The FTC defined operating income as total revenues (including transfers from other units) less cost of goods sold, less selling, advertising, and general and administrative expenses. Both expenses and assets were further divided into 'traceable' and 'untraceable' components, the traceable component being directly attributable to the line of business and the untraceable component being allocated by the reporting firm among lines of business using 'reasonable procedures.' In 1975, 15.8 percent of the total expenses and 13.6 percent of total assets of the average business-unit were allocated