For the final step (If you were able to scan/ocr/analyze/verify the documents with multiple formats, don't forget to deposit a patent 
)
Some tools :
- BAPI as BAPI_ACC_DOCUMENT_POST (or BAPI_INCOMINGINVOICE_PARK for MM related invoice)
- IDOC INVOIC and associated FM as IDOC_INPUT_INVOIC_FI (or IDOC_INPUT_INVOIC_MM for MM related invoice)
Regards,
Raymond