“Manual Recurring Billing”
The Manual part refers to the payment method used by the customer. The Recurring Billing part refers to an invoice that will have the same line items each period. So like other Recurring Billing methods the Manual Recurring Billing would automatically create a copy of the bill with the new Invoices own Date and Invoice Number and email the new bill to the customer each period. The period would be either daily, weekly, monthly or annually, with a field so that you can put a number of the period/s (eg bill every 2 months). Also the Manual Recurring Billing should have a number of Billing Cycles to create the bill for or a No Charge After field to end the Recurring Billing on.
Also, and this could apply to all Recurring Billing no mater which payment gateway was used. If a Recurring Billing method is set up when the “number of Billing Cycles” or “No Charge After” has been reached an email should be sent to the administrator notifying them that there will be no more bills created for that Recurring Bill.
The description above makes perfect sense to me, however if it does not to you please ask me some questions and I will gladly provide more info.