title: Why don't substrings work with command line arguments?
body: <p>In a Windows batch file, the following will work to extract all of <code>%1</code> except the last 4 characters:</p>
  <pre><code>set foo=%1
  set x=%foo:~,-4%
  </code></pre>
  <p>But this will not work:</p>
  <pre><code>set x=%1:~,-4%
  </code></pre>
  <p>Why is this?</p>