22 contained in Annex 1 to this Protocol and in conformity with the adopted tariff modalities. The Schedules of Tariff Concessions, the adopted tariff modalities and outstanding work on tariff modalities to be negotiated and adopted, shall be an integral part of this Protocol. 2. Notwithstanding the provisions of this Protocol, State Parties that are members of other RECs, which have attained among themselves higher levels of elimination of customs duties and trade barriers than those provided for in this Protocol, shall maintain, and where possible improve upon, those higher levels of trade liberalisation among themselves. Article 9 General Elimination of Quantitative Restrictions The State Parties shall not impose quantitative restrictions on imports from or exports to other State Parties except as otherwise provided for in this Protocol, its Annexes and Article XI of GATT 1994 and other relevant WTO Agreements. Article 10 Export Duties 1. State Parties may regulate export duties or charges having equivalent effect on goods originating from their territories. 2. Any export duties or taxes, imposed on or in connection with, the exportation of goods, applied pursuant to this Article shall be applied to goods exported to all destinations on a non-discriminatory basis. 3. A State Party that introduces export duties or taxes on, or in connection with, the exportation of goods in accordance with paragraph 2 of this Article, shall notify the Secretariat ninety (90) days from the introduction of the said export duties or taxes. Article 11 Modification of Schedules of Tariff Concessions 1. In exceptional circumstances, a State Party may request for modification of its Schedules of Tariff Concessions. 2. In such exceptional circumstances, a State Party (hereinafter referred to as the “modifying State Party”) shall submit to the Secretariat, a written request, together with evidence of the exceptional circumstances for such a request.