“Industry” means any business, trade, undertaking, manufacture or calling of employers and includes any calling, service, employment, handicraft, or industrial occupation or avocation of workmen;
“Industrial establishment or undertaking” means an establishment or undertaking in which any industry is carried on:
Provided that where several activities are carried on in an establishment or undertaking and only one or some of such activities is or are an industry or industries, then,—
(a) if any unit of such establishment or undertaking carrying on any activity, being an
industry, is severable from the other unit or units of such establishment or undertaking, such unit shall be deemed to be a separate industrial establishment or undertaking;
(b) if the predominant activity or each of the predominant activities carried on in such
establishment or undertaking or any unit thereof is an industry and the other activity or each of the other activities carried on in such establishment or undertaking or unit thereof is not severable from and is, for the purpose of carrying on, or aiding the carrying on of, such predominant activity or activities, the entire establishment or undertaking or, as the case may be, unit thereof shall be deemed to be an industrial establishment or undertaking;]
