The United Nations Secretariat, in April 2010, pursuant to Secretary-General’s bulletin ST/SGB/2002/5, promulgated United Nations Staff Selection System administrative instruction (ST/AI 2010/3) dated 22 April 2010. :p2, preamble Administrative instruction ST/AI 2010/3 supersedes and abolishes the administrative instructions titled “Staff selection system” (ST/AI/ 2006/3/Rev.1), “Technical cooperation personnel and OPAS officers" (ST/AI/297 and Add.1), and “Movement of staff from the Field Service category to the Professional category” (ST/AI/360/Rev.1 and Corr.1). he intent of the new system is to integrate "recruitment, placement, promotion and mobility of staff within the Secretariat" up to and including D-1 and equivalent posts. section 2.1 The new system introduces a new requirement of periodic 'mobility' for promotion for "Staff in the Professional and above categories, up to and including those at the D-2 level".