Reserves and resources
Solid fuels. Coal - Economics and Resources

The most international classification was devised by the United Nations Economic Commission for Europe (UNECE) with contributions from the Council of Mining and Metallurgical Institutions (CMMI) in 1998. Each coal deposit or part of a coal deposit is assessed from three angles:

• the precision of geological reconnaissance, mainly the spacing of exploration drill holes;

• progress of the development project, mainly the accuracy of studies and economic assessments;

• the project's economic viability under current economic conditions.