IbanNet.Extensions.Bban

While IbanNet performs Mod-97 check digit validation on all IBAN's as defined by the IBAN standard, it does not validate check digits of the Basic Bank Account Number (BBAN) section of an IBAN. Since there is no standard for national bank accounts and as there are many different check digit algorithm variations, it was decided not to include this functionality in the core IbanNet package.

There is an extension package for IbanNet available in a separate GitHub repository with validation rules for BBAN check digits: IbanNet.Extensions.Bban. It is however still in an experimental stage. If you wish to contribute to improve BBAN check digit validation, please go ahead and check it out.