Permits for Low-Traffic Zones (LTZ) aim to reduce / limit traffic, rather than to change the emissions standard of the vehicles used in the area like an LEZ does. Certain categories of vehicles or trips, for example those living in the area, are permitted to enter. They are given a permit to prove their eligibility. In addition to permits, there are usually exempted vehicles; these are usually vehicles readily identified by their livery / visual characteristics that are needed for the functioning of the town, e.g. emergency vehicles, public transport, postal vehicles etc. (see also Exemptions for Low-Traffic Zones)