title: Determine excel file mime type
body: <p>I need  determine  what is type  of uploaded file</p>
  
  <p>When upload <code>.xlsx</code> file, this code:</p>
  
  <pre><code> echo $_FILES['uploaded_file']['type']."&lt;br&gt;";  
   echo mime_content_type($_FILES['uploaded_file']['tmp_name']);
  </code></pre>
  
  <p>returns:</p>
  
  <pre><code>application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
  application/vnd.ms-excel
  </code></pre>
  
  <p>As I know (from here <a href="https://stackoverflow.com/questions/3318288/php-xls-xlsx-ppt-pptx-headers">PHP xls, xlsx, ppt, pptx headers</a>), <code>application/vnd.ms-excel</code> is not <code>.xlsx</code>, but <code>.xls</code> file mime type.</p>
  
  <p>So, why returns <code>mime_content_type()</code> function <code>application/vnd.ms-excel</code> for <code>.xlsx</code> file? where the truth?</p>