how to know if my sales invoice has a credit or debit memo?

Dear Experts

  Please tell me how we can track if a sales invoice has a credit or debit memo? Which table can i find this?

We have a report of sales values for line itemwise. After doing VFRB the original sales value should get added or deducted as  in case of debit memo or credit memo in my report. But how do i tell my ababper if my sales order or invoice has a credit memo or debit memo?

Regards

yezdevan