Solution : https://service.sap.com/sap/support/notes/486726 (SAP Service marketplace login required)
Key words :
enter invoice lines, purchase order reference, direct material posting, account posting reason, bapi structure 'headerdata', bapi bapi_incominginvoice_create, bapi bapi_incominginvoice_park, business transactions, posted directly, supply data
Related Notes :
| 516198 | BAPI: Mandatory field "Tax code" in GLACCOUNTDATA |
| 453646 | BAPIs: No direct posting to G/L account/material |