The Asia-Pacific Trade Agreement (APTA), previously known as the Bangkok Agreement and renamed 2 November 2005, was signed in 1975. It is the oldest preferential trade agreement between countries in the Asia-Pacific region. Its aim is to promote economic development and cooperation through the adoption of mutually beneficial trade liberalization measures. APTA is open to all members of the United Nations Economic and Social Commission for Asia and the Pacific, which serves as the APTA Secretariat. Members of APTA are currently participating in the Fourth Round of Tariff Concessions, which are expected to conclude in October 2009.