In the course of organizing his staff, the DDR&E appointed Assistant Directors for several types of warfare systems. Following this action in late 1959, the Board made a study of the structure of scientific and engineering advisory bodies. Its report on this study was implemented by DoD Directive 5129.22, "Defense Science Board Charter," dated April 10, 1961. This directive was revised and reissued on February 17, 1971. In 1978, the title, Director of Defense Research and Engineering, was changed to Under Secretary of Defense for Research and Engineering (USDRE). On July 1, 1986, the title, the Undersecretary of Defense for Research and Engineering, was changed to Under Secretary of Defense for Acquisition (USD/A). On January 1, 1990, the Defense Manufacturing Board, which had reported directly to the USD(A), merged into the Defense Science Board, adding manufacturing issues to the list of items of interest.