title: Using git for VS2010 project: Can't add file *.opensdf
body: <p>I'm using git to track a C++ project in VS2010. I'm using ignore patterns found on stackoverflow, which usually do not exclude the *.opensdf file. Unfortunately, when trying to commit the file, I get the following error:  </p>
  
  <pre><code>error: open("foo.opensdf"): Permission denied
  error: unable to index file foo.opensdf
  fatal: adding files failed
  </code></pre>
  
  <p>Why do I get this error and how can it be avoided? Since I'm quite a newbie with VS2010, what is the use of this file?</p>
  
  <p>Thanks!    </p>
  
  <p>mort</p>