Also do not use the same character repeated in a "long" sequence. I hate this with IBANs. Too often there's something like '000000' right in the middle of an IB

Also do not use the same character repeated in a "long" sequence. I hate this with IBANs. Too often there's something like '000000' right in the middle of an IBAN and in case copy and paste is not possible I end up counting the number of zeroes at least thrice. Groups of four characters separated by spaces would help in this case but that's another topic.