This document sets forth standard metric practice for the United States. Modern metric practice is based on the International System of Units, a system developed and maintained by the General Conference on Weights and Measures (abbreviated as CGPM from the official French name, Conference GnCrale des Poids et Mesures) and intended as a basis for worldwide standardization of measurement units. The name International System of Units and the international abbreviation SI (from the French name, Le Syst6me International dunites) were adopted by the 11 th CGPM in 1960. SI is a complete, coherent system that is being universally adopted. Information is included on SI, a limited list of non-SI units recognized for use with SI units, and a list of conversion factors from non-SI to SI units, together with general guidance on proper style and usage. An understanding of SI and careful use according to this standard will help to avoid the degradation that has occurred in some previous measurement systems.