Solution : https://service.sap.com/sap/support/notes/401255 (SAP Service marketplace login required)
Key words : 
additional key words bop publication, prerequisites missing interface, functions solution delivery, functions require, backorder processing, configuration characteristics, sales orders, data transfer, external interfaces, support package
Related Notes : 
       
| 442259 | Backorder processing: Configuration characteristics | 
| 400662 | Backorder processing: Configuration characteristics | 
| 398486 | Backorder processing: Configuration characteristics | 
| 375193 | Backorder processing: Composite SAP note on posting |