Arrangements between air carriers

20.1 These rules cover transportations, which are carried out in accordance with commercial agreements between air carriers (agreements about joint usage of codes (Codesharing), agreements about mutual acceptance of traffic documents (interline) even if on the ticket another airline is indicated other than the airline that actually performs the transportation.
If there is any such commercial agreement then the airline or its air transportation sales agent has to provide passengers with this information during reservation, regarding which air carrier is contracting and which air carrier is actually performing the transportation. During passenger’s check-in for the flight, this information is given by the air carrier or its authorized handling agent at the airport of departure.
20.2 If a passenger concluded the air transportation agreement with rendering of additional prepaid services, then the air carrier is responsible for rendering such prepaid services.