I am extracting historical time-series from DSS using the Rest API. What is the role of parameter LookBackPeriod in the Condition, and what influence if any does it have on the extraction time? At the moment we are not passing anything. If I want to get data for the last 5 days or the last 10 years, which value should I use in both cases ? Can it be used with Start/End dates or they are mutually exclusive?