title: What does 'useLegacyV2RuntimeActivationPolicy' do in the .NET 4 config?
body: <p>While converting a project that used SlimDX, and therefore has unmanaged code, to .NET 4.0 I ran into the following error:</p>
  
  <blockquote>
    <p>Mixed mode assembly is built against version 'v2.0.50727' of the runtime and cannot be loaded in the 4.0 runtime without additional configuration information.</p>
  </blockquote>
  
  <p>Googling around gave me the solution, which is to add this to the applications config:</p>
  
  <pre><code>&lt;configuration&gt;
    &lt;startup useLegacyV2RuntimeActivationPolicy="true"&gt;
      &lt;supportedRuntime version="v4.0"/&gt;
    &lt;/startup&gt;
  &lt;/configuration&gt;
  </code></pre>
  
  <p>My question is, what is the <code>useLegacyV2RuntimeActivationPolicy</code> doing? I can't find any documentation about it.</p>