The concept of Natural Heritage is defined under Article 2 of the Convention and further elaborated in the World Heritage Operational Guidelines (paragraph 77), which also contain the specific criteria and conditions of integrity for assessing Outstanding Universal Value(s) of prospective World Natural Heritage properties. The UNESCO World Heritage Centre's Natural Heritage Strategy, endorsed by the World Heritage Committee, outlines the guiding principles, mission statement, strategic orientations, and working methods of all activities relating to Natural Heritage. The two major thematic Natural Heritage Programmes are the World Heritage Marine Programme and the Forests Programme. Other major Natural Heritage initiatives include the Tourism Programme and the Rapid Response Facility.