Also, sort codes for Northern Ireland branches of banks registered in both Northern Ireland and the Republic, are valid, and recognized for use in the Republic. The checksum enables the initiator of any transaction to perform a sanity check of any specified bank account number on their own computer prior to actually initiating a request. All paper instruments presented to the clearinghouse must be MICR-encoded. Since the IBAN error detection uses mod 97, it will trap all such errors.
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