I have a regex which extracts German and Austrian IBANs. However, I just realized, that html code sometimes has strange format.
\b(?:DE|AT)(?:\s?[0-9a-zA-Z]){18}(?:(?:\s?[0-9a-zA-Z]){2})?\b
Therefore I have to exclude not valid IBAN matches. In my demo I show examples which show missmatches. How would you exclude this?