<div class="content"><p>The IsUniqueKey method is received by the server in an
RPC_REQUEST packet. In response, the server returns whether the specified
property must be unique compared to all other properties of the peer collection
of <a href="59774887-09e3-4de5-ad8e-4794f404b123" data-linktype="relative-path">IAppHostElement</a>
objects. In other words, it applies only to properties that are members of the
collection of IAppHostElement objects.</p><dl>
<dd>
<div><pre> [propget] HRESULT IsUniqueKey(
   [out, retval] VARIANT_BOOL* pfIsUniqueKey
 );
</pre></div>
</dd></dl><p><b>pfIsUniqueKey: </b>A Boolean value that states
whether an attribute is required to be unique in the specified collection of
the parent IAppHostElement.</p><p><b>Return Values: </b>The server MUST return zero if
it successfully processes the message that is received from the client. If
processing fails, the server MUST return a nonzero <a href="../ms-dtyp/a9046ed2-bfb2-4d56-a719-2824afce59ac" data-linktype="relative-path">HRESULT</a>
code as defined in <a href="../ms-erref/1bc92ddf-b79e-413c-bbaa-99a5281a6c90" data-linktype="relative-path">[MS-ERREF]</a>.
The following table describes the error conditions that MUST be handled and the
corresponding error codes. A server MAY return additional
implementation-specific error codes.</p><dl>
<dd>
<table><thead>
  <tr>
   <th>
   <p>Return value/code</p>
   </th>
   <th>
   <p>Description</p>
   </th>
  </tr>
 </thead><tbody><tr>
  <td>
  <p>0X00000000</p>
  <p>NO_ERROR</p>
  </td>
  <td>
  <p>The operation completed successfully.</p>
  </td>
 </tr><tr>
  <td>
  <p>0X80070057</p>
  <p>ERROR_INVALID_PARAMETER</p>
  </td>
  <td>
  <p>One or more parameters are incorrect or null.</p>
  </td>
 </tr></tbody></table>
</dd></dl><p> </p></div>