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The vehicleNumber should be the published train number when possible. For buses without unique id:s use the line number, or if the published id:s should be unique then that should be used instead. If the bus needs a unique published id, then use that value. In Samtrafiken’s NeTEx dataset, the value is always found in the ServiceJourney.PublicCode element.
Trains: NeTEx - TrainNumber.ForAdvertisment
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