It is an international bank account ID by the look…93 is Switzerland's country ID so chances are Q is letting the owner of a Swiss Bank Account know that he knows.
OK withdrawing this - I'm digging and the facts I stated about Country codes etc aren't correct.
Will come back if anything checks out.
That's where I was going Anon but IBAN does not appear to support the dk characters at the end IF that is an IBAN number…..