FileIO Adapter

I want to set up the File IO adapter to output a TAB delimitted file in the form of a Purchase Order with multiple items and multiple schedule line tems. Ex:
PO Header
PO Detail
Schedule Line Item1
Schedule Line item2
Schedule Line Item1
Schedule Line Item2
So I use the DLOOperation template to do the tab delmitted.
My question is: How do I specify the repeating portion for the items and schedule line item in the Record Layout area of the adapter?