It is used as propellant for some metered dose inhalers. One major point of differentiation between rolling techniques is between Metered and Unmetered rolls. Philadelphia, encourages parking space turnover by charging escalating parking fees when metered time is added. All taxis are metered, which doesn't necessarily mean the meter will be used. The borough offers 6-month parking permits that can be used in certain metered spots. Street parking downtown is metered except on holidays. Johannesburg has two kinds of taxis, metered taxis and minibus taxis. Taxis are metered and are generally more expensive than auto-rickshaws. This can potentially distribute updates faster while reducing usage for networks with a metered connection. Some are metered to provide uniform usage. They are metered and subject to a 15-percent surcharge. The taxis are metered and most accept credit cards. A gas holder provided storage for the purified, metered gas. Since most connections are not metered, it is difficult to charge tariffs depending on consumption. Water for residential properties is not metered in Scotland.