Solution : https://service.sap.com/sap/support/notes/305570 (SAP Service marketplace login required)
Key words : 
6c sr1 sr2 windows nt windows 2000 r3upr3setup unix as400 reason, referiiing toascii thai codepage 8600 accordinglyfurthermore follow, post upgrade procedure thai language import, applying support package / hr-support package 7, 6c srx thai            23/apr/2001 caution, 6c sr1 thai language disc, 6c sr2 thai language disc, support packages / hr-support packages, start importing thai language data, post installation procedure update tcp0c
Related Notes : 
       
| 487971 | Migration Tools CV Thailand 40B to R/3 Enterprise | 
| 426319 | SAPscript: Thai on AS/400 | 
| 420371 | Add. info on upgrading to Basis 4.6C SR2 (NDI upgrade) | 
| 417453 | PC editor: Systems with blended code page | 
| 390062 | Additional information about upgrading to 4.6C SR2 | 
| 387745 | Inst.: 4.6C SR2 R/3 Inst. on Windows (general) | 
| 387074 | INST: R/3 4.6C SR2 Installation on UNIX | 
| 377059 | Control codes converted to points | 
| 371248 | Thai language problem after 4.6C/D upgrade/installation | 
| 331856 | Migration Tools for Country Version Thailand to 46C | 
| 329622 | Additions: Upgrading to Basis 4.6C SR1 (NDI upgrade) | 
| 328409 | Inst: 4.6C SR1 R/3 Inst. on Windows NT (general) | 
| 327285 | Additions to upgrade to 4.6C SR1 | 
| 325761 | Error:missing semi-colon in T015Z Thai translation | 
| 314835 | Error in country specific functions Thailand | 
| 313107 | INST: 4.6C SR1 R/3 Installation on UNIX | 
| 302362 | Generic language import: Termination for DB MSSQL | 
| 208830 | Inst: 4.6C R/3 inst. on Windows NT (general) | 
| 201144 | INST: 4.6C R/3 Installation on UNIX | 
| 195443 | Current note on language import 4.6C | 
| 192949 | Additional info for upgrade to 4.6C | 
| 45463 | Thai installation procedure | 
| 42305 | RSCPINST (I18N configuration tool) |