Article 12 Vienna Convention on the Law of Treaties

Consent to be bound by a treaty expressed by signature

The consent of a State to be bound by a treaty is expressed by the signature of its representative when:

(a) the treaty provides that signature shall have that effect;

(b) it is otherwise established that the negotiating States were agreed that signature should have that effect; or

(c) the intention of the State to give that effect to the signature appears from the full powers of its representative or was expressed during the negotiation.

2. For the purposes of paragraph 1:

(a) the initialling of a text constitutes a signature of the treaty when it is established that the negotiating States so agreed;

(b) the signature ad referendum of a treaty by a representative, if confirmed by his State, constitutes a full signature of the treaty.

See also: Article 11 Vienna Convention on the Law of Treaties