States A, B, C, D and E signed a treaty which provided for free movement of all agricultural products grown/produce in any of the contracting party (The Treaty). This means that States A, B, C, D and E agree that no customs duties and charges equivalent to customs duties (CEEs), such as inspection fees, will be imposed on agricultural products imported from the territory of any contracting party. The Treaty allows a contracting party to carry out free inspections of agricultural goods if there is evidence that a product in question constitutes a danger or a potential danger to health or life of humans, animals or plants. The Treaty was subject to ratification by each of State A, B, C, D, and E.

State B is known worldwide for the quality and style of leather shoes made in that State. Manufacturers of shoes in State B put pressure on the government of State B to include the following statement at the time of ratification of the Treaty:

"State B understands that products made of animal leather should not be regarded as agricultural products. If this understanding of State B is not accepted by the contracting parties, State B will no longer wish to be a contracting party to the Treaty".

State D ratified the Treaty, but made an objection to the statements made by States A, B and C, whilst allowing the Treaty to enter into force between itself and States A, B and C.

What is the relationship under the treaty between State B and State D??