 There are also code sharing arrangements between airlines and railway companies, formally known as air-rail alliances, and commonly marketed as "Rail & Fly" due to the popularity of the Deutsche Bahn codeshare with many airlines.They involve some integration of both types of transport, e.g., in finding the fastest connection and allowing the transfer between plane and train using a single ticket.This allows passengers to book a whole journey at the same time, often for a discounted price compared to separate tickets.