Here is the quick note for Banking Details for Supplier in Release 12, which can be assigned at the following four levels:
- Address-Operating Unit
New accounts can be created using existing bank and branch details or new bank/branches can also be entered.
Banking Details page to define the bank accounts used for making payments to suppliers.
You can select the name and number of the bank account from the list of values that includes all active supplier type bank accounts or you can create a new bank account. For each supplier and supplier site that has bank account assignments, you must designate a primary bank account. The primary bank account is used by Payables as a default when you pay this supplier electronically.You may override the default if necessary.
You can also do setup for bank accounts for a supplier can also be setup from iSupplier portal
Using iSupplier Portal, suppliers can access their banking information and, if given the appropriate security privilege, make changes to the details. The buyer administrator can either approve the account or set the status to Verify. You can use the Verify status while you prenote the account or perform other activities for verifying an account with your bank.
You can find more details for supplier bank here .
- R12 Supplier Bank - Techno Functional Guide 
- R12 : Bank & Trading Community Architecture(TCA) 
- R12 : EBS Banking Model in demanding and Changing World 
- Welcome to R12 Account Payable 
- A bit on SEPA - IBAN & BIC