Business hour means an hour between 9 a.m. and 5 p.m., during a weekday (Monday through Friday), excluding Federal holidays. Business hour also may include, at the seller's option, a prescriber's regular business hours on Saturdays, provided that the seller has actual knowledge of these hours. Business hour shall be determined based on the time zone of the prescriber.
16 CFR § 315.2
For purposes of this part, the following definitions shall apply: