How should detergent be added for heavily soiled laundry versus normally soiled laundry?

For normally soiled laundry, add all the detergent according to the manufacturer's instructions into compartment II of the detergent drawer without selecting the Prewash option. For heavily soiled laundry, select the Prewash option and add one quarter of the recommended detergent amount to compartment I and three quarters to compartment II. (Page 12)