Not autodetected sjis encoding

[nnseva]

The following file (applied as base64-encoded)

R0VPR0NTWyJHQ1NfVG9reW9fTVMiLERBVFVNWyJEX1Rva3lvIixTUEhFUk9JRFsiQmVzc2VsXzE4
NDEiLDYzNzczOTcuMTU1LDI5OS4xNTI4MTI4XV0sUFJJTUVNWyJHcmVlbndpY2giLDAuMF0sVU5J
VFsiPINKg1iDXoOAPiIsNC44NDgxMzY4MTEwOTUzNTllLTAwOV1d

encoding has not been determined by the enca

seva@SEVA-WORK:~/$ enca --version
enca 1.19

Features: +librecode-interface +iconv-interface +external-converter +language-detection -locale-alias +target-charset-auto +ENCAOPT 

Copyright (C) 2000-2005 David Necas (Yeti) (<[email protected]>),
              2005 Zuxy Meng (<[email protected]>).

Enca is free software; it can be copied and/or modified under the terms of
version 2 of GNU General Public License, run `enca --license' to see the full
license text.  There is NO WARRANTY; not even for MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.

The kate (KDE-bindled) editor has successfully recognized sjis encoding on the same file

The recode application has been installed and successfully decodes the source file when the encoding is explicitly passed:

seva@SEVA-WORK:~/$ base64 -d | recode SJIS..utf-8
R0VPR0NTWyJHQ1NfVG9reW9fTVMiLERBVFVNWyJEX1Rva3lvIixTUEhFUk9JRFsiQmVzc2VsXzE4
NDEiLDYzNzczOTcuMTU1LDI5OS4xNTI4MTI4XV0sUFJJTUVNWyJHcmVlbndpY2giLDAuMF0sVU5J
VFsiPINKg1iDXoOAPiIsNC44NDgxMzY4MTEwOTUzNTllLTAwOV1d
GEOGCS["GCS_Tokyo_MS",DATUM["D_Tokyo",SPHEROID["Bessel_1841",6377397.155,299.1528128]],PRIMEM["Greenwich",0.0],UNIT["<カスタム>",4.848136811095359e-009]]