Solution : https://service.sap.com/sap/support/notes/531888 (SAP Service marketplace login required)
Key words : 
postprocessing' execution modes, connected oltp system, source code corrections, backorder processing status, backorder processing, confirmation situation, changed items, 'update finished', terms updated, bop reason
Related Notes : 
       
| 375193 | Backorder processing: Composite SAP note on posting |