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.

In State C, its citizens, who love milk, and have always taken great care of their health, put pressure on the government to include, at the time of ratification of the Treaty, the following statement:

"All milk coming from any contracting party will be subjected to mandatory inspections which will be free of charge. However, the producers of milk will have to store milk during any inspection in the facilities provided by the government. The government will charge storage fees of $ US 10 per 1000 hectolitres of milk per day".

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 between C and D?