Solution : https://service.sap.com/sap/support/notes/1563486 (SAP Service marketplace login required)
Key words : 
symptom question library mass upload, prerequisites functionality clarification solution, question library upload, terms question library, file format reason, xml upload, attached document
Related Notes : 
       
| 1562839 | Question Library: XML upload | 
| 1549787 | Process Control 10.0 Support Package 03 - Master Note |