Solution : https://service.sap.com/sap/support/notes/959698 (SAP Service marketplace login required)
Key words : 
sap ambiguous blended code page configurations mdmp systems, twin upgrade & unicode conversion guide, ambiguous blended code page, single code page systems, code page configuration types, additional information general information, twin upgrade & unicode conversion, standard unicode conversion approach, combined upgrade & unicode conversion, pure mdmp configurations
Related Notes : 
       
| 1322715 | Unicode FAQs | 
| 1319517 | Unicode Collection Note | 
| 928729 | Combined Upgrade & Unicode Conversion (CU&UC) | 
| 79991 | Multi-Language and Unicode support of SAP applications | 
| 73606 | Supported Languages and Code Pages |