The Sales & Receivables Setup Table
This field contains the code for the number series that is used to assign numbers to sales prepayment credit memos when they are posted.
You must enter a code in this field if you want to reverse the posting of a sales prepayment invoice.
You can use the same number series for prepayment credit memos and regular credit memos, 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.