In case of a written protest against any proposed amendment of the regulations or districts, signed and acknowledged by the owners of 20% of the frontage proposed to be altered, or by the owner of 20% of the frontage immediately adjoining or across an alley therefrom, or by the owners of 20% of the frontage directly opposite the frontage proposed to be altered, is filed with the City Clerk, the amendment shall not be passed except by a favorable vote of two-thirds of the members of the City Council.
(Prior Code, § 156.343)