Returned values for non-valid start times

One example of a non-valid query start time is a start time that is earlier than the start time of the first history block. For delta retrieval, the first row returned will be NULL. The timestamp will be that of the query start time. The next row returned will be timestamped at the start of the history block and have the following attributes:

For cyclic retrieval, NULL will be returned for data values that occur before the start of the history block.

Another non-valid start time is a start time that is later than the current time of the AVEVA Historian computer. For delta retrieval, a single NULL value will be returned. For cyclic retrieval, a NULL will be returned for each data value requested.