This U.S. industry comprises establishments primarily engaged in printing special forms, including checkbooks, for use in the operation of a business. The forms may be in single and multiple sets, including carbonized, interleaved with carbon, or otherwise processed for multiple reproduction. Cross-References. Establishments primarily engaged in manufacturing single layered continuous computer paper and similar products are classified in U.S. Industry 322231, Die-Cut Paper and Paperboard Office Supplies Manufacturing.