes, timestamps, modification type, the user identifier, and the timestamp of the modification from the history database for the specified time domain for one or more HistoricalDataNodes . If there are multiple replaced values the Server shall return all of them. The updateType specifies what value is returned in the modification record. If the updateType is INSERT the value is the new value that was inserted. If the updateType is anything else the value is the old value that was changed. See 6.8 HistoryUpdateDetails parameter for details on what updateTypes are available.

The purpose of this function is to read values from history that have been Modified. The returnBounds parameter shall be set to FALSE for this case, otherwise the Server returns a Bad_InvalidArgument StatusCode.

The domain of the request is defined by startTime, endTime, and numValuesPerNode; at least two of these shall be specified. If endTime is less than startTime, or endTime and numValuesPerNode alone are specified, then the data shall be returned in reverse order with the later data coming first. If all three are specified then the call shall return up to numValuesPerNode results going from StartTime to EndTime, in either ascending or descending order depending on the relative values of StartTime and EndTime. If more than numValuesPerNode values exist within that time range for a given Node then only numValuesPerNode values per Node are returned along with a continuationPoint. When a continuationPoint is returned, a Client wanting the next numValuesPerNode values should call ReadRaw again with the continuationPoint set. If numValuesPerNode is 0 then all of the values in the range are returned. If the Server cannot return all modified values for a given timestamp in a single response then it shall return modified values with the same timestamp in subsequent calls.

If the request takes a long time to process then the Server can return partial results with a ContinuationPoint. This might be done if the request is going to take more time than the Client timeout hint. It may take longer than the Client timeout hint to retrieve any results. In this case the Server may return zero results with a ContinuationPoint that allows the Server to resume the calculation on the next Client HistoryRead call.

If a value has been modified multiple times then all values for the time are returned. This means that a timestamp can appear in the array more than once. The order of the returned values with the same timestamp should be from the most recent to oldest modification timestamp, if startTime is less than or equal to endTime. If endTime is less than startTime, then the order of the returned values will be from the oldest modification timestamp to the most recent. It is Server dependent whether multiple modifications are kept or only the most recent.

A Server does not have to create a modification record for data when it is first added to the historical collection. If it does then it shall set the ExtraData bit and the Client can read the modification record using a ReadModified call. If the data is subsequently modified the Server shall create a second modification record which is returned along with the original modification record whenever a Client uses the ReadModified call if the Server supports multiple modification records per timestamp.

If the requested TimestampsToReturn is not supported for a Node then the operation shall return the Bad_TimestampNotSupported StatusCode.

Table 22 defines the structure of the ReadProcessedDetails structure.

Table 22 – ReadProcessedDetails

Name	Type	Description
ReadProcessedDetails	Structure	Specifies the details used to perform a “processed” history read.
startTime	UtcTime	Beginning of period to read.
endTime	UtcTime	End of period to read.
ProcessingInterval	Duration	Interval between returned Aggregate values. The value 0 indicates that there is no ProcessingInterval defined.
aggregateType[]	NodeId	The NodeId of the HistoryAggregate object that indicates the list of Aggregates to be used when retrieving the processed history. SeeOPC 10000-13 for details.
aggregateConfiguration	Aggregate Configuration	Aggregate configuration structure.
useServerCapabilitiesDefaults	Boolean	As described in OPC 10000-4.
TreatUncertainAsBad	Boolean	As described in OPC 10000-13.
PercentDataBad	Byte	As described in OPC 10000-13.
PercentDataGood	Byte	As described in OPC 10000-13.
UseSlopedExtrapolation	Boolean	As described in OPC 10000-13.

SeeOPC 10000-13 for details on possible NodeId values for the aggregateType parameter.

This structure is used to compute Aggregate values, qualities, and timestamps from data in the history database for the specified time domain for one or more HistoricalDataNodes . The time domain is divided into intervals of duration ProcessingInterval. The specified Aggregate Type is calculated for each interval beginning with startTime by using the data within the next ProcessingInterval.

For example, this function can provide hourly statistics such as Maximum, Minimum, and Average for each item during the specified time domain when ProcessingInterva l is 1 hour.

The domain of the request is defined by startTime, endTime, and ProcessingInterval. All three shall be specified. If endTime is less than startTime then the data shall be returned in reverse order with the later data coming first. If startTime and endTime are the same then the Server shall return Bad_InvalidArgument as there is no meaningful way to interpret such a case. If the ProcessingInteval is specified as 0 then Aggregates shall be calculated using one interval starting at startTime and ending at endTime.

The aggregateType[] parameter allows a Client to request multiple Aggregate calculations per requested NodeId. If multiple Aggregates are requested then a corresponding number of entries are required in the NodesToRead array.

For example, to request Min Aggregate for NodeId FIC101, FIC102, and both Min and Max Aggregates for NodeId FIC103 would require NodeId FIC103 to appear twice in the NodesToRead array request parameter.

aggregateType[]	NodesToRead[]
Min	FIC101
Min	FIC102
Min	FIC103
Max	FIC103

If the array of Aggregates does not match the array of NodesToRead then the Server shall return a StatusCode of Bad_AggregateListMismatch.

The aggregateConfiguration parameter allows a Client to override the Aggregate configuration settings supplied by the AggregateConfiguration Object on a per call basis. SeeOPC 10000-13 for more information on Aggregate configurations. If the Server does not support the ability to override the Aggregate configuration settings then it shall return a StatusCode of Bad_ AggregateConfigurationRejected. If the Aggregate is not valid for the Node then the StatusCode shall be Bad_AggregateNotSupported.

The values used in computing the Aggregate for each interval shall include any value that falls exactly on the timestamp at the beginning of the interval, but shall not include any value that falls directly on the timestamp ending the interval. Thus, each value shall be included only once in the calculation. If the time domain is in reverse order then we consider the later timestamp to be the one beginning the subinterval, and the earlier timestamp to be the one ending it. Note that this means that simply swapping the start and end times will not result in getting the same values back in reverse order as the intervals being requested in the two cases are not the same.

If an Aggregate is taking a long time to calculate then the Server can return partial results with a continuation point. This might be done if the calculation is going to take more time than the Client timeout hint. In some cases it may take longer than the Client timeout hint to calculate even one Aggregate result. Then the Server may return zero results with a continuation point that allows the Server to resume the calculation on the next Client read call.

Refer toOPC 10000-13 for handling of Aggregate specific cases.

Table 23 defines the ReadAtTimeDetails structure.

Table 23 – ReadAtTimeDetails

Name	Type	Description
ReadAtTimeDetails	Structure	Specifies the details used to perform an “at time” history read.
reqTimes []	UtcTime	The entries define the specific timestamps for which values are to be read.
useSimpleBounds	Boolean	Use SimpleBounds to determine the value at the specific timestamp.

The ReadAtTimeDetails structure reads the values and qualities from the history database for the specified timestamps for one or more HistoricalDataNodes . This function is intended to provide values to correlate with other values with a known timestamp. For example, a Client may need to read the values of sensors when lab samples were collected.

The order of the values and qualities returned shall match the order of the timestamps supplied in the request.

When no value exists for a specified timestamp, a value shall be Interpolated from the surrounding values to represent the value at the specified timestamp. The interpolation will follow the same rules as the standard Interpolated Aggregate as outlined inOPC 10000-13.

If the useSimpleBounds flag is True and Interpolation is required then simple bounding values will be used to calculate the data value. If useSimpleBounds is False and Interpolation is required then interpolated bounding values will be used to calculate the data value. SeeOPC 10000-13 for the definition of simple bounding values and interpolated bounding values.

If a value is found for the specified timestamp, then the Server will set the StatusCode InfoBits to be Raw. If the value is Interpolated from the surrounding values, then the Server will set the StatusCode InfoBits to be Interpolated.

If the read request is taking a long time to calculate then the Server may return zero results with a ContinuationPoint that allows the Server to resume the calculation on the next Client HistoryRead call.

If the requested TimestampsToReturn is not supported for a Node, then the operation shall return the Bad_TimestampNotSupported StatusCode.

Table 24 defines the ReadAnnotationDataDetails structure.

Table 24 – ReadAnnotaionDataDetails

Name	Type	Description
ReadAnnotationDataDetails	Structure	Specifies the details used to perform an “at time” history read.
reqTimes []	UtcTime	The entries define the specific timestamps for which values are to be read.

The ReadAnnotationDataDetails structure reads the Annotaion Data from the history database for the specified timestamps for one or more HistoricalDataNodes .

The order of the Annotations Data returned shall match the order of the timestamps supplied in the request.

If Annotation Data is not supported for a HistoricalDataNode then the StatusCode shall be Bad_HistoryOperationUnsupported.

If the read request is taking a long time to calculate then the Server may return zero results with a ContinuationPoint that allows the Server to resume the calculation on the next Client HistoryRead call.

The HistoryRead Service returns different types of data depending on whether the request asked for the value Attribute of a Node or the history Events of a Node. The historyData is an Extensible Parameter whose structure depends on the functions to perform for the HistoryReadDetails parameter. See OPC 10000-4 for details on Extensible Parameters.

Table 25 defines the structure of the HistoryData used for the data to return in a HistoryRead.

Table 25 – HistoryData Details

Name	Type	Description
HistoryData	Structure
dataValues[]	DataValue	An array of values of history data for the Node. The size of the array depends on the requested data parameters.

Table 26 defines the structure of the HistoryModifiedData used for the data to return in a HistoryRead when IsReadModified = True.

Table 26 – HistoryModifiedData Details

Name	Type	Description
HistoryModifiedData	Structure
dataValues[]	DataValue	An array of values of history data for the Node. The size of the array depends on the requested data parameters.
modificationInfos[]	ModificationInfo
modificationTime	UtcTime	The time the modification was made. Support for this field is optional. A null shall be returned if it is not defined.
updateType	HistoryUpdateType	The modification type for the item.
userName	String	The name of the user that made the modification. Support for this field is optional. A null shall be returned if it is not defined.

Table 27 defines the HistoryEvent parameter used for Historical Event reads.

The HistoryEvent defines a table structure that is used to return Event fields to a Historical Read. The structure is in the form of a table consisting of one or more Events, each containing an array of one or more fields. The selection and order of the fields returned for each Event are identical to the selected parameter of the EventFilter.

Table 27 – HistoryEvent Details

Name	Type	Description
Events []	HistoryEventFieldList	The list of Events being delivered.
eventFields []	BaseDataType	List of selected Event fields. This will be a one-to-one match with the fields selected in the EventFilter.

Table 25 defines the structure of the HistoryAnnotationData used for the data to return in a HistoryRead.

It is the same structure used for normal HistoryData.

Table 29 defines the HistoryUpdate enumeration.

Table 29 – HistoryUpdateType Enumeration

Value	Description
INSERT_1	Data was inserted.
REPLACE_2	Data was replaced.
UPDATE_3	Data was inserted or replaced.
DELETE_4	Data was deleted.

Table 30 defines the PerformUpdateType enumeration.

Table 30 – PerformUpdateType Enumeration

Value	Description
INSERT_1	Data was inserted.
REPLACE_2	Data was replaced.
UPDATE_3	Data was inserted or replaced.
REMOVE_4	Data was deleted.

The HistoryUpdate Service defined in OPC 10000-4 can perform several different functions. The historyUpdateDetails parameter is an Extensible Parameter that specifies which function to perform and the details that are specific to that function. See OPC 10000-4 for the definition of Extensible Parameter. Table 31 lists the symbolic names of the valid Extensible Parameter structures. Some structures will perform different functions based on the setting of its associated parameters. For simplicity a functionality of each structure is listed. For example text such as ‘using the Replace data functionality’ refers to the function the HistoryUpdate Service performs using the Extensible Parameter structure UpdateDataDetails with the performInsertReplace enumeration parameter set to REPLACE_2.

Table 31 – HistoryUpdateDetails parameter TypeIds

Symbolic Name	Functionality	Description
UpdateDataDetails	Insert data	This function inserts new values into the history database at the specified timestamps for one or more HistoricalDataNodes . The Variable’s value is represented by a composite value defined by the DataValue data type.
UpdateDataDetails	Replace data	This function replaces existing values into the history database at the specified timestamps for one or more HistoricalDataNodes . The Variable’s value is represented by a composite value defined by the DataValue data type.
UpdateDataDetails	Update data	This function inserts or replaces values into the history database at the specified timestamps for one or more HistoricalDataNodes . The Variable’s value is represented by a composite value defined by the DataValue data type.
UpdateStructureDataDetails	Insert data	This function inserts new Structured History Data or Annotations into the history database at the specified timestamps for one or more HistoricalDataNodes . The Variable’s value is represented by a composite value defined by the DataValue data type.
UpdateStructureDataDetails	Replace data	This function replaces existing Structured History Data or Annotations into the history database at the specified timestamps for one or more HistoricalDataNodes . The Variable’s value is represented by a composite value defined by the DataValue data type.
UpdateStructureDataDetails	Update data	This function inserts or replaces Structured History Data or Annotations into the history database at the specified timestamps for one or more HistoricalDataNodes . The Variable’s value is represented by a composite value defined by the DataValue data type.
UpdateStructureDataDetails	Remove data	This function removes Structured History Data or Annotations from the history database at the specified timestamps for one or more HistoricalDataNodes . The Variable’s value is represented by a composite value defined by the DataValue data type.
UpdateEventDetails	Insert events	This function inserts new Events into the history database for one or more HistoricalEventNodes .
UpdateEventDetails	Replace events	This function replaces values of fields in existing Events into the history database for one or more HistoricalEventNodes .
UpdateEventDetails	Update events	This function inserts new Events or replaces existing Events in the history database for one or more HistoricalEventNodes .
DeleteRawModifiedDetails	Delete raw	This function deletes all values from the history database for the specified time domain for one or more HistoricalDataNodes .
DeleteRawModifiedDetails	Delete modified	Some historians may store multiple values at the same Timestamp. This function will delete specified values and qualities for the specified timestamp for one or more HistoricalDataNodes .
DeleteAtTimeDetails	Delete at time	This function deletes all values in the history database for the specified timestamps for one or more HistoricalDataNodes .
DeleteEventDetails	Delete event	This function deletes Events from the history database for the specified filter for one or more HistoricalEventNodes .

The HistoryUpdate Service is used to update or delete, DataValues, Annotations or Events. For simplicity the term “entry” will be used to mean either DataValue, Annotation, or Event depending on the context in which it is used. Auditing requirements for History Services are described in OPC 10000-4. This description assumes the user issuing the request and the Server that is processing the request support the capability to update entries. See OPC 10000-3 for a description of Attributes that expose the support of Historical Updates.

If the HistoryUpdate Service is called with two or more of DataValues, Events or Annotations in the same call the Server operational limits MaxNodesPerHistoryUpdateData and MaxNodesPerHistoryUpdateEvents (See OPC 10000-5) may be ignored. The Server may return the service result code Bad_TooManyOperations if it is not able to handle the combination of DataValues, Events or Annotations. It is recommended to call the HistoryUpdate Service individually with DataValues, Events or Annotations.

Table 32 defines the UpdateDataDetails structure.

Table 32 – UpdateDataDetails

Name	Type	Description
UpdateDataDetails	Structure	The details for insert, replace, and insert/replace history updates.
nodeId	NodeId	Node id of the Object to be updated.
performInsertReplace	PerformUpdateType	Value determines which action of insert, replace, or update is performed. Value Description INSERT_1 See 6.8.2.2. REPLACE_2 See 6.8.2.3. UPDATE_3 See 6.8.2.4.
updateValues[]	DataValue	New values to be inserted or to replace.

Setting performInsertReplace = INSERT_1 inserts entries into the history database at the specified timestamps for one or more HistoricalDataNodes . If an entry exists at the specified timestamp, then the new entry shall not be inserted; instead the StatusCode shall indicate Bad_EntryExists.

This function is intended to insert new entries at the specified timestamps, e.g., the insertion of lab data to reflect the time of data collection.

If the Time does not fall within range that can be stored then the related operationResults entry shall indicate Bad_OutOfRange.

Setting performInsertReplace = REPLACE_2 replaces entries in the history database at the specified timestamps for one or more HistoricalDataNodes . If no entry exists at the specified timestamp, then the new entry shall not be inserted; otherwise the StatusCode shall indicate Bad_NoEntryExists.

This function is intended to replace existing entries at the specified timestamp, e.g., correct lab data that was improperly processed, but inserted into the history database.

Setting performInsertReplace = UPDATE_3 inserts or replaces entries in the history database for the specified timestamps for one or more HistoricalDataNodes . If the item has an entry at the specified timestamp, then the new entry will replace the old one. If there is no entry at that timestamp, then the function will insert the new data.

A Server can create a modified value for a value being replaced or inserted (see 3.1.6) however it is not required.

This function is intended to unconditionally insert/replace values and qualities, e.g., correction of values for bad sensors.

Good as a StatusCode for an individual entry is allowed when the Server is unable to say whether there was already a value at that timestamp. If the Server can determine whether the new entry replaces an entry that was already there, then it should use Good_EntryInserted or Good_EntryReplaced to return that information.

If the Time does not fall within range that can be stored then the related operationResults entry shall indicate Bad_OutOfRange.

Table 32 defines the UpdateStructureDataDetails structure.

Table 33 – UpdateStructureDataDetails

Name	Type	Description
UpdateStructureDataDetails	Structure	The details for Structured Data History updates.
nodeId	NodeId	Node id of the Object to be updated.
performInsertReplace	PerformUpdateType	Value determines which action of insert, replace, or update is performed. Value Description INSERT_1 See 6.8.3.3. REPLACE_2 See 6.8.3.4. UPDATE_3 See 6.8.3.5. REMOVE_4 See 6.8.3.6.
updateValues[]	DataValue	New values to be inserted, replaced or removed. Such as Annotation data for Annotations.

Structured History Data provides metadata describing an entry in the history database. The Server shall define what uniqueness means for each Structured History Data structure type. For example, a Server may only allow one Annotation per timestamp which means the timestamp is the unique key for the structure. Another Server may allow Annotations to exist per user, so a combination of a username and timestamp may be used as the unique key for the structure. In 6.8.3.3, 6.8.3.4, 6.8.3.5, and 6.8.3.6 the terms ‘Structured History Data exists’ and ‘at the specified parameters’ means a matching entry has been found at the specified timestamp using the Server’s criteria for uniqueness.

In the case where the Client wishes to replace a parameter that is part of the uniqueness criteria, then the resulting StatusCode would be Bad_NoEntryExists. The Client shall remove the existing structure and then Insert the new structure.

Setting performInsertReplace = INSERT_1 inserts Structured History Data such as Annotations into the history database at the specified parameters for one or more Properties of HistoricalDataNodes.

If a Structured History Data entry already exists at the specified parameters the StatusCode shall indicate Bad_EntryExists.

If the Time does not fall within range that can be stored then the related operationResults entry shall indicate Bad_OutOfRange.

Setting performInsertReplace = REPLACE_2 replaces Structured History Data such as Annotations in the history database at the specified parameters for one or more Properties of HistoricalDataNodes.

If a Structured History Data entry does not already exist at the specified parameters, then the StatusCode shall indicate Bad_NoEntryExists.

Setting performInsertReplace = UPDATE_3 inserts or replaces Structured History Data such as Annotations in the history database at the specified parameters for one or more Properties of HistoricalDataNodes.

If a Structure History Data entry already exists at the specified parameters then it is deleted and the value provided by the Client is inserted. If no existing entry exists then the new entry is inserted.

If an existing entry was replaced successfully then the StatusCode shall be Good_EntryReplaced. If a new entry was created the StatusCode shall be Good_EntryInserted. If the Server cannot determine whether it replaced or inserted an entry then the StatusCode shall be Good.

If the Time does not fall within range that can be stored then the related operationResults entry shall indicate Bad_OutOfRange.

Setting performInsertReplace = REMOVE_4 removes Structured History Data such as Annotations from the history database at the specified parameters for one or more Properties of HistoricalDataNodes.

If a Structure History Data entry exists at the specified parameters it is deleted. If Structured History Data does not already exist at the specified parameters, then the StatusCode shall indicate Bad_NoEntryExists.

Table 34 defines the UpdateEventDetails structure.

Table 34 – UpdateEventDetails

Name	Type	Description
UpdateEventDetails	Structure	The details for insert, replace, and insert/replace history Event updates.
nodeId	NodeId	Node id of the Object to be updated.
performInsertReplace	PerformUpdateType	Value determines which action of insert, replace, or update is performed. Value Description INSERT_1 Perform Insert Event (see 6.8.4.2). REPLACE_2 Perform Replace Event (see 6.8.4.3). UPDATE_3 Perform Update Event (see 6.8.4.4). REMOVE_4 Not used.
filter	EventFilter	If the history of Notification conforms to the EventFilter, the history of the Notification is updated.
eventData[]	HistoryEventFieldList	List of Event Notifications to be inserted or updated (see 6.5.4 for HistoryEventFieldList definition).

This function is intended to insert new entries, e.g., backfilling of historical Events.

Setting performInsertReplace = INSERT_1 inserts entries into the Event history database for one or more HistoricalEventNodes. The whereClause parameter of the EventFilter shall be empty. The SelectClause shall as a minimum provide the following Event fields: EventType and Time. It is also recommended that the SourceNode and the SourceName fields are provided. If one of the required fields is not provided then the statusCode shall indicate Bad_ArgumentsMissing. If the historian does not support archiving the specified EventType then the statusCode shall indicate Bad_TypeDefinitionInvalid. If the SourceNode is not a valid source for Events then the related operationResults entry shall indicate Bad_SourceNodeIdInvalid. If the Time does not fall within range that can be stored then the related operationResults entry shall indicate Bad_OutOfRange. If the selectClause does not include fields which are mandatory for the EventType then the statusCode shall indicate Bad_ArgumentsMissing. If the selectClause specifies fields which are not valid for the EventType or cannot be saved by the historian then the related operationResults entry shall indicate Good_DataIgnored. Additional information about the ignored fields shall be provided through DiagnosticInformation related to the operationResults. The symbolicId contains the index of each ignored field separated with a space and the localizedText contains the symbolic names of the ignored fields.

The EventId is a Server generated opaque value and a Client cannot assume that it knows how to create valid EventIds. A Server shall be able to generate an appropriate default value for the EventId field. If a Client does specify the EventId in the selectClause and it matches an existing Event then the statusCode shall indicate Bad_EntryExists. A Client shall use a HistoryRead to discover any automatically generated EventIds.

If any errors occur while processing individual fields then the related operationResults entry shall indicate Bad_InvalidArgument and the invalid fields shall be indicated in the DiagnosticInformation related to the operationResults entry.

The IndexRange parameter of the SimpleAttributeOperand is not valid for insert operations and the StatusCode shall specify Bad_IndexRangeInvalid if one is specified.

A Client may instruct the Server to choose a suitable default value for a field by specifying a value of null. If the Server is not able to select a suitable default then the corresponding entry in the operationResults array for the affected Event shall be Bad_InvalidArgument.

This function is intended to replace fields in existing Event entries, e.g., correct Event data that contained incorrect data due to a bad sensor.

Setting performInsertReplace = REPLACE_2 replaces entries in the Event history database for the specified EventIds for one or more HistoricalEventNodes . The SelectClause parameter of the EventFilter shall specify the EventId Property and the eventData shall contain the EventId which will be used to find the Event to be replaced. If no entry exists matching the specified EventId then no replace operation will be performed; instead the operationResults entry for the eventData entry shall indicate Bad_NoEntryExists. The whereClause parameter of the EventFilter shall be empty.

If the selectClause specifies fields which are not valid for the EventType or cannot be saved or changed by the historian then the operationResults entry for the affected Event shall indicate Good_DataIgnored. Additional information about the ignored fields shall be provided through DiagnosticInformation related to the operationResults. The symbolicId contains the index of each ignored field separated with a space and the localizedText contains the symbolic names of the ignored fields.

If fatal errors occur while processing individual fields then the operationResults entry for the affected Event shall indicate Bad_InvalidArgument and the invalid fields shall be indicated in the DiagnosticInformation related to the operationResults entry.

This function is intended to unconditionally insert/replace Events, e.g., synchronizing a backup Event database.

Setting performInsertReplace = UPDATE_3 inserts or replaces entries in the Event history database for the specified filter for one or more HistoricalEventNodes .

The Server will, based on its own criteria, attempt to determine if the Event already exists; if it does exist then the Event will be deleted and the new Event will be inserted (retaining the EventId). If the EventID was provided then the EventID will be used to determine if the Event already exists. If the Event does not exist then a new Event will be inserted, including the generation of a new EventId.

All of the restrictions, behaviours, and errors specified for the Insert functionality (see 6.8.4.2) also apply to this function.

If an existing Event entry was replaced successfully then the related operationResults entry shall be Good_EntryReplaced. If a new Event entry was created then the related operationResults entry shall be Good_EntryInserted. If the Server cannot determine whether it replaced or inserted an entry then the related operationResults entry shall be Good.

Table 35 defines the DeleteRawModifiedDetails structure.

Table 35 – DeleteRawModifiedDetails

Name	Type	Description
DeleteRawModifiedDetails	Structure	The details for delete raw and delete modified history updates.
nodeId	NodeId	Node id of the Object for which history values are to be deleted.
isDeleteModified	Boolean	TRUE for MODIFIED, FALSE for RAW. Default value is FALSE.
startTime	UtcTime	Beginning of period to be deleted.
endTime	UtcTime	End of period to be deleted.

These functions are intended to be used to delete data that has been accidentally entered into the history database, e.g., deletion of data from a source with incorrect timestamps. Both startTime and endTime shall be defined. The startTime shall be less than the endTime, and values up to but not including the endTime are deleted. It is permissible for startTime = endTime, in which case the value at the startTime is deleted.

Setting isDeleteModified = FALSE deletes all Raw entries from the history database for the specified time domain for one or more HistoricalDataNodes .

If no data is found in the time range for a particular HistoricalDataNode, then the StatusCode for that item is Bad_NoData.

Setting isDeleteModified = TRUE deletes all Modified entries from the history database for the specified time domain for one or more HistoricalDataNodes .

If no data is found in the time range for a particular HistoricalDataNode, then the StatusCode for that item is Bad_NoData.

Table 36 defines the structure of the DeleteAtTimeDetails structure.

Table 36 – DeleteAtTimeDetails

Name	Type	Description
DeleteAtTimeDetails	Structure	The details for delete raw history updates
nodeId	NodeId	Node id of the Object for which history values are to be deleted.
reqTimes []	UtcTime	The entries define the specific timestamps for which values are to be deleted.

The DeleteAtTime structure deletes all raw values, modified values, and annotations in the history database for the specified timestamps for one or more HistoricalDataNodes .

This parameter is intended to be used to delete specific data from the history database, e.g., lab data that is incorrect and cannot be correctly reproduced.

Table 37 defines the structure of the DeleteEventDetails structure.

Table 37 – DeleteEventDetails

Name	Type	Description
DeleteEventDetails	Structure	The details for delete raw and delete modified history updates.
nodeId	NodeId	Node id of the Object for which history values are to be deleted.
eventIds[]	ByteString	An array of EventIds to identify which Events are to be deleted.

The DeleteEventDetails structure deletes all Event entries from the history database matching the EventId for one or more HistoricalEventNodes .

If no Events are found that match the specified filter for a HistoricalEventNode, then the StatusCode for that Node is Bad_NoData.