For purposes of Commission rulemaking in accordance with the provisions of Chapter Six of the Administrative Procedure Act (5 U.S.C. 601 et seq.), and unless otherwise defined for purposes of a particular rulemaking proceeding, the terms “small business” and “small organization,” for purposes of the Public Utility Holding Company Act of 1935, shall mean a holding company system whose gross consolidated revenues from sales of electric energy or of natural or manufactured gas distributed at retail for its previous fiscal year did not exceed $1,000,000. There may be excluded from such gross revenues:

(a) Sales or electric energy or natural or manufactured gas to tenants or employees of any operating subsidiary company of such holding company for their own use and not for resale; and

(b) Sales of gas to industrial consumers or in enclosed portable containers.