title: Using a ISO language code when making subtitles default
body: <p>I'm making a program using AHK and MKVtoolnix to remove audio file and subtitles quickly here's the code:</p>
  
  <pre><code>FOR /F "delims=*" %%A IN ('dir /b *.MKV') DO "H:\Not School\Programs\mkvtoolnix-32-bit-15.0.0\mkvtoolnix\mkvmerge.exe" -o "%OutputVar%\%%A" -a %AT% -s %ST% --default-subtitle ???  "%InputVar%\%%A
  </code></pre>
  
  <p>When I put an ISO code in where the question marks are I get an error, and I'd like to have it the same as %ST% which will be the subtitles I'm keeping, is there anyway round this or am I going to have to add a input box for subtitle track?</p>