The Sales & Receivables Setup Table
This field contains the code for the number series that will be used to assign numbers to sales prepayment invoices when they are posted.
You must enter a code in this field if you want to use prepayments for sales.
You can use the same number series for prepayment invoices and regular invoices, or you can use different number series. If you use different series, they must not overlap—there must not be any numbers that exist in both series.