Help needed in Idoc To File Scenario

Question

Hi Experts,
My scenario is Idoc to File.
Here my job is to convert the purchase order idoc into xml file.
In this there are three conditions.
                   converting the standard PO into xml file
(ii)                 converting the PO with serial number  into xml file
(iii)                converting the PO using serial number with subcontracting into xml file
so what I feel is I need to create one scenario and based on the condition that particular PO will convert into xml file.
Conditions:
                   if no condition is specified then it is standard PO first case
(ii)                 if field tdline ne space then it is PO with serial number second case
(iii)                if field pstyp eq 3 then it is PO using serial number with    subcontracting third case.
Please guide how to do this scenario.
IR:
1)       how many data types I need to create
2)       how many message types I need to create
3)       how many message interfaces I need to create
4)       how many message mappings I need to create
5)       how many message interfaces I need to create
ID:
1)       how many receiver determinations I need to create
2)       how many interface determinations I need create
3)       how many receiver agreements I need to create
And where to write the conditions at message mapping level or at receiver determination level.
Kindly provide solution to every point.
Regards,
Venkat.

Answer 1

1) if no condition is specified then it is standard PO first case
2) if field tdline ne space then it is PO with serial number second case
3) if field pstyp eq 3 then it is PO using serial number with subcontracting third case.
you have to create
1. outbound ( IDOC)
2. 3 Inbound (same MT)
create 3 mapping program each for 1 condition
create 3 interface mappings
ID:
1 reveri BS.
3 Interface determinations, so 3 receiver agrement.......
you can put the condition on the mapping or in the condition tab of the interface determinations.