What storage method can Historian's Discrete and Message tags use for recording?

The correct answer is Delta because this storage method specifically caters to the nature of Discrete and Message tags in a way that optimizes storage space and enhances performance. Delta storage tracks only changes or "deltas" in data values over time instead of continuously recording every single data point. This is particularly beneficial for discrete events, where state changes occur infrequently and directly correlates to a more efficient use of storage. By storing only the differences from the last recorded value, the Delta method minimizes the amount of unnecessary data storage required for unchanging values, making it ideal for event-driven data like that from Discrete and Message tags.

The other methods—Static, Time Series, and Snapshot—do not serve the unique storage requirements of these tag types effectively. Static storage does not account for time-stamped data tracking, which is essential for data analysis. Time Series, while useful for continuous data, isn't as efficient for tags that change state infrequently. Snapshot may capture data at specific intervals but does not optimize storage like Delta does, especially when changes are minimal. Therefore, Delta is the most suitable choice here.