The Update Stock Levels Based on Sales History section allows you to automatically update your Order Level and Stock Level based on Quantity Sold Sales History, Lead Time, Order Frequency and Safety Stock setup for your Vendors. The Order Frequency, Lead Time and Safety Stock are in Business Days. Business Days are calculated based on the number of days of the week you are open setup in “Location Entry” in SYSTEM MANAGEMENT (10.2.5.1 field 7).