R code to convert TCVN3 to Unicode UTF-8 using command line tool uconv.exe (unikey.org)
uvconv [file] [OPTIONS]\n" file: Input file [Default: stdin - keyboard input]" Options -h --help Print Help and exit -f --from Input charset [Default: TCVN3] -t --to Output charset [Default: UTF-8] -o --output Output file [Default: stdout - console output] -l --list Print charset list and exit -m --mviqr Mixed VIQR characters present in input -s --sviqr Strict VIQR input, converting everything, not checking escapes for URLs, etc. (a bit faster, but not recommended). Example: uvconv in.txt -f VNI -t UTF-8 -o out.txt