The assessment of global resources of oil and gas will be improved with the implementation of a Bridging Document that relates the reserves and resources in the Oil and Combustible Gas of the Russian Federation Classification (RF2013) to the categories and classes of the United Nations Framework Classification for Resources (UNFC)1 allowing direct comparison to the SPE Petroleum Resources Management System (SPE-PRMS)2. The RF2013 classification of petroleum came into effect in 2016. It establishes the principles for assessment and accounting of reserves and resources of oil, gas and gas condensate in the Russia Federation. UNFC provides a standard tool for managing energy and mineral resources, and is founded on similar principles to the SPE-PRMS, using the SPE-PRMS as the basis for its petroleum commodity specifications. Applicable to all extractive activities, including solid minerals, oil, gas and uranium, as well as injection projects for the geological storage of c02 and renewable energy projects, including geothermal energy, the UNFC ensures that resources are developed transparently, efficiently and sustainably in a socially acceptable manner. A multidisciplinary team consisting of the Expert Group on Resources Classification (EGRC) of the United Nations Economic Commission for Europe (UNECE), the Russian Federation State Committee on Mineral Reserves (GKZ) and representatives of the SPE Oil and Gas Reserves Committee (OGRC) worked in cooperation to develop a mapping between the SPE-PRMS and Russia systems through the UNFC that allows comparison and understanding of the value of development projects. Instructions and guidelines on how to classify estimates of the Russian system using the numerical codes of UNFC were also developed.