1.1 This practice covers a system of general classification for the basic rubbers both in dry and latex forms determined from the chemical composition of the polymer chain. 1.2 The purpose of this practice is to provide This practice covers a system of general classification or nomenclature for rubber and rubber latices. Rubbers in both dry and latex form shall be coded from the chemical composition of the polymer chain using the following classes: M, N, O, R, Q, T, U