Calling this function returns the time difference between two events. The user supplies two WHERE clauses to mark these events. When dragging a Delta_T element into a variable, the following tree element is created.
Variable Creation > Input > Variables: SQL Elements pane - Aggregation > Time Series > Delta_T
A SQL Text element containing a WHERE clause (including the word WHERE) can be moved over the (empty-Starting SQL Condition) and (empty-Ending SQL Condition) branches of the tree.