Artikel 20

1. Declarations under article 18, paragraph 2, and article 19, paragraph 1, shall be made at the time of signature, ratification, acceptance, approval or accession. Declarations made at the time of signature are subject to confirmation upon ratification, acceptance or approval.
2. Declarations and their confirmations shall be in writing and formally notified to the depositary.
3. A declaration takes effect simultaneously with the entry into force of this Convention in respect of the State concerned.
4. Any State that makes a declaration under article 18, paragraph 2, and article 19, paragraph 1, may modify or withdraw it at any time by a formal notification in writing addressed to the depositary. The modification or withdrawal shall take effect 180 days after the date of the receipt of the notification by the depositary. If the depositary receives the notification of the modification or withdrawal before entry into force of this Convention in respect of the State concerned, the modification or withdrawal shall take effect simultaneously with the entry into force of this Convention in respect of that State.