This strategy features in the framework of Agenda 21 as formulated at UNCED (Rio de Janeiro, 1992), now coordinated by the United Nations Commission on Sustainable Development and implemented through national and local authorities. Agenda 21 recommends that all countries should undertake during the period 1993-2000, with the active participation of the business sector as appropriate, pilot projects in selected cities for the collection, analysis and subsequent dissemination of urban data including environmental impact analysis, at the local, state/provincial, national and international levels and the establishment of city data management capabilities. Agenda 21 also recommends that United Nations organizations such as Habitat, UNEP and UNDP could provide technical advice and model data management systems.