Clearing/ Matching

Question

Hello SAP Gurus',
Need some clarification here.  I am familiar with clearing rules:  In this activity, you enter the criteria for grouping the open items of an account for automatic clearing. The program clears open items of a group if the balance in local and foreign currency is zero. 
However, what if I want matching documents say invoices and credit memo's but they don't net to zero?  What is this called?  Matching?  I want to create rules to associate items by fields like in clearing rules but will associate the credits and the debits.  I do not want netting leaving one line item with a balance but I would like to see for example a partial payment and then a credit memo comes in later and I would like to see the credit memo applied to that partial payment.
Many thanks!
POINTS AWARDED

Answer 1

Thank you Nimit but what if the amounts do not clear?  Is there a way around it if the reference if not on the offsetting document?
The situation I am thinking about is payment A comes in and is a partial payment against invoice A.  Payment A remains open with the invoice open as well linked to the payment.  Then later, a credit memo comes in for the difference.  I want it to clear automatically.
Another scenario, I receive an advance payment and it finds a noted item on account.  What happens to the noted item when the payment matches?  The noted item is not an accounting document.  Then, an invoice via the interface comes in later, I want the payment to clear that invoice however we the user or the customer does not know what the invoice number would be because it isn't created yet.  I was going to do it by matching the information in the assignment field on the payment which would match a field in the invoice?  Good idea or is there a better one.
Many thanks!
POINTS AWARDED