These fields define effective time for the Price List. They are very much used by companies which do Last-Minute Sales.
Example:
A company created a promotion for the date 20/09/03, from 09:00 to 10:00.
The field Initial Time must contain 09:00 and field Final Time must contain 10:00 for this promotion.
Sales made on 10:01 or after that cannot participate in this Price List promotion.