Over the years, the UN has developed an extensive treaty-registration system, detailed in its Repertory of Practice and Treaty Handbook.[31] From December 1946 through July 2013, the United Nations Secretariat recorded over 200,000 treaties published in the United Nations Treaty Series pursuant to Article 102 of the UN Charter.[32] Still, today "a substantial number of treaties are not registered, mainly due to practical reasons, such as the administrative or ephemeral charter of some treaties."[33] Non-registered treaties are not necessarily secret, since such treaties are often published elsewhere.[31]