Positive Lookbehind(?<=IBAN(?:[:\s]\s|\s[:\s])) IBANthe literal text IBAN (case insensitive) Non-Capturing Group(?:[:\s]\s|\s[:\s]) :the literal : (5810 / 728 / 3A16)
\sa Unicode whitespace character
\sa Unicode whitespace character
\sa Unicode whitespace character
:the literal : (5810 / 728 / 3A16)
\sa Unicode whitespace character
NLthe literal text NL (case insensitive) \s?optionally matches a Unicode whitespace character
\d{2}a Unicode decimal digit, repeated exactly 2 times
\s?optionally matches a Unicode whitespace character
{4}matches exactly 4 characters from the set below:
A-Zone character from A (6510) to Z (9010) (case insensitive)
0the literal 0 (4810 / 608 / 3016)
the literal (3210 / 408 / 2016)
\s?optionally matches a Unicode whitespace character
\d{9,10}a Unicode decimal digit, repeated between 9 and 10 times