Cost Center Hierarchy and Profit Center in SAP 2005B

Hi,

Can anyone explain the uses of cost center hierarchy and Profit center in SAPB1?

When seting up a distribution rule there is some option called the "Direct Debit"

This acording to what I have simulated is the "Direct allocation" of Expenses or Revenue as seen in the Profit Center Report.

Is this something to do with the Direct and Indirect expense or revenue accounting?

If not what is the use of this feature?

Regards,