title: Using one app setting variable definition in another app setting variable
body: <p>Is there a way to use one app setting variable definition in another app setting variable?</p>
  
  <p>This is an example, right now I have:</p>
  
  <pre><code>&lt;add key="P4RootDirectory" value="d:\p4\" /&gt;
  &lt;add key="P4LocalBranchSyncDirectory" value="d:\p4\sw\matt\" /&gt;
  </code></pre>
  
  <p>Ideally, I would like to have something like this</p>
  
  <pre><code>&lt;add key="P4RootDirectory" value="d:\p4\" /&gt;
  &lt;add key="P4LocalBranchSyncDirectory" value="%P4RootDirectory%sw\matt\" /&gt;
  </code></pre>
  
  <p>Is this not possible? Would I have to do this in my code?</p>