Hello Charles,
In FICA, it depends upon what type of invoicing you are processing. In utility industry generally IS-U invoicing processing is carried out whereas mostly in public sector, convergent invoicing is processed.
Each of the processing types have different tables. So please clarify that.
Also, with PO are you talking about purchase order ? If that is the case, I would assume that you would leverage the sales order and hence SD billing functionality to integrate with FICA. Please confirm this.
Accordingly I can take you through the FICA tables.
Thanks,
Bodhisattwa