Chapter XV of the United Nations Charter deals with the UN Secretariat. It designates the UN secretary-general as the chief administrative officer of the organization, which includes the staff of ECOSOC, the Trusteeship Council, and other organs. Chapter XV is analogous to Article 6 of the Covenant of the League of Nations.
The secretary-general of the United Nations (UNSG or UNSECGEN) is the chief administrative officer of the United Nations and head of the United Nations Secretariat, one of the six principal organs of the United Nations.
The role of the secretary-general and of the secretariat is laid out by Chapter XV (Articles 97 to 101) of the United Nations Charter. However, the office's qualifications, selection process and tenure are open to interpretation; they have been established by custom.