This classification for ordering, handling, and accounting for all material and supplies should be put in use on all railroads under Federal control at or before the taking of the next material inventory.

Construction material should be included with the same kind of material for maintenance or operation.

If further detail of any class is required, further subdivisions may be made.

If less detailed classification is desired, subclasses and classes may be consolidated, provided, however, that the principle of the classification must be maintained and none of the four general classes consolidated.