clean clean up compulsory green litter man mandatory Mandatory sign no litter no trash no waste roadsign roadsigns sign signs trash trash can UP waste animals prohibited appropriate behavior appropriate behaviour bicycles prohibited black black and white communicating communication denial denied dog informing littering prohibited no animals no bicycles no littering not allowed not permitted permission denied prohibited prohibition prohibitions rules warning white box dump dumping flying garbage graphic icon no notebook notes paper papers rubbish sheets stationery