Solution : https://service.sap.com/sap/support/notes/553110 (SAP Service marketplace login required)
Key words : 
smod/cmod - type user exits, complete customer user exit coding, smod/cmod user exits, related include file z_rsunuxi1, existing sap user exits, critical user exit coding, /3 enterprise user exit reason, change unicode-flag immediately, -critical user exits, user exit coding
Related Notes : 
       
| 1319517 | Unicode Collection Note | 
| 1108861 | Add. info. on upgrading to SAP CRM 5.0 SR3 ABAP | 
| 1108700 | Add. info. on upgrading to SAP SCM 5.0 SR3 ABAP | 
| 1071404 | Add. info.: Upgrade to SAP CRM 2007 ABAP | 
| 1039395 | Add. info.: Upgrade to SAP CRM 5.2 ABAP | 
| 1010762 | Add. info. on upgrading to SAP SCM 5.1 ABAP | 
| 975861 | Add. Info.: Upgrade to SAP SRM Server 6.0 ABAP | 
| 961512 | Add. info. on upgrading to SAP SCM 5.0 SR2 ABAP | 
| 961511 | Add. info.: Upgrade to SAP CRM 5.0 SR2 ABAP | 
| 947991 | Add. info.: Upgrade to SAP CRM 5.1 ABAP | 
| 925240 | Add. Info. on upgrading to SAP SCM 5.0 SR1 ABAP | 
| 913849 | Add. info.: Upgrade to SAP CRM 5.0 ABAP SR1 | 
| 826488 | Enhancements to upgrade on SAP CRM 5.0 ABAP | 
| 826093 | Add. info. on upgrading to SAP SCM 5.0 ABAP | 
| 737800 | Enhancements to upgrade on SAP CRM 4.0 SR1 | 
| 737696 | Add. info on upgrade to SAP R/3 Enterprise 4.70 Ext. 2 SR1 | 
| 637683 | Add info about upgrade to SAP R/3 Enterprise Core 4.70 Ext 2 | 
| 628205 | User Includes:Behavior within non-Unicode SAP R/3 Enterprise | 
| 620301 | User exit scanners should also recognize SCM 4.0 | 
| 603852 | Additional information about upgrading to SAP SCM 4.0 | 
| 587896 | Add. info on upgrade to SAP R/3 Enterprise Core 4.70 SR1 | 
| 540911 | Unicode restrictions for R/3 Enterprise, ECC 5.0, ECC 6.0 | 
| 513536 | Add. information on upgrade to SAP R/3 Enterprise Core 4.70 | 
| 493387 | Potential effects of table- and structure - extensions |