Provides lists of the agreed international symbols and names for the coherent units of the International System of Units known as SI. The tables in the various sections show the one and only SI unit for each of about 500 physical quantities. Physical quantities are defined or identified with varying degrees of completeness. Symbols are recommended for each physical quantity with suggested alternatives in many cases. Recommendations are given for the printing of letters and numbers and of symbols for mathematical operations. A guide is given for the use of the terms coefficient, factor, parameter, number, ratio and constant. Adopted with national modifications from ISO Standards Handbook 2:1982 and ISO 1000-1981.