Examples

BD51 SMR — a UK registration plate
M-AB 1234 — a German one
CJ 12 ABC — a Romanian one, told from a British one by its spacing
CSQU 305438 3 10G0 — a shipping container, size code and all
GB29 NWBK 6016 1331 9268 19 — an IBAN
127.0.0.1:53 — an IP endpoint on a reserved address
2001:db8::1 — an IPv6 address from the documentation range
CVE-2014-1266 — a vulnerability identifier
urn:uuid:550e8400-e29b-41d4-a716-446655440000 — a UUID, wearing its URN dressing