When using classifications both in the Main Level and in the Line Level, what is the typical use cases of the Main Level (where its value will be different from the Line Level)? Say a vendor bill, for the line level which normally includes expenses, it will most likely be associated to the department/s that 'need/s' such expenses. For the Main Line (which is for AP and only one value may be entered), is it just for the AP department (or its equivalent) or are there any other use case for this that makes sense? Thanks!