Or Search as follows.
If the bank includes Particulars, Reference, Code, and related-party bank account columns in the bank account statement file, make sure these fields are mapped to the related payment reconciliation fields correctly.
If you select the UPPERCASE rule on the Code column, when the bank statement file is imported in the "Bank Account Reconciliation" page, the text in this column will be converted to uppercase.
Furthermore, if you choose to apply the transformation rule in the Data Exchange Definition field mapping, it will be applied on all of the statement lines.
You can choose too apply transformation rules only when matching the statement lines for more flexibility. For instance, if you want to convert the Code to UPPERCASE only when matched to a customer, transformation rule should not be applied here; it should be defined on the Matching Rules.
You can create a Transformation Rule to correct a possible mistake on a Customer's payment references and apply it to Automatic Matching Rules. Here is an example of correcting a reference entered as the letter C and letter O rather than the number 0 (zero) for customer numbers starting with a C and followed by 5 numbers.
We will transform a reference entered as the letter C and letter O rather than the number 0 (zero).
See more details on standard Business Central Data Exchange Definitions and Transformation Rules at https://docs.microsoft.com/en-nz/dynamics365/business-central/across-how-to-set-up-data-exchange-definitions