Periodic service properties window consists of two pages:
If the number of charge-offs per week is not set in the accounting period properties, the period is divided into equal parts anyway, but the number of parts is given by the flow_discounts_per_period system parameter (by default 64). At the end of each part the event handler runs through all periodic services linked to this period and having flow method of charging. For every such service, the amount to be charged is determined, and if it exceeds the discount_barrier parameter, the charge-off is made.
All these parameters are also relevant for services of other types, which however possess a number of extra parameters specific to each type.
Parameters of the corresponding service link are described in Periodic service link.