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Owing to contributions of its members, H-A-O developed into an association of Hanoi-Amsterdam HS' current students, alumni, as well as students from other schools. On November 23, 2004, Hanoi - Amsterdam Organization was registered as non-profit corporation under the Educational Services category. It has more than 19,000 members (as of October 2007) and more than 1,800,000 posts on its discussion boards.