The right to carry out transport of goods and persons between two points on the inland waterways covered by the Revised Convention for the navigation on the Rhine is reserved to vessels owned by either nationals of Contracting States of that Convention or Member States of the EU, or companies based on the territory of any of these States, which are owned in majority and controlled by nationals of these States.

"Article 2
The vessels belonging to the navigation of the Rhine and the rafts or wooden trains coming from the Rhine will have the right to choose any route they like when crossing the Netherlands to return from the Rhine to the open sea or to Belgium and vice versa.
If, as a result of natural events or works of art, one of the waterways connecting the open sea at the Rhine by Dordrecht, Rotterdam, Hellevoetsluis and Brielle, became impracticable for navigation, the waterway which would be indicated to Dutch navigation in replacement of the intercepted passage will also be open to navigation by others Riparian states.
Will be considered as belonging to the navigation of the Rhine any boat having the right to fly the flag of one of the Contracting States and can justify this right by means of a document issued by the competent authority.
Article 3
No rights based solely on the fact of navigation may be levied on the ships or their loads no more than on rafts navigating on the Rhine, on its tributaries, in so far as they are located in the territory of the High Contracting Parties, and on the waterways mentioned in article 2.
[...]
Article 4
The vessels belonging to the navigation of the Rhine are authorized to carry out transport of goods and people between two points on the waterways mentioned in the first paragraph of article 3. The other buildings are not authorized to carry out such transport operations only under conditions determined by the Commission Central.
The conditions of transport of goods and people by boats not belonging to not to the navigation of the Rhine, between a place situated on the waterways mentioned above and a place situated on the territory of a third State, are determined in agreements to conclude between the two Parties concerned. The Central Commission is consulted before the conclusion of such agreements. 
As regards the inland waterways mentioned above, national treatment, in all respects, will be granted to vessels belonging to the navigation of the Rhine and to their loads.[...]" (Revised Convention for Rhine Navigation, signed in Mannheim on 17 October 1868, entry into force of the revised version on 14 April 1967, Articles 2, 3 and 4, including amendments brought by Additional Protocol No. 2 of 17 October 1979 [google translation])
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"1. The document referred to in Article 2, paragraph 3, of the Revised Convention for Rhine Navigation, amended by Additional Protocol No. 2, shall be issued by the competent authorities of the State concerned only for a vessel which has a genuine link with that State, the aspects of which shall be determined on the basis of the equality of treatment between Contracting States which shall take the necessary steps to ensure its standard adoption. When the conditions for the issue of this document are no longer met, it shall cease to be valid  and shall then be withdrawn by the authority which issued it.
2. With a view to the development of a common policy for transport and the Rhine regime, the Contracting States shall. be prepared to take the necessary steps to permit the negotiation of such amendments to the revised Convention for Rhine Navigation as might prove necessary with a view to the possible accession of the European Economic Community to the international regulations on the Rhine.
3. With a view to this possible accession, the same treatment accorded to vessels belonging to the Rhine navigation system shall be accorded as soon as this Protocol enters into force to vessels with the right to fly the flag of any state member of the European Community. The same treatment may be accorded by a decision taken pursuant to the procedure of Article II, first paragraph, second sentence, of Additional Protocol No. 2, to vessels flying the flag of another State.[...]" (Protocol of Signature of Additional Protocol No. 2 to the revised Convention for Rhine Navigation, signed in Strasbourg on 17 October 1979, entry into force on 1 February 1985, Numbers 1, 2 and 3)
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"Article 1
For the application of this Regulation, the States referred to in the 1st sentence of paragraph 3 of the Protocol of signature of Additional Protocol No. 2 of 17 October 1979 to the revised Convention for the Navigation of Rhine are assimilated to the Contracting States of the said Convention. The term "Contracting State" in the these Regulations always include each of these assimilated States.
[...]
Article 3
1. The document referred to in paragraph 1 of article 2 will only be drawn up for a boat if its owner: 
a) as a natural person has the nationality of one of the Contracting States and his domicile or habitual residence in one of these States; Where
b) as a legal person governed by public law is constituted under the legislation of a Contracting State and has its head office; Where
c) as a legal person or company governed by private law:
aa) is incorporated in a Contracting State in accordance with its laws;
bb) has the seat and center of commercial activity as well as the place from which the operation of the vessel is directed, in that Contracting State, and
cc) is managed and directed by people, the majority of whom are nationals of States Contractors and who have their domicile or habitual residence as well as, in the case of a person moral, their seat in one of these states.
2. However, the establishment of the document for a boat of a legal person or company of private law must be refused, if it is composed in such a way that the persons participating directly or indirectly with the majority of the financial results of the company or having the majority of the shares giving the right to the vote or to the majority of the voting rights, or are not nationals of the States Contracting parties either do not have their domicile, seat or habitual residence in one of these States.
3. In the presence of trust relationships or similar arrangements, the conditions set out above must also be completed by the persons on whose behalf or in whose interests it is processed.
4. A Contracting State may, exceptionally, after consultation with the Central Commission, grant exceptions to the majority required in paragraphs 1, letter c) cc) and 2 above, provided that the objective of Additional Protocol No. 2 to the revised Convention for the Navigation of the Rhine is not compromise. The Central Commission may set the general conditions under which these exemptions will be granted.
Article 4
1. In the case of a boat held in co-ownership, the co-owner (s) who hold the majority of the shares of the co-ownership and who manage the co-ownership must or must meet the conditions referred to in article 3.
2. If among the co-owners concerned there are legal persons or companies governed by private law, the people who manage and direct these companies as well as those who directly or indirectly to the financial results of these must all be nationals of the Contracting States and have their domicile, seat or habitual residence in one of these States.[...]" (Application Regulation for the provisions of paragraph 3 of Article 2 of the revised Convention for Rhine Navigation and numbers 1 and 3 of the Protocol of Signature of Additional Protocol No. 2 to the said Convention of 17 October 1979, Annex to Protocol 3, signed in Strasbourg on 17 October 1979, entry into force on 1 September 1982, Articles 1, 3 and 4  [google translation])
Revised Convention for the Navigation on the Rhine, signed in Mannheim on 17 October 1868, entry into force of the revised version on 14 April 1967, Articles 2, 3 and 4, including amendments brought by Additional Protocol No. 2 of 17 October 1979
Protocol of Signature of Additional Protocol No. 2 to the revised Convention for Rhine Navigation, signed in Strasbourg on 17 October 1979, entry into force on 1 February 1985, Sections 1, 2 and 3
Application Regulation for the provisions of paragraph 3 of Article 2 of the revised Convention for Rhine Navigation and numbers 1 and 3 of the Protocol of Signature of Additional Protocol No. 2 to the said Convention of 17 October 1979, Annex to Protocol 3, signed in Strasbourg on 17 October 1979, entry into force on 1 September 1982, Articles 1, 3 and 4
[<a href="https://www.ccr-zkr.org/files/conventions/convrev_f.pdf">Convention</a>],[<a href="https://www.ccr-zkr.org/files/conventions/ProtAdd2_en.pdf">Protocol</a>],[<a href="https://www.ccr-zkr.org/files/fondjurtextes/Resolution1984-I-3_fr.pdf">Reg</a>]