Plain text files do not have a charset tag. If the files are not in UTF-8 encoding, encoding conversion is needed. For example, to convert a plain text file encoded in Traditional Chinese big5 to UTF-8, execute the following command:
iconv -f big5 -t UTF-8 inputfilename > outputfilename
You can also use the File System Examiner for the encoding conversion.
You can use the Text Editor to read and write character encoding text automatically or by specifying an encoding explicitly when opening or saving a file.
To start Text Editor, click Launch, then choose Applications->Accessories->Text Editor.