title: Excel file formats supported by POI?
body: <p>I have gone through POI documentation and did not find any list of all the supported file formats. The <a href="https://github.com/apache/poi/tree/trunk/test-data/spreadsheet" rel="nofollow noreferrer">test data directory</a> on github also does not contain all file formats that are supported by POI. </p>
  
  <p>I have tried out most of the format myself using the API but some of the old formats like <strong>.xlc and xlw</strong> I am not able to try out.
  Any help regarding this is appreciated.    </p>