Associate Requisition line types to PO line types

Hello Experts

Where to associate requisition line types to PO line types?

There are some profile options like POR: Services based line type etc...but i cannot see all requisition line types in the profile options

Line types like rate based service line type, fixed price service line type of contingent worker, whe a contractor request requisition is created how does the system pick the PO line type during auto create process?

We are in R12.1.2

Thanks

Dilip