OID4VCI: OPTIONAL. String containing guidance for the Holder of the Wallet on how to obtain the Transaction Code, e.g., describing over which communication channel it is delivered.
OID4VCI: OPTIONAL. String specifying the input character set. Possible values are numeric (only digits) and text (any characters). The default is numeric.
OID4VCI: OPTIONAL. Integer specifying the length of the Transaction Code. This helps the Wallet to render the input screen and improve the user experience.