# Three letters have to survive being read upside down > A bag tag's three-letter code has to work for a scanner, a handler and a passenger reading it upside down on a belt, which is why it's the largest thing printed. August 19, 2026 · https://justog.club/stories/luggage-tag-airport-codes A narrow card tag, curled at one end where it's been threaded through a handle. VRN printed large across the middle, a barcode under it, then the routing line: KLD to VRN to ASH. Flight QN 411 sits in smaller type beneath. Three letters have done nearly all the work by the time anyone reads this the whole way through. ## Why is the code the biggest thing printed on a bag tag? Because it's the one part that has to be read correctly by everybody who touches the bag, including a machine. A three-letter code has to work for a sorting belt moving the bag at speed, a handler glancing at it from an angle, and a passenger reading it upside down off a carousel they're leaning over. The same principle that makes [a split-flap board legible across a whole concourse](/stories/departure-board-split-flap) is behind the size here too: there's no clever type treatment that beats simply making the one part everyone needs the largest thing on the card. ## Why isn't the city's actual name printed anywhere on the tag? Because the code already does the city's job, and printing the name as well would only leave more room for the two to disagree. The system runs on the codes, not the names — a sorting belt, a connections board and a handler's manifest all key off VRN, KLD and ASH rather than off whatever a city calls itself, which sidesteps two places sharing a name or one place having several. The tag prints the version the machinery actually reads and drops the one that's only for people. ## What's the routing line actually telling you? The story of the bag, told in the third person, in three words. KLD to VRN to ASH is where the bag started, where it's changing planes, and where it's meant to end up — a whole itinerary compressed into two arrows and nine letters. Everything else on the tag identifies the bag to a machine; the routing line is the one part written for a person, and it's still terse enough to fit on a strip that could get lost in a coat pocket. ## Can I put a real airport's code or a real airline's flight number on this? Not without the airport's or the airline's permission, though the idea of a routing tag isn't anybody's property. A three-letter airport code and an airline's own numbering prefix — the QN in QN 411 — are assigned identities, licensable in the ordinary way if a real one is the point of the shirt. If it isn't, an invented code is usually the better choice anyway: VRN is a place that exists only for the bag it's printed on, which means the routing line can say precisely the trip someone actually took rather than the nearest real approximation of it. ## Does this work for a trip that never went through an actual airport? Yes — the format doesn't care whether the journey was real, only whether the shorthand is consistent with itself. An invented departure code for the place someone grew up, a made-up connection for the city where a couple met, an arrival code standing in for wherever a family gathers each year — the tag reads the same whether the airport exists or not, because nothing on it claims to be issued by a real carrier. The same terse habit shows up on other tickets in this set, including [a ferry's own printed card](/stories/ferry-crossing-timetable), where the shorthand just runs to times instead of letters. ## Isn't a bag tag meant to be thrown away the moment the trip ends? That's exactly why one that survives is worth keeping. A real tag gets cut off at the carousel and binned within the hour — it was never built to last a day past the flight. Printing the design permanently is the same move as [keeping a torn cloakroom ticket](/stories/left-luggage-ticket): the object's whole point was to be temporary, which is precisely what makes a version that doesn't disappear feel like it's keeping something. ## Does it print well? Yes, as two flat colours with the code set large enough to read from across a room. Black on bone keeps the contrast a real tag needs for a scanner, and orange for the routing line separates the machine-facing text from the human-facing one without needing a third ink. The barcode is the one element to simplify rather than reproduce exactly — a handful of bars reads as "barcode" on fabric, where a genuinely scannable one just goes muddy at the weave. ## How do I get one made? Describe the trip at [JustOG](/) — departure, connection, arrival, and the flight number running underneath. Pick a direction, drag the crop frame, see it composited on the real garment, and it's made to order and shipped. Designs other people have published are in the [shop](/shop). Somewhere a belt is still turning with a tag on it nobody's claimed.