Sample Type (Core Services)
Defines the evaluation of an expression over a time range.
Sampling / evaluation is done based on the archive events of all attributes used in the expression. The expression is evaluated at each of the timestamps of these retrieved events. This sampling algorithm is sometimes referred to as natural or event-based.
Sampling / evaluation is done based on a passed expression interval. This is sometimes referred to as evenly-spaced evaluation. This option is only supported for PI Points on PI Data Archive version 3.4 and above.