In 1990 the ITTC proposed that by 2000 all exports of tropical timber would come from sustainably managed sources, and this goal was adopted.[4] In 1987 the ITTO commissioned the Harvard Institute for International Development to prepare a review of current knowledge of multiple-use management of tropical forests. Of interest was the potential for non-timber forest products and services that could assist in sustaining the forests. HIID completed the study in 1988 and issued updated versions in 1990 and 1992.[5]