We are using

AFValuesPlotValues(AFTimeRangetimeRange, intintervals, UOMdesiredUOM)

to retrieve values for our trend plots. the AFSDK reference says the following:

*For each interval, the data available is examined and significant values are returned. Each interval can produce up to 5 values if they are unique, the value at the beginning of the interval, the value at the end of the interval, the highest value, the lowest value and at most one exceptional point (bad status or digital state).*

The min and max of an interval is clear, but users (business) are now asking how the begin and end value of an interval are defined/calculated. can we assume that the function is using interpolation to get the begin and end values of the end or begin of the interval is in between two archive values?

No interpolation occurs, except on the outer bound of the timeRange passed into PlotValues. Maybe this text may be clearer:

Each interval can produce up to 5 values if they are unique, the first value in the interval, the last value, the highest value, the lowest value and at most one exceptional point (bad status or digital state). If no values occur within the interval, none are produced.Essentially, if the density of the pixels exceeds the density of the data, PlotValues will return the same result as RecordedValues (except potentially at the outer boundaries). If the density of the data exceeds the density of the pixels, data is removed, but only in such a way that there is no visible difference in the resulting plot.