Artikel 21

The benefit of the provisions of Article 20 shall not be confined to transport based on single contracts. It shall extend equally to transport made up of successive stages by rail, by sea or by any other mode of transport traversing the territory of more than one Contracting State and regulated by separate contracts, subject to the fulfilment of the following conditions:
Each of the successive contracts must specify the initial source and final destination of the consignment; during the whole duration of carriage the goods must remain under the supervision of the carriers and must be forwarded by each carrier to his successor direct and without delay other than that necessary for the completion of the transport operations and the Customs, octroi, police or other administrative formalities.