Commodity indexes.

The commodity classification structure of the PPI organizes products by similarity of end use or material composition, disregarding industry of origin. Fifteen major commodity groupings (two-digit commodity codes) make up the All Commodities Index. Each major commodity grouping includes (in descending

order of aggregation) subgroups (three-digit codes), product classes (four-digit codes), subproduct classes (six-digit codes), and individual items (eight-digit codes). Nearly all eight-digit commodities under the traditional commodity coding system are now derived from corresponding industry-classified product indexes. In such instances, movements in the traditional commodity price indexes and corresponding percent changes will be virtually identical to their industry-based counterparts, even if their index levels differ.