SAP SD - NEED LOGIC TO MAP INVOIC01 IDOC TO EDI 810

Hi,

I am new to SAP,Just started learning SAP IDOC.I am trying to map INVOIC01 IDOC to EDI 810 ANSI X12 format.

I have exported the INVOIC01 structure through TCODE WE60. But looking at the structure I am not sure from where we get the

below values on an INVOIC01 IDOC to map to an EDI 810.

* Carrier details

* Invoice payment terms & Deffered due dates and amount

* Discounts, Allowances, Charges

* Basis of unit of measure

To clarify my question on what exactly I am expecting,I will give you a sample mapping for currency.

Could anyone of you please let me know where on INVOIC01 IDOC we get these values?

Thanks

Jyothi