native2ascii -reverse results with sun.io.UnknownCharacterException for the following encoding_names: 8859_6, Cp420, MacSymbol.
The input file is:
\u3092\u8aad\u307f\u8fbc\u3080\u3053\u3068\u304c\u3067\u304d\u307e\u305b\u3093\u3002

Also:
native2ascii -reverse -encoding JIS0208 input.txt native.txt
  where input file is as above, converts the file to following native-encoded characters:
$rFI$_9~$`$3$H$,$G$-$^$;$s!#

Then, trying to go back from native.txt, which is the output from above, to unicode characters, you get an output file that is identical to native.txt:
native2ascii -encoding JIS0208 native.txt output.txt
--------------------------------
Here's the script that exhibits the problem:
#!/bin/ksh

# Check if JAVA_HOME is defined in the environment, if not
# exit.

if [ -z $JAVA_HOME ]
then
  echo "JAVA_HOME should be defined and exported in TongaSetup.ini"
  exit 1
fi

if [ $# -eq 0 ]; then
  testWorkDir=./
  export CLASSPATH=.
else
  testWorkDir=${1}
  export CLASSPATH=${testWorkDir}
fi

if [ -f ${testWorkDir}native.* ]; then
  rm -f ${testWorkDir}native.*
fi

if [ -f ${testWorkDir}output.* ]; then
  rm -f ${testWorkDir}output.*
fi

if [ -f ${testWorkDir}unicode.* ]; then
  rm -f ${testWorkDir}unicode.*
fi

NATIVE2ASCII=${JAVA_HOME}/bin/native2ascii
ENCODING_LIST="8859_6 Cp420 JIS0208 MacSymbol";
KSHSTAT=0

for i in ${ENCODING_LIST}
do

  # convert a unicode encoded text (input.txt) to a native encoded text (native.txt)
  # according to the encoding_name supplied from the ENCODING_LIST.
  ${NATIVE2ASCII} -reverse -encoding ${i} ${testWorkDir}input.txt > ${testWorkDir}native.${i}.txt 2>&1

  # convert the native encoded text you just got back to a unicode encoded text (output.txt).
  ${NATIVE2ASCII} -encoding ${i} ${testWorkDir}native.${i}.txt > ${testWorkDir}output.${i}.txt 2>&1
  
  # find any discrepancies between the original unicode encoded text and the output unicode
  # encoded text. The two files should be identical.
  diff ${testWorkDir}input.txt ${testWorkDir}output.${i}.txt > ${testWorkDir}unicode.${i}.diff
  STATUS=$?
  echo ${i}':'${STATUS}' expecting '${i}':0'
  if [ ${STATUS} != "0" ]; then
    echo ' >>bad result-check revrese encoding on '${i}'.'
    KSHSTAT=1
  fi
 
done
 
exit ${KSHSTAT}

anat.kremer@Eng 1998-10-28