This document determines the fuel quality classes and specifications of graded wood chips. This document covers only wood chips produced from the following raw materials (see ISO 17225-1:2021, Table 1): 1.1 Forest, plantation and other virgin wood; 1.2 By-products and residues from wood processing industry; 1.3.1 Chemically untreated used wood. This document covers only wood chips, which are produced with sharp tools, and does not cover hog fuel, which is produced with blunt tools.