title: Windows SDK 8: Confusion Regarding Install Location, folder nomenclature and WindowsSdkDir_old env variable
body: <p>While working with Visual Studio 2012 build system, unlike previous SDK Versions, I realized, the Windows SDK 8 gets installed into two separate locations</p>
  
  <pre><code>C:\Program Files (x86)\Windows Kits\8.0\ - Everything sans .NET 4.5 
  </code></pre>
  
  <p>as mentioned in</p>
  
  <pre><code>HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Microsoft SDKs\Windows\v8.0\InstallationFolder
  </code></pre>
  
  <p>and </p>
  
  <pre><code>C:\Program Files (x86)\Microsoft SDKs\Windows\v8.0A\
  </code></pre>
  
  <p>as mentioned in</p>
  
  <pre><code>HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Microsoft SDKs\Windows\v8.0A\InstallationFolder
  </code></pre>
  
  <p>It seems Microsoft have segregated the Core SDK from .NET Framework</p>
  
  <p>I also tried to correlate with how</p>
  
  <pre><code> *    %VS_HOME%\VC\bin\vcvars32.bat
   *    %VS_HOME%\VC\bin\x86_amd64\vcvarsx86_amd64.bat
   *    %VS_HOME%\VC\bin\amd64\vcvarsamd64.bat
  </code></pre>
  
  <p>is working now, and it seems, it refers the .NET 4.5 Framework Location with WindowsSdkDir_old</p>
  
  <p>Other interesting things I realized were</p>
  
  <ol>
  <li>%WindowsSdkDir%\Include has three hierarchy: Shared, um and WinRT</li>
  <li>Windows SDK got per-installed with VS 2010 but with VS 2012 I had to install it separately.</li>
  </ol>
  
  <p>SO my question is</p>
  
  <ol>
  <li>Is there any specific reason to separate .NET 4.5 from the core SDK?</li>
  <li>What is the reason to refer the .NET 4.5 Install Location as WindowsSdkDir_old</li>
  <li>Why Windows SDK 8.0A is not part of VS 2012 Install Package?</li>
  <li>Can I continue to use Windows SDK 7.1A with VS 2012?</li>
  <li>What is the significance of the include path %WindowsSdkDir%\Include[Shared| um | WInRT] ?</li>
  </ol>