68 Final provisions Article 27 1 The present Protocol is open for signature by any State that has signed the Convention. 2 The present Protocol is subject to ratification by any State that has ratified or acceded to the Convention. Instruments of ratification shall be deposited with the Secretary-General of the United Nations. 3 The present Protocol shall be open to accession by any State that has ratified or acceded to the Convention. 4 Accession shall be effected by the deposit of an instrument of accession with the SecretaryGeneral of the United Nations. 5 The Secretary-General of the United Nations shall inform all States that have signed the present Protocol or acceded to it of the deposit of each instrument of ratification or accession. Article 28 1 The present Protocol shall enter into force on the thirtieth day after the date of deposit with the Secretary-General of the United Nations of the twentieth instrument of ratification or accession. 2 For each State ratifying the present Protocol or acceding to it after the deposit with the Secretary-General of the United Nations of the twentieth instrument of ratification or accession, the present Protocol shall enter into force on the thirtieth day after the date of deposit of its own instrument of ratification or accession. Article 29 The provisions of the present Protocol shall extend to all parts of federal States without any limitations or exceptions. Article 30 No reservations shall be made to the present Protocol. Article 31 The provisions of the present Protocol shall not affect the obligations of States Parties under any regional convention instituting a system of visits to places of detention. The Subcommittee on Prevention and the bodies established under such regional conventions are encouraged to consult and cooperate with a view to avoiding duplication and promoting effectively the objectives of the present Protocol. Article 32 The provisions of the present Protocol shall not affect the obligations of States Parties to the four Geneva Conventions of 12 August 1949 and the Additional Protocols thereto of 8 June 1977, nor the opportunity available to any State Party to authorize the International Committee of the Red Cross to visit places of detention in situations not covered by international humanitarian law. Article 33