These regulations are intended to provide off-street spaces for the parking of the automobiles of tenants of the premises and visitors in the case of residential uses, and for clients, customers, employees and callers in the case of nonresidential uses. They are required to be kept accessible for these purposes continuously, and the use of any such required space or spaces, or of any driveway or maneuvering space necessary to provide access thereto for the storage of a trailer coach, boat, vehicle trailer, unmounted camper unit, or goods of any kind shall constitute discontinuance thereof in violation of Section 17.52.760. (Prior gen. code § 8-63.2)