title: Displaytag is exporting CSV into a .xls file
body: <p>I export an Excel document with DisplayTag.  It saves as a .xls file to my Desktop.  When I open it with Excel, this error displays:</p>
  
  <p>"The file you are trying to open, 'filename.xls', is in a different format than specified by the file extension.  Verify that the file is not corrupted and is from a trusted source before opening the file."</p>
  
  <p>If I click "Yes", it displays just fine in Excel.  If I open this with Textpad, I see that it's a binary file, but it appears to just be "." delimited strings.  </p>
  
  <p>Any ideas what I might have done wrong, or how next to debug this?</p>
  
  <p><i>edit:</i>:</p>
  
  <p>If I change the extension to .txt, it's not a binary file; it's simply a list of delimited strings.</p>