Banks in Northern Ireland can be part of either the British or the Irish clearing system, depending on their country of registration. The BBAN, whose format is decided by the national banking community, includes the domestic bank account number, branch identifier and potentially routing information, the only restrictions being that it must be of fixed length and that only case-insensitive alphanumeric characters are used.
To overcome these difficulties, the European Committee for Banking Standards (ECBS) developed the IBAN which was later adopted as an international standard under ISO 13616:1997. The sort code, which is a six-digit number, is usually formatted as three pairs of numbers, for example 12-34-56. Although there is a strong correlation between BIC Codes and sort codes, sort codes are not explicitly encoded into BIC codes (although they are encoded into IBANs).