On 11 December 1989, over the Zone of Cooperation, the Treaty between Australia and the Republic of Indonesia on the Zone of Cooperation in an Area between the Indonesian Province of East Timor and Northern Australia was signed. The closing formula: done over the Zone of Cooperation; two originals in the English language. Signatories, in Australian Treaty Series 1991 No. 9: Gareth Evans, Minister for Foreign Affairs and Trade, and Ali Alatas, Minister for Foreign Affairs. The ATS note: the Treaty was concluded aboard an aircraft flying above the Timor Sea in an area designated as the Zone of Cooperation. Registration: UNTS I-28462, volume 1654.

The preamble: the United Nations Convention on the Law of the Sea done at Montego Bay and, in particular, Article 83 — provisional arrangements of a practical nature which do not jeopardize or hamper a final continental-shelf delimitation. The purpose: to enable exploration for and exploitation of the petroleum resources of the continental shelf of the area yet to be the subject of permanent delimitation, without affecting existing shelf-delimitation agreements between the two countries.

Article 2(1): a Zone of Cooperation comprising Areas A, B and C. Article 2(2): in Area A, joint control and equal sharing of the benefits; in Area B, Australia shall notify and share Resource Rent Tax; in Area C, Indonesia shall notify and share Contractors' Income Tax. Article 4(1)(b): ten per cent of gross Resource Rent Tax collected from Area B. Article 4(2)(b): ten per cent of Contractors' Income Tax from Area C. Article 2(3): nothing in this Treaty and no acts or activities while it is in force shall prejudice either Contracting State's position on a permanent continental-shelf delimitation, nor affect the respective sovereign rights claimed. Article 2(4): the Contracting States shall continue their efforts to reach a permanent delimitation.

Article 3: in Area A, rights and responsibilities shall be exercised by the Ministerial Council and the Joint Authority; petroleum operations through production-sharing contracts with limited-liability corporations established for the sole purpose of the contract. Article 5: the Council, an equal number of Ministers, annual meetings alternating between the two States, decisions by consensus. Article 7: the Joint Authority shall have juridical personality; its head office in Indonesia and an office in Australia, each headed by an Executive Director; decisions of the Executive Directors by consensus, failing which the matter is referred to the Council.

Article 32: this Treaty shall enter into force thirty days after the Contracting States have notified each other in writing that their respective requirements have been complied with. Notes were exchanged at Canberra on 10 January 1991. Entry into force: 9 February 1991. Article 33: an initial term of forty years, then successive terms of twenty years unless a permanent continental-shelf delimitation has been concluded. Article 30: disputes between the Contracting States shall be resolved by consultation or negotiation. The Timor Sea Treaty of 20 May 2002 is a later instrument, not this text.

The Timor Sea, the area over which the Treaty was signed, not a signing room. MODIS satellite image. Wikimedia Commons, public domain.

For context: Timor Gap Treaty. The text: UNTS volume 1654, No. 28462, Treaty on the zone of cooperation in an area between the Indonesian province of East Timor and Northern Australia.