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• Continuous delivery of data points according to a predefined agreement
• Not only a different container type.  It deals more with the delivery method (constant stream compared to atomic message)
• Does not have a fixed start/end time
• Delivers a stream of Records (or Snapshots)
• + could also deliver side-band information (e.g. Job information)
• Is analogous to the delivery of a Subscription for protocols that support subscriptions.

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DerivedRecord and StatisticalRecord

• This is a record type that does not deliver the original data but something that is calculated from it.
• This is needed only if the requested derived signal is not available already in the VSS signal database.  It is perfectly possible to use VSS to define some derived value already.
  A normal request for that VSS signal would deliver the value, and there is no need to define in our value-measurement protocols how the value is calculated.  It is simply decided by the system that delivers it.   There is already an example of this in VSS today:   Vehicle.AverageSpeed which has the description "Average speed for the current trip".  You could imagine defining another signal named Vehicle.Speed.MonthlyAverage, for example and just fetch it as a normal Record.
• As a complement, a derived record type, such as statistical record, is useful since it can have modifiable parameters such as over which time period is the measurement done.
• Subtypes of this are StatisticalRecord and maybe some others (e.g. mathematical function / curve matching?)
• Further Subtypes of StatisticalRecord:  Average, Median, Max, Min, Histogram, and so on.  

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Examples, in JSON

(Plain) Record:

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