Revision Standard - Superseded. This standard describes the International System of Units (SI), the modern version of the metric system. It includes listings of the base units, supplementary units, and units derived therefrom. Guidance is provided on application of the SI prefixes, other units in use with SI (including units accepted for limited use and units to be abandoned), and unit selection. A section on style and usage covers the writing of unit symbols and names, pronunciation, and recommendations for numbers. Extensive guidance is provided on conversion and rounding along with a very extensive table of conversion factors. An appendix provides background information in the development of SI.