diff --git a/include/boost/iterator/iterator_traits.hpp b/include/boost/iterator/iterator_traits.hpp
index 856641c..39e08c0 100644
--- a/include/boost/iterator/iterator_traits.hpp
+++ b/include/boost/iterator/iterator_traits.hpp
@@ -10,7 +10,8 @@
 
 namespace boost { 
 
-// Obsolete. Remove.
+// Macro for supporting old compilers, no longer needed but kept
+// for backwards compatibility (it was documented).
 #define BOOST_ITERATOR_CATEGORY iterator_category