Annex A (informative) Client conventions ToC Previous

A.2 Determining the first historical data point ToC Previous

In some cases Servers are required to return the first available data point for a historical Node; Clause A.2 recommends the way that a Client should request this information so that Servers can optimize this call, if desired. Although there are multiple calls that could return the first data value, the recommended practice will be to use the StartOfArchive Property.

If this Property isn’t available then use one of the following queries using ReadRawModifiedDetails parameters:

returnBounds=false

numValuesPerNode=1

startTime=DateTime.MinValue+1 second

endTime= DateTime.MinValue

Or:

returnBounds=false

numValuesPerNode=1

startTime=DateTime.MinValue

endTime= DateTime.MaxValue


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