How to apply a credit memo (from a legacy system) against an invoice using AutoInvoice: To link the credit to an invoice there are 2 options:
1) Populate REFERENCE_LINE_ID on RA_INTERFACE_LINES_ALL with the CUSTOMER_TRX_LINE_ID of the invoice. or
2) Populate REFERENCE_LINE_ATTRIBUTE1 to 15 with the INTERFACE_LINE_ATTRIBUTE1 to 15 of the invoice.
You also need to populate REFERENCE_LINE_CONTEXT with INTERFACE_LINE_CONTEXT of the invoice. INTERFACE_LINE_CONTEXT and INTERFACE_LINE_ATTRIBUTE1 to 15 are stored in RA_CUSTOMER_TRX_LINES_ALL.
To create an on-account credit (i.e. not linked to an invoice) do not populate REFERENCE_LINE_ID, REFERENCE_LINE_ATTRIBUTES or REFERENCE_LINE_CONTEXT.