Exemption for canteen food services in air-conditioned factory premises extends to outsourced caterers serving employees. Services of serving food or beverages in a factory-maintained canteen are exempt where the factory premises include air-conditioning or central air-heating at any time during the year; the exemption covers services provided in relation to serving food in such air-conditioned factory canteens and extends to external caterers who bring and serve food within the factory's air-conditioned restaurant.