The Commission on Symbols, Units, and Nomenclature of the International Union of Pure and Applied Physics directs its efforts toward arriving at some international uniformity of the symbols used for various physical quantities and concepts, the names and definitions of units in which physical quantities are measured and to certain nomenclature questions. Uniformity in the use of symbols, units, and nomenclature is difficult to achieve for many reasons and complete agreement on such matters will probably not be arrived at in the foreseeable future. Some degree of international consistency in the usage of physical terms can, however, be had and Document UIP 6 (1955), reproduced here, is the most recent publication on this matter by the International Union of Pure and Applied Physics in this respect. The Commission hopes to enlarge this work in succeeding years. It will welcome suggestions regarding the present work, which it recognizes as imperfect, and regarding the manner and the scope of the proposed extension of its work. Such suggestions may be sent to the chairman of the Commission, Professor Harald H. Nielsen, Department of Physics and Astronomy, The Ohio State University, Columbus, Ohio.