Fare : The online representation of a fare. In case the final product requires the indication of carriers it is obligatory to provide a carrierConstraint in the fare directly that includes the list of all carriers in the includedCarrier list. Whether the carrier must be indicated needs to be derived from the requested total route and the location of the sales points for international sales. Whether the indication of carriers is obligatory is defined in the Convention concerning International Carriage by Rail (COTIF).