Solution : https://service.sap.com/sap/support/notes/409792 (SAP Service marketplace login required)
Key words : 
additional key words transaction, parameters process tab, source codethe note 409801, backorder processing results, /sapapo/bop_resultbackorder processing, checked order items, backorder processing, order items, /sapapo/bop, order network
Related Notes : 
       
| 412962 | Backorder processing: Update status not set | 
| 409801 | Backorder processing: item (confirm. cancelled), no update | 
| 388894 | Backorder processing with manufacturing | 
| 375193 | Backorder processing: Composite SAP note on posting |