The activities constituting “production” within the meaning of the phrase “engaged in * * * the production of goods for commerce” are defined in section 3(j) of the Act. (The statutory definition is set forth in § 779.13.) The handling or otherwise working on goods intended for shipment out of the State, directly or indirectly, in engagement in the “production” of goods for commerce. Thus, employees in retail stores who sell, pack, or otherwise work on goods which are to be shipped or delivered outside of the State are engaged in the production of goods for commerce. Typically, but not exclusively, employees engaged in the production of goods for interstate or foreign commerce, include those who work in manufacturing, processing and distributing establishments, including wholesale or retail establishments, that produce goods for interstate or foreign commerce. This includes everyone, including office, management, sales and shipping personnel, and maintenance, custodial and protective employees, whether they are employed by the producer or an intermediary. Employees may be covered even if their employer does not ship his goods directly in such commerce. The goods may leave the State through another firm. The workers may produce goods which become a part or ingredient of goods shipped in interstate or foreign commerce by another firm. Also covered are workers who are engaged in a closely related process or occupation directly essential to such production. (See § 779.105.)