- for the purpose of Test Method D4749, the sieve designating the upper limit or topsize shall be that sieve of the series given in the Standard Series of Sieves section with the smallest openings upon which is cumulatively retained a total of less than 5 % of the sample. This defined topsize is not to be confused with the size of the largest particle in the lot. D4749
ASTM D121-09a Standard Terminology of Coal and Coke. 2014.