diff --git a/docs/LanguageExtensions.html b/docs/LanguageExtensions.html
index 7ee8f01..528315b 100644
--- a/docs/LanguageExtensions.html
+++ b/docs/LanguageExtensions.html
@@ -599,6 +599,7 @@
   <li><code>__is_polymorphic</code> (GNU, Microsoft)</li>
   <li><code>__is_union</code> (GNU, Microsoft)</li>
   <li><code>__is_literal(type)</code>: Determines whether the given type is a literal type</li>
+  <li><code>__underlying_type(type)</code>: Retrieves the underlying type for a given <code>enum</code> type. This trait is required to implement the C++0x standard library.</li>
 </ul>
 
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