title: What controls the ProductVersion setting in .csproj files?
body: <p>Every now and then our source control engine indicates that the <code>ProductVersion</code> in a .csproj file has changed. We're using VS2008 SP1.</p>
  
  <p>Looking through the codebase I can see two versions reported:</p>
  
  <pre><code>&lt;ProductVersion&gt;9.0.30729&lt;/ProductVersion&gt;
  </code></pre>
  
  <p>and</p>
  
  <pre><code>&lt;ProductVersion&gt;9.0.21022&lt;/ProductVersion&gt;
  </code></pre>
  
  <p>Does anyone know why and when Visual Studio decides to change this setting, and to what these two version numbers refer?</p>