Solution : https://service.sap.com/sap/support/notes/138789 (SAP Service marketplace login required)
Key words : 
field/structure reference type  proposal, production orderbom usagepriority usage svwvo, indicator 'priority bom usage svwvo', additional key words phantom assembly, selid      selpr   bom usg, ecapid             tc04-capid                           pi01 2, parameter passing ecapid = 'pp01', usage 1application pi01, import parameter ecapid, import parameter   ref
Related Notes : 
       
| 134488 | BOM explosion with different usages | 
| 86748 | Material component allocation w. phantom assembly |