Preventive order to stop obstruction or riot prohibits placing debris on public roads and forbids processions likely to cause affray. A magistrate may direct a person in possession or management of land not to place earth, stones or other dug-up material on an adjoining public road if such deposition risks obstructing users, or may prohibit a procession or assembly of identified persons that is likely to lead to a riot or affray; the order must describe the property or class of persons and be dated, sealed and signed by the court under the prescribed form.