Solution : https://service.sap.com/sap/support/notes/517583 (SAP Service marketplace login required)
Key words : 
/sapapo/bop_resmod user parameter, default values' view, v_tvta_vfp-revfp reason, initial data transfer, /sapapo/bop, transferring results, availability check, correctly analyzed, backorder processing, 'sales area
Related Notes : 
       
| 517582 | |
| 375193 | Backorder processing: Composite SAP note on posting |