setAlert dates

Regarding date_start and date_end when calling setAlert:
Is this the date range on which we will receive alerts or the date range to filter flights on?

For example there is a flight UAL123 that flies the same route every day. If I have an alert set not using the faFlightId but the ident and date_start/date_end set to today, would that give me alerts for only the flight that takes off today (ie flight where ident is UAL123 and scheduled_departure is within date range) or would it also potentially send me the ‘filed’ alert for UAL123 that flies 2 days from now (ie any alerts generated in date range for flights with ident UAL123)?

The date_start/date_end for alerts refers to the scheduled departure time of the flight, evaluated as local time zone of the departure airport.