Article 17 Vienna Convention on the Law of Treaties

Consent to be bound by part of a treaty and choice of differing provision

1. Without prejudice to articles 19 to 23, the consent of a State to be bound by part of a treaty is effective only if the treaty so permits or the other contracting States so agree.

2. The consent of a State to be bound by a treaty which permits a choice between differing provisions is effective only if it is made clear to which of the provisions the consent relates.

See also: Article 16 Vienna Convention on the Law of Treaties