A/RES/55/255 2. This Protocol shall also be open for signature by regional economic integration organizations provided that at least one member State of such organization has signed this Protocol in accordance with paragraph 1 of this article. 3. This Protocol is subject to ratification, acceptance or approval. Instruments of ratification, acceptance or approval shall be deposited with the Secretary-General of the United Nations. A regional economic integration organization may deposit its instrument of ratification, acceptance or approval if at least one of its member States has done likewise. In that instrument of ratification, acceptance or approval, such organization shall declare the extent of its competence with respect to the matters governed by this Protocol. Such organization shall also inform the depositary of any relevant modification in the extent of its competence. 4. This Protocol is open for accession by any State or any regional economic integration organization of which at least one member State is a Party to this Protocol. Instruments of accession shall be deposited with the Secretary-General of the United Nations. At the time of its accession, a regional economic integration organization shall declare the extent of its competence with respect to matters governed by this Protocol. Such organization shall also inform the depositary of any relevant modification in the extent of its competence. Article 18 Entry into force 1. This Protocol shall enter into force on the ninetieth day after the date of deposit of the fortieth instrument of ratification, acceptance, approval or accession, except that it shall not enter into force before the entry into force of the Convention. For the purpose of this paragraph, any instrument deposited by a regional economic integration organization shall not be counted as additional to those deposited by member States of such organization. 2. For each State or regional economic integration organization ratifying, accepting, approving or acceding to this Protocol after the deposit of the fortieth instrument of such action, this Protocol shall enter into force on the thirtieth day after the date of deposit by such State or organization of the relevant instrument or on the date this Protocol enters into force pursuant to paragraph 1 of this article, whichever is the later. Article 19 Amendment 1. After the expiry of five years from the entry into force of this Protocol, a State Party to the Protocol may propose an amendment and file it with the SecretaryGeneral of the United Nations, who shall thereupon communicate the proposed amendment to the States Parties and to the Conference of the Parties to the Convention for the purpose of considering and deciding on the proposal. The States Parties to this Protocol meeting at the Conference of the Parties shall make every effort to achieve consensus on each amendment. If all efforts at consensus have been exhausted and no agreement has been reached, the amendment shall, as a last resort, require for its adoption a two-thirds majority vote of the States Parties to this Protocol present and voting at the meeting of the Conference of the Parties. 2. Regional economic integration organizations, in matters within their competence, shall exercise their right to vote under this article with a number of 10