When you select Delivery reliability, you can enter an allowance of "plus days delayed" or "minus days early" under Allowance for on-time deliveries. They can be shown in days or weeks, depending on the period format that you selected under Format. It is this allowance, together with the type of delivery period that you have chosen to compare with, that determines whether the subcontracting arrivals are delayed, delivered early or within the approved allowance limits.
You can enter default values here. The default values are entered under the heading Supplier Rating under the Purchase tab in the Settings procedure.