BackTracking

When your Trigger service is started, it may end up being in the middle of an event.

If the trigger condition has already been met when the program starts, the system doesn't have any idea when the event began.

BackTracking tries to fill-in-the-blanks by doing a reverse search through history, looking for the most recent time there was a change in the value of your condition.

If found, it will use that time as the start of your event when the Range function is called.