A method of computing the basis weights of all
grades of paper on a sheet size of 25 by 40 inches
(1,000 square inches) and a 1,000 sheet count,
i.e., the 1,000, 1,000 or m.m. system. The
traditional writing paper basis weight of 20
pounds (17 X 22�) becomes 107 pounds on an
m.m. basis (25 X 40�), while regular
60-pound book paper (25 X 38�) becomes 126
pounds, and so on. The m.m. system, which
originated in the 1920s, is not in general use but
printers, paper buyers, as well as others, often
find it advantageous to use. In applying the m.m.
system, a conversion chart is used which lists
various grades with their traditional basis
weights and corresponding m.m. factors. (17 , 320 , 329 )