Solution : https://service.sap.com/sap/support/notes/337518 (SAP Service marketplace login required)
Key words : 
additional key words transaction, prerequisites solution correct, backorder processing, /sapapo/bop_result, /sapapo/bop, /sapapo/bop_update, source code, classification, confirmation
Related Notes : 
       
| 375719 | Backorder processing: SAPSQL_ARRAY_INSERT_DUPREC | 
| 375193 | Backorder processing: Composite SAP note on posting |