Solution : https://service.sap.com/sap/support/notes/513895 (SAP Service marketplace login required)
Key words : 
execute backorder processing, spool request, 'result output', bop variant, solution implement, background reason, background, prerequisites
Related Notes : 
       
| 540849 | Results display does not perform well with simulation | 
| 375193 | Backorder processing: Composite SAP note on posting |