## 5.4.3.1 General

When accessing aggregated data using the HistoryRead or the CreateMonitoredItems Service, the following rules are used to handle specific Aggregate use cases.

If ProcessingInterval is 0, the Server shall create one Aggregate value for the entire time range. This allows Aggregates over large periods of time. A value with a timestamp equal to endTime will be excluded from that Aggregate, just as it would be excluded from an interval with that ending time. If the ProcessingInterval of 0 is passed in the MonitoredItemFilter it shall be revised to a suitable non-zero value.

The timestamp returned with the Aggregate shall be the time at the beginning of the interval, except where the Aggregate specifies a different timestamp.

If a requested timestamp is set to anything but the source timestamp the operation shall return the Bad_TimestampToReturnInvalid StatusCode. If a requested timestamp is not supported in any other way for a HistoricalDataNode, the operation shall return the Bad_TimestampNotSupported StatusCode. For MonitoredItem the Server shall not return past data if a requested timestamp is not supported by the history collection.

## 5.4.3.2.1 General

StatusCodes for an Aggregate value shall take into account the values used to calculate them. In addition, the configuration parameters PercentDataGood and PercentDataBad allow the client to control how this calculation is done if supported by the Server.

If an Aggregate operates on raw values (e.g. Average) the calculation is done by counting values. If an Aggregate operates on raw values but can also return a Bounding Value then the Bounding Values are included in the count when computing the StatusCode. If an Aggregate does any sort of a time weighted calculation (e.g. TimeAverage or TimeAverage2) then the StatusCode calculation shall also be time weighted.

For purposes of calculating time weighted StatusCodes each interval shall be divided into regions of Good or Bad data. Creating these regions requires that the bounding values be calculated for each interval and the type of bounding value depends on the Aggregate.

If TreatUncertainAsBad = False then Uncertain regions are included with the Good regions when calculating the above ratios, if the TreatUncertainAsBad = True then the Uncertain regions are included as Bad regions. The StatusCode of the value is still treated as Uncertain when the StatusCode for the result is calculated. If no Bad regions are in the interval then the StatusCode for the interval is Good. For any intervals containing regions where the StatusCodes are Bad, the total duration of all Bad regions is calculated and divided by the width of the interval. The resulting ratio is multiplied by 100 and compared to the PercentDataBad parameter. The StatusCode for the interval is Bad if the ratio is greater than or equal to the PercentDataBad parameter. For any interval which is not Bad, the total duration of all Good regions is then calculated and divided by the width of the interval. The resulting ratio is multiplied by 100 and compared to the PercentDataGood parameter. The StatusCode for the interval is Good if the ratio is greater than or equal to the PercentDataGood parameter. If for an interval neither ratio applies then that interval is Uncertain_DataSubNormal.

If there is no data in the interval and the interval is inside the range [start of data, end of data] and the Aggregate return data type is raw data type then the StatusCodes for the interval will be Bad_NoData unless an alternate status code is defined for a specific Aggregate.

The width of an interval is the ProcessingInterval unless it is a partial interval (i.e. has the Partial bit set). In these cases, the width is the time used when calculating the partial interval.

Subclauses 5.4.3.2.2 and 5.4.3.2.3 include diagrams that illustrate a request and data series. The colour of the time axis indicates the status for different regions. Red indicates Bad, green indicates Good and orange indicates Uncertain. These examples assume TreatUncertainAsBad = False.

## 5.4.3.2.2 Sloped Interpolation and Simple Bounding Values

Figure 2 illustrates a data series for Variable with Stepped = False and an Aggregate that uses Simple Bounding Values. The request being processed has a Start Time that falls before the first point in the series and an End Time that does not fall on an integer multiple of the ProcessingInterval.

Figure 2 – Variable with Stepped = False and Simple Bounding Values

The first interval has four regions:

• the period before the first data point;
• the period between the first and second where SlopedInterpolation can be used;
• the period between the second and third point where SteppedInterpolation is used;
• the period after the Bad point where no data exists. A region is Uncertain if a region ends in a Bad or Uuncertain value and SlopedInterpolation is used. The end point has no effect on the region if SteppedInterpolation is used.

The second interval has three regions:

• the period before the first Good data point where no data exists;
• the period between the first and second where SlopedInterpolation can be used;
• the period between the second point and the bound calculated with SlopedInterpolation. The third interval has three regions:

• the period between the simple bound and the first data point;
• the period between the first point and an interpolated point that falls on the end time;
• the period after the end time which is ignored. This is a partial region and the data after the end time is not used, however, if sloped interpolation is used and the point after the endpoint is Uncertain then the region between the last point and the end time will be Uncertain.

## 5.4.3.2.3 Stepped Interpolation and Interpolated Bounding Values

Figure 3 illustrates a data series for Variable with Stepped = True and an Aggregate that uses Interpolated Bounding Values. The request being processed has a Start Time that falls before the first point in the series and an End Time that does not fall on an integer multiple of the ProcessingInterval.

Figure 3 – Variable with Stepped = True and Interpolated Bounding Values

The first interval has three regions:

• the period before the first data point;
• the period between the first and second where SteppedInterpolation is used;
• the period between the second and the interpolated end bound. The Bad point is ignored because of the interpolated end bound but this does create Uncertain regions. If SlopedInterpolation was used the Uncertain region would start at the second point. In this case, it only starts when the first Bad value is ignored.

The second interval has three regions:

• the period between the start bound and the first data point;
• the period between the first and second where SteppedInterpolation is used;
• the period between the second and the interpolated end bound. The third interval has three regions:

• the period between the interpolated bound and the first data point;
• the period between the first point and an interpolated point that falls on the end time;
• the period after the end time which is ignored. This is a partial region and the data after the end time is not used.

## 5.4.3.3 Description

Subclause 5.4.3.3 deals with Aggregate specific characteristics and behaviour that is specific to a particular Aggregate.

Each subclause has a table which formally expresses the Aggregate behaviour (including any exceptions). The meaning of each of the fields in the table is described in Table 14.

Description of Table 14:

• The first column is the common name for the item.
• The second column includes a description of the item and a list of the valid selections with for the item including a description of each selection.
• The second part of the table describes how the status associated with the Aggregate calculation is computed.
• The last part of the table lists what behaviour is expected from the Aggregate for some common special cases. These behaviours require text descriptions so there is no list of valid selections.

Table 14 – Aggregate table description

Aggregate Characteristics
Type The type of Aggregate.
<Interpolated
Calculated Raw>

Interpolated: See definition for Interpolated.
Calculated: Computed from defined calculation.
Raw: Selects a raw value from within an interval.
Data Type The data type of the result.
<Double
Int32 Same as Source>
Use Bounds How the Aggregate deals with bounds.
<None
Interpolated Simple>

None: Bounds do not apply to the Aggregate.
Interpolated: Uses Interpolated Bounds.
Simple: Uses Simple Bounds.
Timestamp What is the time stamp of the resulting Aggregate value:
<startTime
endTime Raw>

startTime: The time at the start of the interval.
endTime: The time at the end of the interval.
Raw: The time associated with a value in the interval.

Status Code Calculations
Calculation Method How the status code is calculated:
<PercentValues
PercentTime Custom>

PercentValues: Based on percentage of value counts.
PercentTime: Based on percentage of time interval.
Custom: Specific to the Aggregate (description included).
Partial For partial intervals does the Aggregate set this bit
<Set Sometimes
Not Set>

It may also describe any special cases for setting this bit

Calculated Describes the usage of the calculated bit.
<Set Always
Set Sometimes Not Set>

Set Always: The bit is always set.
Set Sometimes: The bit is sometimes set (describes when).
Not Set: The bit is never set.
Interpolated Describes the usage of the interpolated bit.
<Set Always
Set Sometimes Not Set>

Set Always: The bit is always set.
Set Sometimes: The bit is sometimes set (describes when).
Not Set: The bit is never set.
Raw Describes the usage of the Raw bit.
<Set Always
Set Sometimes Not Set>

Set Always: The bit is always set.
Set Sometimes: The bit is sometimes set (describes when).
Not Set: The bit is never set.
Multi Value Describes the usage of the multi value bit.
<Set Sometimes
Not Set>

Set Sometimes: The bit is used (see OPC 10000-11).
Not Set: The bit is never set.

Status Code Common Special Cases
Before Start of Data If the entire interval is before the start of data.
After End of Data If the entire interval is after the end of data (as determined by the Historian).
Start Bound Not Found If the starting bound is not found for the earliest interval and it is not partial, then what, if any, special processing should be done.
End Bound Not Found If the ending bound is not found for the latest interval and it is not partial, then what, if any, special processing should be done.
Bound Bad If the Bounding value is Bad, then what, if any, special processing should be done.
Bound Uncertain If the Bounding value is uncertain, then what, if any, special processing should be done.

## 5.4.3.4 Interpolative

The Interpolative Aggregate defined in Table 15 returns the Interpolated Bounding Value (see 3.1.8) for the startTime of each interval.

When searching for Good values before or after the bounding value, the time period searched is Server specific, but the Server should search a time range which is at least the size of the ProcessingInterval.

Table 15 – Interpolative Aggregate summary

Interpolated Aggregate Characteristics
Type Interpolated
Data Type Same as Source
Use Bounds Interpolated
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Good if no Bad values skipped and Good values are used, Uncertain if Bad values skipped or if Uncertain values are used. If no starting value then Bad_NoData. See description of Interpolated Bounds (see 3.1.8) for more details
Partial bit Not Set
Calculated bit Not Set
Interpolated bit Set Sometimes
Always set except for when the Raw bit is set
Raw bit Set Sometimes
If a value exists with the exact time of interval Start
Multi Value bit Not Set

Status Code Common Special Cases
Before Start of Data Return Bad_NoData
After End of Data Return extrapolated value (see 3.1.8) (sloped or stepped according to settings)
Status code is Uncertain_DataSubNormal.
Bound Bad Does not return a Bad bound except as noted above
Bound Uncertain Returned Uncertain_DataSubNormal if any Bad value(s) was/were skipped to calculate the bounding value.

## 5.4.3.5 Average

The Average Aggregate defined in Table 16 adds up the values of all Good Raw data for each interval, and divides the sum by the number of Good values. If any non-Good values are ignored in the computation, the Aggregate StatusCode will be determined using the StatusCode Calculation (see 5.3). This Aggregate is not time based so the PercentGood/PercentBad applies to the number of values in the interval.

Table 16 – Average Aggregate summary

Average Aggregate Characteristics
Type Calculated
Data Type Double
Use Bounds None
Timestamp StartTime

Status Code Calculations
Calculation Method PercentValues
Partial Not Set
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Bounds not used
No End Bound Bounds not used
Bound Uncertain Bounds not used

## 5.4.3.6 TimeAverage

The TimeAverage Aggregate defined in Table 17 uses Interpolated Bounding Values (see 3.1.8) to find the value of a point at the beginning and end of an interval. Starting at the starting bounding value a straight line is drawn between each value in the interval ending at the ending bounding value (see examples for illustrations). The area under the lines is divided by the length of the ProcessingInterval to yield the average. Note that this calculation always uses a sloped line between points; TimeAverage2 uses a stepped or sloped line depending on the value of the Stepped Property for the Variable.

If one or more Bad Values exist in the interval then they are omitted from the calculation and the StatusCode is set to Uncertain_DataSubNormal. Sloped lines are drawn between the Good values when calculating the area.

The time resolution used in this calculation is Server specific.

Table 17 – TimeAverage Aggregate summary

TimeAverage Aggregate Characteristics
Type Calculated
Data Type Double
Use Bounds Interpolated
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Good if no Bad values skipped and Good values are used, Uncertain if Bad values are skipped or if Uncertain values are used
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
After End of Data Value extrapolated, Uncertain status
No Start Bound Calculate Partial Interval
No End Bound Extrapolate data, Uncertain status
Bound Uncertain NA

## 5.4.3.7 TimeAverage2

The TimeAverage2 Aggregate defined in Table 18 uses Simple Bounding Values (see 3.1.9) to find the value of a point at the beginning and end of an interval. Starting at the starting bounding value a straight line is drawn between each value in the interval ending at the ending bounding value (see examples for illustrations). The area under the lines is divided by the length of the ProcessingInterval to yield the average. Note that this calculation uses a stepped or sloped line depending on what the value of the Stepped Property for the Variable; TimeAverage always uses a sloped line between points.

The time resolution used in this calculation is Server specific.

If any non-Good data exists in the interval, this data is omitted from the calculation and the time interval is reduced by the duration of the non-Good data; i.e. if a value was Bad for 1 minute in a 5-minute interval then the TimeAverage2 would be the area under the 4-minute period of Good values divided by 4 minutes. If a sub-interval ends at a Bad value then only the Good starting value is used to calculate the area of sub-interval preceding the Bad value.

The Aggregate StatusCode will be determined using the StatusCode Calculation (see 5.3).

Table 18 – TimeAverage2 Aggregate summary

TimeAverage2 Aggregate Characteristics
Type Calculated
Data Type Double
Use Bounds Simple
Timestamp StartTime

Status Code Calculations
Calculation Method PercentTime
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Bound is Bad_NoData and treated as any other Bad value in the interval
No End Bound Bound is Bad_NoData and treated as any other Bad value in the interval
Bound Uncertain Treated as any other Uncertain value in the interval

## 5.4.3.8 Total

The Total Aggregate defined in Table 19 performs the following calculation for each interval:

Total = TimeAverage x ProcessingInterval (seconds)

where: TimeAverage is the result from the TimeAverage Aggregate, using the ProcessingInterval supplied to the Total call.

The resulting units would be normalized to seconds, i.e. [TimeAverage Units] x seconds.

The Aggregate StatusCode will be determined using the StatusCode Calculation (see 5.3).

Table 19 – Total Aggregate summary

Total Aggregate Characteristics
Type Calculated
Data Type Double
Use Bounds Interpolated
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Good if no Bad values are skipped and Good values are used, Uncertain if Bad values are skipped or if Uncertain values are used
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
After End of Data Value extrapolated, Uncertain status
No Start Bound Calculate Partial Interval
No End Bound Extrapolate data, Uncertain status
Bound Uncertain NA

## 5.4.3.9 Total2

The Total2 Aggregate defined in Table 20 performs the following calculation for each interval:

Total2 = TimeAverage2 x ProcessingInterval of Good data (seconds)

where TimeAverage2 is the result from the TimeAverage2 Aggregate, using the ProcessingInterval supplied to the Total2 call.

The interval of Good data is the sum of all sub-intervals where non-Bad data exists; i.e. if a value was Bad for 1 minute in a 5-minute interval then the interval of Good data would be the 4-minute period.

The resulting units would be normalized to seconds, i.e. [TimeAverage2 Units] x seconds.

The Aggregate StatusCode will be determined using the StatusCode Calculation (see 5.3).

Table 20 – Total2 Aggregate summary

Total2 Aggregate Characteristics
Type Calculated
Data Type Double
Use Bounds Simple
Timestamp StartTime

Status Code Calculations
Calculation Method PercentTime
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Value for Bound is Bad_NoData and is treated like any other Bad quality value in the calculation (ignored)
No End Bound Value for Bound is Bad_NoData and is treated like any other Bad quality value in the calculation (ignored)
Bound Bad Value is treated like any other Bad quality value in the calculation (ignored)
Bound Uncertain Value is treated like any other non-Good quality value in the calculation (ignored)

## 5.4.3.10 Minimum

The Minimum Aggregate defined in Table 21 retrieves the minimum Good raw value within the interval, and returns that value with the timestamp at the start of the interval. Note that if the same minimum exists at more than one timestamp the MultipleValues bit is set.

Unless otherwise indicated, StatusCodes are Good, Calculated. If the minimum value is on the start time the status code will be Good, Raw. If only Bad quality values are available then the status is returned as Bad_NoData.

The timestamp of the Aggregate will always be the start of the interval for every ProcessingInterval.

Table 21 – Minimum Aggregate summary

Minimum Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds None
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
If no Bad values then the Status is Good. If Bad values exist then the Status is Uncertain_SubNormal. If an Uncertain value is less than the minimum Good value the Status is Uncertain_SubNormal.
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Sometimes
If the Minimum value is not on the StartTime of the interval or if the Status was set to Uncertain_SubNormal because of non-Good values in the interval
Interpolated Not Set
Raw Set Sometimes
If Minimum value is on the StartTime of the interval
Multi Value Set Sometimes
If multiple Good values exist with the Minimum value

Status Code Common Special Cases
No Start Bound Not Applicable
No End Bound Not Applicable
Bound Uncertain Not Applicable

## 5.4.3.11 Maximum

The Maximum Aggregate defined in Table 22 retrieves the maximum Good raw value within the interval, and returns that value with the timestamp at the start of the interval. Note that if the same maximum exists at more than one timestamp the MultipleValues bit is set.

Unless otherwise indicated, StatusCodes are Good, Calculated. If the minimum value is on the interval start time the status code will be Good, Raw. If only Bad quality values are available then the status is returned as Bad_NoData.

The timestamp of the Aggregate will always be the start of the interval for every ProcessingInterval.

Table 22 – Maximum Aggregate summary

Maximum Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds None
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
If no Bad values then the Status is Good. If Bad values exist then the Status is Uncertain_SubNormal. If an Uncertain value is greater than the maximum Good value the Status is Uncertain_SubNormal
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Sometimes
If the Maximum value is not on the startTime of the interval or if the Status was set to Uncertain_SubNormal because of non-Good values in the interval
Interpolated Not Set
Raw Set Sometimes
If Maximum value is on the startTime of the interval
Multi Value Set Sometimes
If multiple Good values exist with the Maximum value

Status Code Common Special Cases
No Start Bound Not Applicable
No End Bound Not Applicable
Bound Uncertain Not Applicable

## 5.4.3.12 MinimumActualTime

The MinimumActualTime Aggregate defined in Table 23 retrieves the minimum Good raw value within the interval, and returns that value with the timestamp at which that value occurs. Note that if the same minimum exists at more than one timestamp, the oldest one is retrieved and the Aggregate Bits are set to MultipleValues.

Table 23 – MinimumActualTime Aggregate summary

MinimumActualTime Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds None
Timestamp Time of Minimum

Status Code Calculations
Calculation Method Custom
If no Bad values then the Status is Good. If Bad values exist then the Status is Uncertain_SubNormal. If an Uncertain value is less than the minimum Good value the Status is Uncertain_SubNormal
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Sometimes
If the Status was set to Uncertain_SubNormal because of non-Good values in the interval
Interpolated Not Set
Raw Set Sometimes
If a Good minimum value is returned
Multi Value Set Sometimes
If multiple Good values exist with the Minimum value

Status Code Common Special Cases
No Start Bound Not Applicable
No End Bound Not Applicable
Bound Uncertain Not Applicable

## 5.4.3.13 MaximumActualTime

The MaximumActualTime Aggregate defined in Table 24 is the same as the MinimumActualTime Aggregate, except that the value is the maximum raw value within the interval. Note that if the same maximum exists at more than one timestamp, the oldest one is retrieved and the Aggregate Bits are set to MultipleValues.

Table 24 – MaximumActualTime Aggregate summary

MaximumActualTime Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds None
Timestamp Time of Maximum

Status Code Calculations
Calculation Method Custom
If no Bad values then the Status is Good. If Bad values exist then the Status is Uncertain_SubNormal. If an Uncertain value is greater than the maximum Good value the Status is Uncertain_SubNormal
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Sometimes
If the Status was set to Uncertain_SubNormal because of non-Good values in the interval
Interpolated Not Set
Raw Set Sometimes
If a Good maximum value is returned
Multi Value Set Sometimes
If multiple Good values exist with the maximum value

Status Code Common Special Cases
No Start Bound Not Applicable
No End Bound Not Applicable
Bound Uncertain Not Applicable

## 5.4.3.14 Range

The Range Aggregate defined in Table 25 finds the difference between the maximum and minimum Good raw values in the interval. If only one Good value exists in the interval, the range is zero. Note that the range is always zero or positive. If non-Good values are ignored when finding the minimum or maximum values or if Bad values exist then the status is Uncertain_DataSubNormal.

Table 25 – Range Aggregate summary

Range Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds None
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
If no Bad values then the Status is Good. If Bad values exist then the Status is Uncertain_SubNormal. If an Uncertain value is greater than the maximum or less than the minimum Good value the Status is Uncertain_SubNormal
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Not Applicable
No End Bound Not Applicable
Bound Uncertain Not Applicable

## 5.4.3.15 Minimum2

The Minimum2 Aggregate defined in Table 26 retrieves the minimum Good value for each interval as defined for Minimum except that Simple Bounding Values are included. The Simple Bounding Values for the interval are found according to the definition of Simple Bounding Values (see 3.1.9). Any Bad values are ignored in the computation. The Aggregate StatusCode will be determined using the StatusCode Calculation (see 5.3) for time based Aggregates. If a bounding value is returned then the status will indicate, Raw, Calculated or Interpolated.

If TreatUncertainAsBad is false and an Uncertain raw value is the minimum then that Uncertain value is used. Uncertain values are ignored otherwise.

If sloped interpolation is used and the End bound is the minimum value then End bound is used as the Minimum with the timestamp set to the startTime of the interval. The End bound is ignored in all other cases.

Table 26 – Minimum2 Aggregate summary

Minimum2 Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds Simple
Timestamp StartTime

Status Code Calculations
Calculation Method PercentTime
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Sometimes
Set unless the StartBound is the Minimum
Interpolated Set Sometimes
If an Interpolated bound is the Minimum
Raw Set Sometimes
If a raw value is the Minimum.
Multi Value Set Sometimes
If more than one Good values exist with the same

Status Code Common Special Cases
No Start Bound Treat the beginning value as Bad_NoData and compute the Aggregate
No End Bound Treat the ending value as Bad_NoData and compute the Aggregate
Bound Bad Use as value and compute the Aggregate as defined
Bound Uncertain Use as value and compute the Aggregate as defined

## 5.4.3.16 Maximum2

The Maximum2 Aggregate defined in Table 27 retrieves the maximum Good value for each interval as defined for Maximum except that Simple Bounding Values are included. The Simple Bounding Values for the interval are found according to the definition of Simple Bounding Values (see 3.1.9). Any Bad values are ignored in the computation. The Aggregate StatusCode will be determined using the StatusCode Calculation (see 5.3) for time based Aggregates. If a bounding value is returned then the status will indicate, Raw, Calculated or Interpolated.

If TreatUncertainAsBad is false and an Uncertain raw value is the maximum then that Uncertain value is used. Uncertain values are ignored otherwise.

If sloped interpolation is used and the End bound is the maximum value then End bound is used as the maximum with the timestamp set to the startTime of the interval. The End bound is ignored in all other cases.

Table 27 – Maximum2 Aggregate summary

Maximum2 Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds Simple
Timestamp StartTime

Status Code Calculations
Calculation Method PercentTime
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Sometimes
Set unless the StartBound is the Maximum
Interpolated Set Sometimes
If an Interpolated bound is the Maximum
Raw Set Sometimes
If a raw value is the Maximum.
Multi Value Set Sometimes
If more than one Good values exist with the same

Status Code Common Special Cases
No Start Bound Treat the beginning value as Bad_NoData and compute the Aggregate
No End Bound Treat the ending value as Bad_NoData and compute the Aggregate
Bound Bad Use as value and compute the Aggregate as defined
Bound Uncertain Use as value and compute the Aggregate as defined

## 5.4.3.17 MinimumActualTime2

The MinimumActualTime2 Aggregate defined in Table 28 retrieves the minimum Good value for each interval as defined for MinimumActualTime except that Simple Bounding Values are included. The Simple Bounding Values for the interval are found according to the definition of Simple Bounding Values (see 3.1.9). Any Bad values are ignored in the computation. The Aggregate StatusCode will be determined using the StatusCode Calculation (see 5.3) for time based Aggregates. If a bounding value is returned then the status will indicate, Raw, Calculated or Interpolated.

If TreatUncertainAsBad is false and an Uncertain raw value is the minimum then that Uncertain value is used. Uncertain values are ignored otherwise.

If sloped interpolation is used and the End bound is the minimum value then End bound is used as the minimum with the timestamp set to the EffectiveEndTime of the interval. The End bound is ignored in all other cases.

Table 28 – MinimumActualTime2 Aggregate summary

MinumumActualTime2 Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds Simple
Timestamp Time of minimum

Status Code Calculations
Calculation Method PercentTime
Partial Set Sometimes
If an interval is not a complete interval
Calculated Not Set
Interpolated Set Sometimes
If an Interpolated bound is the Minimum
Raw Set Sometimes
If a raw value is the Minimum
Multi Value Set Sometimes
If more than one Good values exist with the same value

Status Code Common Special Cases
No Start Bound Treat the beginning value as Bad_NoData and compute the Aggregate
No End Bound Treat the ending value as Bad_NoData and compute the Aggregate
Bound Bad Use as value and compute the Aggregate as defined
Bound Uncertain Use as value and compute the Aggregate as defined

## 5.4.3.18 MaximumActualTime2

The MaximumActualTime2 Aggregate defined in Table 29 retrieves the maximum Good value for each interval as defined for MaximumActualTime except that Simple Bounding Values are included. The Simple Bounding Values for the interval are found according to the definition of Simple Bounding Values (see 3.1.9). Any Bad values are ignored in the computation. The Aggregate StatusCode will be determined using the StatusCode Calculation (see 5.3) for time based Aggregates. If a bounding value is returned then the status will indicate, Raw, Calculated or Interpolated.

If TreatUncertainAsBad is false and an Uncertain raw value is the maximum then that Uncertain value is used. Uncertain values are ignored otherwise.

If sloped interpolation is used and the End bound is the maximum value then End bound is used as the maximum with the timestamp set to the EffectiveEndTime of the interval. The End bound is ignored in all other cases.

Table 29 – MaximumActualTime2 Aggregate summary

MaximumActualTime2 Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds Simple
Timestamp Time of maximum

Status Code Calculations
Calculation Method PercentTime
Partial Set Sometimes
If an interval is not a complete interval
Calculated Not Set
Interpolated Set Sometimes
If an Interpolated bound is the Maximum
Raw Set Sometimes
If a raw value is the Maximum
Multi Value Set Sometimes
If more than one value is equal to the Maximum

Status Code Common Special Cases
No Start Bound Treat the beginning value as Bad_NoData and compute the Aggregate
No End Bound Treat the ending value as Bad_NoData and compute the Aggregate
Bound Bad Use as value and compute the Aggregate as defined
Bound Uncertain Use as value and compute the Aggregate as defined

## 5.4.3.19 Range2

The Range2 Aggregate defined in Table 30 finds the difference between the maximum and minimum values in the interval as returned by the Minimum2 and Maximum2 Aggregates. Note that the range is always zero or positive.

Table 30 – Range2 Aggregate summary

Range2 Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds Simple (used in Minimum2 and Maximum2 calculations)
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
If Minimum2 or Maximum2 are Bad then the status is Bad_NoData. If Minimum2 or Maximum2 are Uncertain then the status is Uncertain_DataSubNormal. Good otherwise
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Handled by Minimum2 and Maximum2
No End Bound Handled by Minimum2 and Maximum2
Bound Bad Handled by Minimum2 and Maximum2
Bound Uncertain Handled by Minimum2 and Maximum2

## 5.4.3.20 AnnotationCount

The AnnotationCount Aggregate defined in Table 31 returns a count of all Annotations in the interval.

The StatusCodes are Good, Calculated.

Table 31 – AnnotationCount Aggregate summary

AnnotationCount Aggregate Characteristics
Type Calculated
Data Type Int32 (negative values are not allowed)
Use Bounds None
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Good unless the interval is before the start of data or after the end of data
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Does not apply
No End Bound Does not apply
Bound Uncertain Does not apply

## 5.4.3.21 Count

The Count Aggregate defined in Table 32 retrieves a count of all the raw values within an interval. If one or more raw values are non-Good, they are not included in the count, and the Aggregate StatusCode is determined using the StatusCode Calculation (see 5.4.3) for non-time based Aggregates. If no Good data exists for an interval, the count is zero.

Unless otherwise indicated, StatusCodes are Good, Calculated.

Table 32 – Count Aggregate summary

Count Aggregate Characteristics
Type Calculated
Data Type Int32 (negative values are not allowed)
Use Bounds None
Timestamp StartTime

Status Code Calculations
Calculation Method PercentValues
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Does not apply
No End Bound Does not apply
Bound Uncertain Does not apply

## 5.4.3.22 DurationInStateZero

The DurationInStateZero Aggregate defined in Table 33 returns the time Duration during the interval that the Variable was in the zero state. The Simple Bounding Values for the interval are used to determine initial value (start time < end time) or ending value (if start time > end time). If one or more raw values are non-Good, they are not included in the Duration, and the Aggregate StatusCode is determined using the StatusCode Calculation (see 5.3) for time based Aggregates. Duration is in milliseconds. Unless otherwise indicated, StatusCodes are Good, Calculated.

Table 33 – DurationInStateZero Aggregate summary

DurationInStateZero Aggregate Characteristics
Type Calculated
Data Type Duration
Use Bounds Simple
Timestamp StartTime

Status Code Calculations
Calculation Method PercentTime
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Treat the beginning value as Bad_NoData and compute the Aggregate
No End Bound Treat the ending value as Bad_NoData and compute the Aggregate
Bound Bad Use as value and compute the Aggregate as defined
Bound Uncertain Use as value and compute the Aggregate as defined

## 5.4.3.23 DurationInStateNonZero

The DurationInStateNonZero Aggregate defined in Table 34 returns the time Duration during the interval that the Variable was in the one state. The Simple Bounding Values for the interval are used to determine initial value (start time < end time) or ending value (if start time > end time). If one or more raw values are non-Good, they are not included in the Duration, and the Aggregate StatusCode is determined using the StatusCode Calculation (see 5.3) for time based Aggregates.

Duration is in milliseconds. Unless otherwise indicated, StatusCodes are Good, Calculated.

Table 34 – DurationInStateNonZero Aggregate Summary

DurationInStateNonZero Aggregate Characteristics
Type Calculated
Data Type Duration
Use Bounds Simple
Timestamp StartTime

Status Code Calculations
Calculation Method PercentTime
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Treat the beginning value as Bad_NoData and compute the Aggregate
No End Bound Treat the ending value as Bad_NoData and compute the Aggregate
Bound Bad Use as value and compute the Aggregate as defined
Bound Uncertain Use as value and compute the Aggregate as defined

## 5.4.3.24 NumberOfTransitions

The NumberOfTransitions Aggregate defined in Table 35 returns a count of the number of transition the Variable had during the interval. If one or more raw values are Bad, they are not included in the count, and the Aggregate StatusCode is determined using the StatusCode Calculation (see 5.3) for non-time based Aggregates.

The earliest transition shall be calculated by comparing the earliest non-Bad value in the interval to the previous non-Bad value. A transition occurred if no previous non-Bad value exists or if the earliest non-Bad value is different. The endTime is not considered part of the interval, so a transition occurring at the endTime is not included.

Unless otherwise indicated, StatusCodes are Good, Calculated.

Table 35 – NumberOfTransitions Aggregate summary

NumberOfTransitions Aggregate Characteristics
Type Calculated
Data Type Int32 (negative values are not allowed)
Use Bounds Custom, a non-Bad value prior to the interval is used
Timestamp StartTime

Status Code Calculations
Calculation Method PercentValues
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Treat the beginning value as Bad_NoData and compute the Aggregate
No End Bound Treat the ending value as Bad_NoData and compute the Aggregate
Bound Bad Use as value and compute the Aggregate as defined
Bound Uncertain Use as value and compute the Aggregate as defined

## 5.4.3.25 Start

The Start Aggregate defined in Table 36 retrieves the earliest raw value within the interval, and returns that value and status with the timestamp at which that value occurs. If no values are in the interval then the StatusCode is Bad_NoData.

Table 36 – Start Aggregate summary

Start Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds None
Timestamp Time of Raw Value

Status Code Calculations
Calculation Method Custom
The raw value status is returned
Partial Set Sometimes
If an interval is not a complete interval
Calculated Not Set
Interpolated Not Set
Raw Always
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Does not apply
No End Bound Does not apply
Bound Uncertain Does not apply

## 5.4.3.26 End

The End Aggregate defined in Table 37 retrieves the latest raw value within the interval, and returns that value and status with the timestamp at which that value occurs. If no values are in the interval then the StatusCode is Bad_NoData.

Table 37 – End Aggregate summary

End Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds None
Timestamp Time of Raw Value

Status Code Calculations
Calculation Method Custom
The raw value status is returned
Partial Set Sometimes
If an interval is not a complete interval
Calculated Not Set
Interpolated Not Set
Raw Always
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Does not apply
No End Bound Does not apply
Bound Uncertain Does not apply

## 5.4.3.27 Delta

The Delta Aggregate defined in Table 38 retrieves the difference between the earliest and latest Good raw values in the interval. The Aggregate is negative if the latest value is less than the earliest value. The status is Uncertain_DataSubNormal if non-Good values are skipped while looking for the first or last values. The status is Good otherwise. The status is Bad_NoData if no Good raw values exist.

Table 38 – Delta Aggregate summary

Delta Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds None
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Uncertain_DataSubNormal   if non-Good values are skipped while looking for the first or last values
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Always
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Does not apply
No End Bound Does not apply
Bound Uncertain Does not apply

## 5.4.3.28 StartBound

The StartBound Aggregate defined in Table 39 returns the value and status at the StartTime for the interval by calculating the Simple Bounding Values for the interval (see 3.1.9).

Table 39 – StartBound Aggregate summary

StartBound Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds Simple
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
The status of the start bound.
Partial Set Sometimes
If an interval is not a complete interval
Calculated Not Set
Interpolated Set Sometimes
If the bound is interpolated
Raw Set Sometimes
If a value exists at the start time
Multi Value Not Set

Status Code Common Special Cases
No End Bound Does not apply
Bound Uncertain Same as bound

## 5.4.3.29 EndBound

The EndBound Aggregate defined in Table 40 returns the value and status at the EndTime for the interval by calculating the Simple Bounding Values for the interval (see 3.1.9).

The timestamp returned is always the start of the interval and Calculated bit is set.

Table 40 – EndBound Aggregate summary

EndBound Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds Simple
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
The status of the end bound.
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound Does not apply
Bound Uncertain Same as bound

## 5.4.3.30 DeltaBounds

The DeltaBounds Aggregate defined in Table 41 returns the difference between the StartBound and the EndBound Aggregates with the exception that both the start and end shall be Good. If the end value is less than the start value, the result will be negative. If the end value is the same as the start value the result will be zero. If the end value is greater than the start value, the result will be positive. If one or both values are Bad the return status will be Bad_NoData. If one or both values are Uncertain the status will be Uncertain_DataSubNormal.

Table 41 – DeltaBounds Aggregate summary

DeltaBounds Aggregate Characteristics
Type Calculated
Data Type Same as Source
Use Bounds Simple
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Good if both bounds are Good
Uncertain_DataSubNormal   if either bound is uncertain
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
Bound Uncertain Uncertain_DataSubNormal

## 5.4.3.31 DurationGood

The DurationGood Aggregate defined in Table 42 divides the interval into regions of Good and non-Good data. Each region starts with a data point in the interval. If that data point is Good the region is Good. The Aggregate is the sum of the duration of all Good regions expressed in milliseconds.

The status of the first region is determined by finding the first data point at or before the start of the interval. If no value exists, the first region is Bad.

Each Aggregate is returned with timestamp of the start of the interval. StatusCodes are Good, Calculated.

Table 42 – DurationGood Aggregate summary

DurationGood Aggregate Characteristics
Type Calculated
Data Type Duration
Use Bounds Uses status of bounding value
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
StatusCode   is always Good, Calculated
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound No special handing required
No End Bound No special handing required
Bound Bad No special handing required
Bound Uncertain No special handing required

The DurationBad Aggregate defined in Table 43 divides the interval into regions of Bad and non-Bad data. Each region starts with a data point in the interval. If that data point is Bad the region is Bad. The Aggregate is the sum of the duration of all Bad regions expressed in milliseconds.

The status of the first region is determined by finding the first data point at or before the start of the interval. If no value exists, the first region is Bad.

Each Aggregate is returned with timestamp of the start of the interval. StatusCodes are Good, Calculated.

Table 43 – DurationBad Aggregate summary

Type Calculated
Data Type Duration
Use Bounds Uses status of bounding value
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
StatusCode   is always Good, Calculated
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound No special handing required
No End Bound No special handing required
Bound Bad No special handing required
Bound Uncertain No special handing required

## 5.4.3.33 PercentGood

The PercentGood Aggregate defined in Table 44 performs the following calculation:

PercentGood = DurationGood / ProcessingInterval x 100

where:

DurationGood is the result from the DurationGood *Aggregate*, calculated using the *ProcessingInterval* supplied to *PercentGood* call.

*ProcessingInterval* is the duration of interval.


If the last interval is a partial interval then the duration of the partial interval is used in the calculation. Each Aggregate is returned with timestamp of the start of the interval. StatusCodes are Good, Calculated.

Table 44 – PercentGood Aggregate summary

PercentGood Aggregate Characteristics
Type Calculated
Data Type Double (percent)
Use Bounds Simple (used in DurationGood calculation)
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Always Good
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound No special handing required
No End Bound No special handing required
Bound Bad No special handing required
Bound Uncertain No special handing required

The PercentBad Aggregate defined in Table 45 performs the following calculation:

where:

DurationBad is the result from the DurationBad *Aggregate*, calculated using the *ProcessingInterval* supplied to *PercentBad* call.

*ProcessingInterval* is the duration of interval.


If the last interval is a partial interval then the duration of the partial interval is used in the calculation. Each Aggregate is returned with timestamp of the start of the interval. StatusCodes are Good, Calculated.

Table 45 – PercentBad Aggregate summary

Type Calculated
Data Type Double (percent)
Use Bounds Simple (used in DurationBad calculation)
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Always Good.
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound No special handing required
No End Bound No special handing required
Bound Bad No special handing required
Bound Uncertain No special handing required

## 5.4.3.35 WorstQuality

The WorstQuality Aggregate defined in Table 46 returns the worst status of the raw values in the interval where a Bad status is worse than Uncertain, which is worse than Good. No distinction is made between the specific reasons for the status.

If multiple values exist with the worst quality but different StatusCodes then the StatusCode of the first value is returned and the MultipleValues bit is set.

This Aggregate returns the worst StatusCode as the value of the Aggregate.

The timestamp is always the start of the interval. The StatusCodes are Good, Calculated.

Table 46 – WorstQuality Aggregate summary

WorstQuality Aggregate Characteristics
Type Calculated
Data Type StatusCode
Use Bounds None
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Always Good
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Used

Status Code Common Special Cases
No Start Bound No special handing required
No End Bound No special handing required
Bound Bad No special handing required
Bound Uncertain No special handing required

## 5.4.3.36 WorstQuality2

The WorstQuality2 Aggregate defined in Table 47 returns the worst status of the raw values in the interval where a Bad status is worse than Uncertain, which is worse than Good. No distinction is made between the specific reasons for the status.

The start bound calculated using Simple Bounding Values (see 3.1.9) is always included when determining the worst quality.

If multiple values exist with the worst quality but different StatusCodes then the StatusCode of the first value is returned and the MultipleValues bit is set.

This Aggregate returns the worst StatusCode as the value of the Aggregate.

The timestamp is always the start of the interval. The StatusCodes are Good, Calculated.

Table 47 – WorstQuality2 Aggregate summary

WorstQuality2 Aggregate Characteristics
Type Calculated
Data Type Status Code
Use Bounds Simple
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Always Good
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Used

Status Code Common Special Cases
No Start Bound No special handing required
No End Bound No special handing required
Bound Bad No special handing required
Bound Uncertain No special handing required

## 5.4.3.37 StandardDeviationSample

The StandardDeviationSample Aggregate defined in Table 48 uses the formula:

Figure 4 – StandardDeviation for Sample Formula

where X is each Good raw value in the interval, Avg(X) is the average of the Good raw values, and n is the number of Good raw values in the interval.

For every interval where n = 1, a value of 0 is returned.

If any non-Good values were ignored, the Aggregate quality is uncertain/subnormal.

All interval Aggregates return timestamp of the start of the interval. Unless otherwise indicated, qualities are Good, Calculated.

This calculation is for a sample population where the calculation is done on a subset of the full set of data. Use StandardDeviationPopulation to calculate the standard deviation of a full set of data (see 5.4.3.39). An example would be when the underlying data is sampled from the data source versus stored on an exception basis.

Table 48 – StandardDeviationSample Aggregate summary

StandardDeviationSample Aggregate Characteristics
Type Calculated
Data Type Status Code
Use Bounds None
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Always Good
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound No special handing required
No End Bound No special handing required
Bound Bad No special handing required
Bound Uncertain No special handing required

## 5.4.3.38 VarianceSample

The VarianceSample Aggregate defined in Table 49 retrieves the square of the standard deviation. Its behaviour is the same as the StandardDeviationSample Aggregate. Unless otherwise indicated, qualities are Good, Calculated.

This calculation is for a sample population where the calculation is done on a subset of the full population. Use VariancePopulation to calculate the variance of a full set of data (5.4.3.40).

Table 49 – VarianceSample Aggregate summary

VarianceSample Aggregate Characteristics
Type Calculated
Data Type Status Code
Use Bounds None
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Always Good
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound No special handing required
No End Bound No special handing required
Bound Bad No special handing required
Bound Uncertain No special handing required

## 5.4.3.39 StandardDeviationPopulation

The StandardDeviation Population Aggregate defined in Table 50 uses the formula:

Figure 5 – StandandDeviation for Population Formula

where X is each Good raw value in the interval, Avg(X) is the average of the Good raw values, and n is the number of Good raw values in the interval.

For every interval where n = 1, a value of 0 is returned.

If any non-Good values were ignored, the Aggregate quality is uncertain/subnormal.

All interval Aggregates return timestamp of the start of the interval. Unless otherwise indicated, qualities are Good, Calculated.

This calculation is for a full population where the calculation is done on the full set of data. Use StandardDeviationSample to calculate the standard deviation of a subset of the full population (5.4.3.37). An example would be when the underlying data is collected on an exception basis versus sampled from the data source.

Table 50 – StandardDeviationPopulation Aggregate summary

StandardDeviationPopulation Aggregate Characteristics
Type Calculated
Data Type Status Code
Use Bounds None
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Always Good
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases
No Start Bound No special handing required
No End Bound No special handing required
Bound Bad No special handing required
Bound Uncertain No special handing required

## 5.4.3.40 VariancePopulation

The VariancePopulation Aggregate defined in Table 51 retrieves the square of the standard deviation. Its behaviour is the same as the StandardDeviationPopulation Aggregate. Unless otherwise indicated, qualities are Good, Calculated.

This calculation is for a full population where the calculation is done on the full set of data. Use VarianceSample to calculate the variance of a subset of the full population (5.4.3.38).

Table 51 – VariancePopulation Aggregate summary

VariancePopulation Aggregate Characteristics
Type Calculated
Data Type Status Code
Use Bounds None
Timestamp StartTime

Status Code Calculations
Calculation Method Custom
Always Good
Partial Set Sometimes
If an interval is not a complete interval
Calculated Set Always
Interpolated Not Set
Raw Not Set
Multi Value Not Set

Status Code Common Special Cases