How to capture bank statement details in external transaction Reference

Summary:

We are importing Brazilian bank statements from Santander bank into Oracle. The statements are in CNAB format and these are being imported via OIC, which is handling the localization process. We have transaction creation rules in place, which would automatically create external transactions based on the transaction code in the bank statement file. User wishes to store a specific tag from the statement file, in the respective external transaction reference field, in Oracle.

For example, transaction code 105, in the statement file has a description tag, which has to be stored in the external transaction Reference field. Is there a way to handle this?