Validates an IBAN: country prefix, length, segment-by-segment structure and the ISO 7064 MOD 97-10 check digits, recomputing the correct ones when they are wrong. Checked against the SWIFT IBAN Registry, which also yields bank and branch identifiers and names territories sharing a prefix (Jersey uses GB). Reports every check with status, not only failures, and states what it does not check: existence, bank name, national BBAN check digits. No outbound request.