This International Standard is intended to facilitate the changeover by industry and commerce from traditional yarn numbering systems to the Tex System (see ISO/R 1144). It provides a range of recommended rounded linear densities in the Tex System to replace the yarn numbers in the six main traditional numbering systems referred to in section 6 and covers the great majority of yarns currently produced. The rounded tex values for count systems not covered by section 6 (e.g. Dewsbury count) may be ascertained by applying the principle on which the conversion table is based, viz. by using the relevant conversion factor from ISO/R 1144 to give the exact Tex System equivalents and then choosing a range of rounded numbers which are, as far as possible, not more than 2 % different from the exact equivalents.