Charges incurred for a ProductOffering can take many different forms, such as<br/>        • Recurring Charge – A recurring charge is levied repeatedly. It has a period, such as monthly, quarterly, or yearly. An example would be a monthly charge for long distance. A recurring charge may also limit the application duration. For example, a recurring charge applied only during 6 months for an expensive device.<br/>        • One Time Charge – A one-time charge is levied once. An example is the cost of a cell phone handset or installation fee (FeeProdOfferingPrice valuing an AllowedProductAction).<br/>        • Usage – A charge levied for usage (ProductUsageSpec), based on measuring events. This model distinguishes between simple usage and usage where the charge is described by a tariff.<br/>             • Simple Usage – Simple usage describes a rate where the charge is the same for all events. A 10 cents a minute for long distance plan is one example. <br/>             • Tariff Usage – Tariff usage describes a rate where there are different charges for different types of events. This could include plans, which have different prices for evening minutes and anytime minutes. This usage aggregates a number of simple usages.<br/>