Airlines must use the full 10-digit license plate number for each checked bag, especially on interline (connecting) journeys. This was mandated by IATA policy to avoid confusion. IATA Resolution 751 (2012) requires that interline checked baggage be tagged with all three components of the license plate (the leading digit, the 3-digit issuer code, and the 6-digit serial) and that this full 10-digit number be used in all baggage messaging without change (iata.org). For example, one industry white paper warns that limiting the leading digit (to just 0–2) has caused duplicate tag numbers, so it urges airlines to use all digits 0–9 in that first position (iata.org). In other words, airlines should issue license plate tags from 0000000000 up to 9999999999 (in practice via valid leading digit rules) so no two bags share the same number.
Each element of the 10-digit plate has a prescribed meaning under IATA standards. The leading digit is set according to IATA Resolution 740b: “0” is used only for interline baggage, “1” for fallback tags, “2” for expedited service tags, and any digit 3–9 may be used for any bag (iata.org). This allows airlines to extend their tag numbering. Digits 2–4 of the license plate are the carrier’s three-digit baggage issuer code (assigned by IATA per Resolution 769). The final six digits (positions 5–10) are the serial number generated by the airline’s departure control system when the bag is accepted (iata.org). For example, an airline with code 220 could issue a tag 0220 208212: here “0” (leading) means interline bag, “220” is the carrier code, and “208212” is the unique sequence.
Once assigned, the 10-digit license plate number must remain with that bag. Airlines are instructed never to strip or change the plate (even if a bag is re-routed) (iata.org). All baggage records, messages, and handling instructions reference this exact number. This consistency is critical: the license plate number acts as the “index” or key into all baggage information systems. For example, IATA explains that the license plate number “acts as a key to access the data exchanged in Baggage Information Messages” (linking the physical bag to its tracking data) (iata.org). In practice, this means every airport baggage system, whether online or between partners, uses the same 10-digit tag number to identify the bag. In short, the 10-digit license plate is the bag’s unique identity code, and industry rules insist it be used fully and consistently from check-in to claim (iata.org).
