diff --git a/include/boost/mpl/aux_/preprocessor/is_seq.hpp b/include/boost/mpl/aux_/preprocessor/is_seq.hpp
new file mode 100644
index 0000000..c642b8a
--- /dev/null
+++ b/include/boost/mpl/aux_/preprocessor/is_seq.hpp
@@ -0,0 +1,57 @@
+
+#ifndef BOOST_MPL_AUX_PREPROCESSOR_IS_SEQ_HPP_INCLUDED
+#define BOOST_MPL_AUX_PREPROCESSOR_IS_SEQ_HPP_INCLUDED
+
+// + file: boost/mpl/aux_/preprocessor/is_seq.hpp
+// + last modified: 03/may/03
+
+// Copyright (c) 2003
+// Paul Mensonides, Aleksey Gurtovoy
+//
+// Permission to use, copy, modify, distribute and sell this software
+// and its documentation for any purpose is hereby granted without fee, 
+// provided that the above copyright notice appears in all copies and 
+// that both the copyright notice and this permission notice appear in 
+// supporting documentation. No representations are made about the 
+// suitability of this software for any purpose. It is provided "as is" 
+// without express or implied warranty.
+//
+// See http://www.boost.org/libs/mpl for documentation.
+
+#include "boost/preprocessor/seq/size.hpp"
+#include "boost/preprocessor/arithmetic/dec.hpp"
+#include "boost/preprocessor/punctuation/paren.hpp"
+#include "boost/preprocessor/cat.hpp"
+#include "boost/preprocessor/config/config.hpp"
+
+// returns 1 if 'seq' is a PP-sequence, 0 otherwise:
+//
+//   BOOST_PP_ASSERT( BOOST_PP_NOT( BOOST_MPL_PP_IS_SEQ( int ) ) )
+//   BOOST_PP_ASSERT( BOOST_MPL_PP_IS_SEQ( (int) ) )
+//   BOOST_PP_ASSERT( BOOST_MPL_PP_IS_SEQ( (1)(2) ) )
+
+#if BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_BCC()
+
+#   define BOOST_MPL_PP_IS_SEQ(seq) BOOST_PP_DEC( BOOST_PP_SEQ_SIZE( BOOST_MPL_PP_IS_SEQ_(seq) ) )
+#   define BOOST_MPL_PP_IS_SEQ_(seq) BOOST_MPL_PP_IS_SEQ_SEQ_( BOOST_MPL_PP_IS_SEQ_SPLIT_ seq )
+#   define BOOST_MPL_PP_IS_SEQ_SEQ_(x) (x)
+#   define BOOST_MPL_PP_IS_SEQ_SPLIT_(unused) unused)((unused)
+
+#else
+
+#   if BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MWCC()
+#       define BOOST_MPL_PP_IS_SEQ(seq) BOOST_MPL_PP_IS_SEQ_MWCC_((seq))
+#       define BOOST_MPL_PP_IS_SEQ_MWCC_(args) BOOST_MPL_PP_IS_SEQ_ ## args
+#   else
+#       define BOOST_MPL_PP_IS_SEQ(seq) BOOST_MPL_PP_IS_SEQ_(seq)
+#   endif
+
+#   define BOOST_MPL_PP_IS_SEQ_(seq) BOOST_PP_CAT(BOOST_MPL_PP_IS_SEQ_, BOOST_MPL_PP_IS_SEQ_0 seq BOOST_PP_RPAREN())
+#   define BOOST_MPL_PP_IS_SEQ_0(x) BOOST_MPL_PP_IS_SEQ_1(x
+#   define BOOST_MPL_PP_IS_SEQ_ALWAYS_0(unused) 0
+#   define BOOST_MPL_PP_IS_SEQ_BOOST_MPL_PP_IS_SEQ_0 BOOST_MPL_PP_IS_SEQ_ALWAYS_0(
+#   define BOOST_MPL_PP_IS_SEQ_BOOST_MPL_PP_IS_SEQ_1(unused) 1
+
+#endif
+
+#endif // BOOST_MPL_AUX_PREPROCESSOR_IS_SEQ_HPP_INCLUDED
diff --git a/include/boost/mpl/aux_/preprocessor/token_equal.hpp b/include/boost/mpl/aux_/preprocessor/token_equal.hpp
new file mode 100644
index 0000000..2a209ac
--- /dev/null
+++ b/include/boost/mpl/aux_/preprocessor/token_equal.hpp
@@ -0,0 +1,59 @@
+
+#ifndef BOOST_MPL_AUX_PREPROCESSOR_TOKEN_EQUAL_HPP_INCLUDED
+#define BOOST_MPL_AUX_PREPROCESSOR_TOKEN_EQUAL_HPP_INCLUDED
+
+// + file: boost/mpl/aux_/preprocessor/token_equal.hpp
+// + last modified: 03/may/03
+
+// Copyright (c) 2003
+// Paul Mensonides, Aleksey Gurtovoy
+//
+// Permission to use, copy, modify, distribute and sell this software
+// and its documentation for any purpose is hereby granted without fee, 
+// provided that the above copyright notice appears in all copies and 
+// that both the copyright notice and this permission notice appear in 
+// supporting documentation. No representations are made about the 
+// suitability of this software for any purpose. It is provided "as is" 
+// without express or implied warranty.
+//
+// See http://www.boost.org/libs/mpl for documentation.
+
+#include "boost/mpl/aux_/preprocessor/is_seq.hpp"
+
+#include "boost/preprocessor/if.hpp"
+#include "boost/preprocessor/logical/bitand.hpp"
+#include "boost/preprocessor/logical/compl.hpp"
+#include "boost/preprocessor/tuple/eat.hpp"
+#include "boost/preprocessor/cat.hpp"
+
+// compares tokens 'a' and 'b' for equality:
+//
+//   #define BOOST_MPL_PP_TOKEN_EQUAL_apple(x) x
+//   #define BOOST_MPL_PP_TOKEN_EQUAL_orange(x) x
+//
+//   BOOST_PP_ASSERT( BOOST_PP_NOT( BOOST_MPL_PP_TOKEN_EQUAL(apple, abc) ) )
+//   BOOST_PP_ASSERT( BOOST_PP_NOT( BOOST_MPL_PP_TOKEN_EQUAL(abc, apple) ) )
+//   BOOST_PP_ASSERT( BOOST_PP_NOT( BOOST_MPL_PP_TOKEN_EQUAL(apple, orange) ) )
+//   BOOST_PP_ASSERT( BOOST_MPL_PP_TOKEN_EQUAL(apple, apple) )
+//   BOOST_PP_ASSERT( BOOST_MPL_PP_TOKEN_EQUAL(orange, orange) )
+
+#define BOOST_MPL_PP_TOKEN_EQUAL(a, b) \
+    BOOST_PP_IIF( \
+        BOOST_PP_BITAND( \
+              BOOST_MPL_PP_IS_SEQ( BOOST_PP_CAT(BOOST_MPL_PP_TOKEN_EQUAL_, a)((unused)) ) \
+            , BOOST_MPL_PP_IS_SEQ( BOOST_PP_CAT(BOOST_MPL_PP_TOKEN_EQUAL_, b)((unused)) ) \
+            ) \
+        , BOOST_MPL_PP_TOKEN_EQUAL_I \
+        , 0 BOOST_PP_TUPLE_EAT(2) \
+        )(a, b) \
+/**/
+
+#define BOOST_MPL_PP_TOKEN_EQUAL_I(a, b) \
+    BOOST_PP_COMPL(BOOST_MPL_PP_IS_SEQ( \
+        BOOST_MPL_PP_TOKEN_EQUAL_ ## a( \
+            BOOST_MPL_PP_TOKEN_EQUAL_ ## b \
+            )((unused)) \
+        )) \
+/**/
+
+#endif // BOOST_MPL_AUX_PREPROCESSOR_TOKEN_EQUAL_HPP_INCLUDED
diff --git a/include/boost/mpl/aux_/test.hpp b/include/boost/mpl/aux_/test.hpp
new file mode 100644
index 0000000..755a3e0
--- /dev/null
+++ b/include/boost/mpl/aux_/test.hpp
@@ -0,0 +1,27 @@
+
+#ifndef BOOST_MPL_AUX_TEST_HPP_INCLUDED
+#define BOOST_MPL_AUX_TEST_HPP_INCLUDED
+
+// + file: boost/mpl/aux_/test.hpp
+// + last modified: 04/may/03
+
+// Copyright (c) 2002-03
+// Aleksey Gurtovoy
+//
+// Permission to use, copy, modify, distribute and sell this software
+// and its documentation for any purpose is hereby granted without fee, 
+// provided that the above copyright notice appears in all copies and 
+// that both the copyright notice and this permission notice appear in 
+// supporting documentation. No representations are made about the 
+// suitability of this software for any purpose. It is provided "as is" 
+// without express or implied warranty.
+//
+// See http://www.boost.org/libs/mpl for documentation.
+
+#include "boost/mpl/aux_/test/assert.hpp"
+#include "boost/mpl/aux_/test/data.hpp"
+#include "boost/mpl/aux_/test/test_case.hpp"
+#include "boost/mpl/aux_/test/for_each.hpp"
+#include "boost/mpl/aux_/config/msvc_typename.hpp"
+
+#endif // BOOST_MPL_AUX_TEST_HPP_INCLUDED
diff --git a/include/boost/mpl/aux_/yes_no.hpp b/include/boost/mpl/aux_/yes_no.hpp
index b7a1999..59395a7 100644
--- a/include/boost/mpl/aux_/yes_no.hpp
+++ b/include/boost/mpl/aux_/yes_no.hpp
@@ -1,10 +1,12 @@
-//-----------------------------------------------------------------------------
-// boost mpl/aux_/yes_no.hpp header file
-// See http://www.boost.org for updates, documentation, and revision history.
-//-----------------------------------------------------------------------------
-//
-// Copyright (c) 2001-02
-// Peter Dimov, Aleksey Gurtovoy
+
+#ifndef BOOST_MPL_AUX_YES_NO_HPP_INCLUDED
+#define BOOST_MPL_AUX_YES_NO_HPP_INCLUDED
+
+// + file: boost/mpl/aux_/yes_no.hpp
+// + last modified: 05/may/03
+
+// Copyright (c) 2000-03
+// Aleksey Gurtovoy
 //
 // Permission to use, copy, modify, distribute and sell this software
 // and its documentation for any purpose is hereby granted without fee, 
@@ -13,19 +15,24 @@
 // supporting documentation. No representations are made about the 
 // suitability of this software for any purpose. It is provided "as is" 
 // without express or implied warranty.
+//
+// See http://www.boost.org/libs/mpl for documentation.
 
-#ifndef BOOST_MPL_AUX_YES_NO_HPP_INCLUDED
-#define BOOST_MPL_AUX_YES_NO_HPP_INCLUDED
-
-namespace boost {
-namespace mpl {
-namespace aux {
+namespace boost { namespace mpl { namespace aux {
 
 typedef char (&no_tag)[1];
 typedef char (&yes_tag)[2];
 
-} // namespace aux
-} // namespace mpl
-} // namespace boost 
+template< bool C_ > struct yes_no_tag
+{
+    typedef no_tag type;
+};
+
+template<> struct yes_no_tag<true>
+{
+    typedef yes_tag type;
+};
+
+}}}
 
 #endif // BOOST_MPL_AUX_YES_NO_HPP_INCLUDED
diff --git a/include/boost/mpl/if.hpp b/include/boost/mpl/if.hpp
index 559f16e..15faa35 100644
--- a/include/boost/mpl/if.hpp
+++ b/include/boost/mpl/if.hpp
@@ -115,7 +115,7 @@ struct if_
 // on the result of is_reference.
 
 template <class T1, class T2, class T3, class T4> struct bind3;
-template <template <class T1, class T2, class T3> class> struct quote3;
+template <template <class T1, class T2, class T3> class F> struct quote3;
 
 namespace aux
 {
diff --git a/include/boost/mpl/insert.hpp b/include/boost/mpl/insert.hpp
index 64c6f56..f248085 100644
--- a/include/boost/mpl/insert.hpp
+++ b/include/boost/mpl/insert.hpp
@@ -28,14 +28,14 @@ namespace mpl {
 
 template<
       typename BOOST_MPL_AUX_VOID_SPEC_PARAM(Sequence)
-    , typename BOOST_MPL_AUX_VOID_SPEC_PARAM(Pos)
+    , typename BOOST_MPL_AUX_VOID_SPEC_PARAM(Pos_or_T)
     , typename BOOST_MPL_AUX_VOID_SPEC_PARAM(T)
     >
 struct insert
     : insert_traits< typename BOOST_MPL_AUX_SEQUENCE_TAG(Sequence) >
-        ::template algorithm< Sequence,Pos,T >
+        ::template algorithm< Sequence,Pos_or_T,T >
 {
-    BOOST_MPL_AUX_LAMBDA_SUPPORT(3,insert,(Sequence,Pos,T))
+    BOOST_MPL_AUX_LAMBDA_SUPPORT(3,insert,(Sequence,Pos_or_T,T))
 };
 
 BOOST_MPL_AUX_VOID_SPEC(3, insert)
diff --git a/include/boost/mpl/insert_fwd.hpp b/include/boost/mpl/insert_fwd.hpp
index 5fc15ce..726105a 100644
--- a/include/boost/mpl/insert_fwd.hpp
+++ b/include/boost/mpl/insert_fwd.hpp
@@ -1,9 +1,11 @@
-//-----------------------------------------------------------------------------
-// boost mpl/insert_fwd.hpp header file
-// See http://www.boost.org for updates, documentation, and revision history.
-//-----------------------------------------------------------------------------
-//
-// Copyright (c) 2000-02
+
+#ifndef BOOST_MPL_INSERT_FWD_HPP_INCLUDED
+#define BOOST_MPL_INSERT_FWD_HPP_INCLUDED
+
+// + file: boost/mpl/insert_fwd.hpp
+// + last modified: 02/may/03
+
+// Copyright (c) 2000-03
 // Aleksey Gurtovoy
 //
 // Permission to use, copy, modify, distribute and sell this software
@@ -13,15 +15,14 @@
 // supporting documentation. No representations are made about the 
 // suitability of this software for any purpose. It is provided "as is" 
 // without express or implied warranty.
-
-#ifndef BOOST_MPL_INSERT_FWD_HPP_INCLUDED
-#define BOOST_MPL_INSERT_FWD_HPP_INCLUDED
+//
+// See http://www.boost.org/libs/mpl for documentation.
 
 namespace boost {
 namespace mpl {
 
 template< typename Tag > struct insert_traits;
-template< typename Sequence, typename Pos, typename T > struct insert;
+template< typename Sequence, typename Pos_or_T, typename T > struct insert;
 
 } // namespace mpl
 } // namespace boost
diff --git a/include/boost/mpl/set/aux_/insert_impl.hpp b/include/boost/mpl/set/aux_/insert_impl.hpp
new file mode 100644
index 0000000..b0af04c
--- /dev/null
+++ b/include/boost/mpl/set/aux_/insert_impl.hpp
@@ -0,0 +1,60 @@
+
+#ifndef BOOST_MPL_SET_AUX_INSERT_IMPL_HPP_INCLUDED
+#define BOOST_MPL_SET_AUX_INSERT_IMPL_HPP_INCLUDED
+
+// + file: boost/mpl/aux_/insert_impl.hpp
+// + last modified: 05/may/03
+
+// Copyright (c) 2002-03
+// David Abrahams, Aleksey Gurtovoy
+//
+// Permission to use, copy, modify, distribute and sell this software
+// and its documentation for any purpose is hereby granted without fee, 
+// provided that the above copyright notice appears in all copies and 
+// that both the copyright notice and this permission notice appear in 
+// supporting documentation. No representations are made about the 
+// suitability of this software for any purpose. It is provided "as is" 
+// without express or implied warranty.
+//
+// See http://www.boost.org/libs/mpl for documentation.
+
+#include "boost/mpl/set/aux_/has_key_impl.hpp"
+#include "boost/mpl/set/aux_/item.hpp"
+#include "boost/mpl/set/aux_/tag.hpp"
+#include "boost/mpl/insert_fwd.hpp"
+#include "boost/mpl/identity.hpp"
+#include "boost/mpl/base.hpp"
+#include "boost/mpl/apply_if.hpp"
+
+#include "boost/type_traits/is_same.hpp"
+
+namespace boost {
+namespace mpl {
+
+template<>
+struct insert_traits< aux::set_tag >
+{
+    template< typename Set, typename T, typename unused_ > struct algorithm
+        : apply_if< 
+              has_key_impl<aux::set_tag>::apply<Set,T>
+            , apply_if< 
+                  is_same< T,typename Set::last_masked > 
+                , base<Set>
+                , identity<Set>
+                >
+            , identity< s_item<T,Set> >
+            >
+/*
+    : eval< if_<
+          has_key<Set,T>
+        , if_< is_same< T,typename Set::last_masked >, base< arg<Set> >, Set >
+        , Set
+        > >
+*/
+    {
+    };
+};
+
+}}
+
+#endif // BOOST_MPL_SET_AUX_INSERT_IMPL_HPP_INCLUDED
diff --git a/include/boost/mpl/set/aux_/item.hpp b/include/boost/mpl/set/aux_/item.hpp
index 6966a79..ff81df6 100644
--- a/include/boost/mpl/set/aux_/item.hpp
+++ b/include/boost/mpl/set/aux_/item.hpp
@@ -19,6 +19,7 @@
 // See http://www.boost.org/libs/mpl for documentation.
 
 #include "boost/mpl/long.hpp"
+#include "boost/mpl/void_fwd.hpp"
 #include "boost/mpl/set/aux_/set0.hpp"
 #include "boost/mpl/aux_/yes_no.hpp"
 #include "boost/mpl/aux_/type_wrapper.hpp"
@@ -61,8 +62,9 @@ template< typename T, typename Base >
 struct s_item
     : Base
 {
-    typedef T item;
-    typedef Base base;
+    typedef void_   last_masked;
+    typedef T       item;
+    typedef Base    base;
     
     BOOST_STATIC_CONSTANT(long, order = Base::order + 1);
 
@@ -87,6 +89,7 @@ template< typename T, typename Base >
 struct s_mask
     : Base
 {
+    typedef T last_masked;
 #if BOOST_WORKAROUND(__GNUC__, > 2) && BOOST_WORKAROUND(__GNUC__, BOOST_TESTED_AT(3))
     // to make GCC happy
     friend aux::no_tag operator%<>(s_mask const&, aux::type_wrapper<T>*);
diff --git a/include/boost/mpl/set/aux_/set0.hpp b/include/boost/mpl/set/aux_/set0.hpp
index 529f5e0..e791fb3 100644
--- a/include/boost/mpl/set/aux_/set0.hpp
+++ b/include/boost/mpl/set/aux_/set0.hpp
@@ -18,7 +18,7 @@
 //
 // See http://www.boost.org/libs/mpl for documentation.
 
-#include "boost/mpl/void.hpp"
+#include "boost/mpl/void_fwd.hpp"
 #include "boost/mpl/set/aux_/tag.hpp"
 #include "boost/mpl/aux_/config/static_constant.hpp"
 
@@ -27,8 +27,10 @@ namespace mpl {
 
 template< int p_ = 0 > struct set0
 {
-    typedef aux::set_tag tag;
-    typedef void_ item;
+    typedef aux::set_tag    tag;
+    typedef void_           last_masked;
+    typedef void_           item;
+
     BOOST_STATIC_CONSTANT(long, order = 0);
 };
 
diff --git a/include/boost/mpl/set/set0.hpp b/include/boost/mpl/set/set0.hpp
index 4967546..5a8012e 100644
--- a/include/boost/mpl/set/set0.hpp
+++ b/include/boost/mpl/set/set0.hpp
@@ -27,6 +27,8 @@
 //#include "boost/mpl/set/aux_/O1_size.hpp"
 //#include "boost/mpl/set/aux_/size.hpp"
 //#include "boost/mpl/set/aux_/empty.hpp"
+//#include "boost/mpl/set/aux_/empty.hpp"
+#include "boost/mpl/set/aux_/insert_impl.hpp"
 #include "boost/mpl/set/aux_/order_impl.hpp"
 #include "boost/mpl/set/aux_/has_key_impl.hpp"
 #include "boost/mpl/set/aux_/begin_end_impl.hpp"
diff --git a/include/boost/mpl/void.hpp b/include/boost/mpl/void.hpp
index f0cecae..977c521 100644
--- a/include/boost/mpl/void.hpp
+++ b/include/boost/mpl/void.hpp
@@ -1,24 +1,27 @@
-//-----------------------------------------------------------------------------
-// boost mpl/void.hpp header file
-// See http://www.boost.org for updates, documentation, and revision history.
-//-----------------------------------------------------------------------------
-//
-// Copyright (c) 2001-02
-// Peter Dimov, Aleksey Gurtovoy
-//
-// Permission to use, copy, modify, distribute and sell this software
-// and its documentation for any purpose is hereby granted without fee,
-// provided that the above copyright notice appears in all copies and
-// that both the copyright notice and this permission notice appear in
-// supporting documentation. No representations are made about the
-// suitability of this software for any purpose. It is provided "as is"
-// without express or implied warranty.
 
 #ifndef BOOST_MPL_VOID_HPP_INCLUDED
 #define BOOST_MPL_VOID_HPP_INCLUDED
 
+// + file: boost/mpl/void.hpp
+// + last modified: 05/may/03
+
+// Copyright (c) 2001-03
+// Peter Dimov, Aleksey Gurtovoy
+//
+// Permission to use, copy, modify, distribute and sell this software
+// and its documentation for any purpose is hereby granted without fee, 
+// provided that the above copyright notice appears in all copies and 
+// that both the copyright notice and this permission notice appear in 
+// supporting documentation. No representations are made about the 
+// suitability of this software for any purpose. It is provided "as is" 
+// without express or implied warranty.
+//
+// See http://www.boost.org/libs/mpl for documentation.
+
+#include "boost/mpl/void_fwd.hpp"
 #include "boost/mpl/bool.hpp"
-#include "boost/config.hpp"
+#include "boost/mpl/aux_/config/msvc.hpp"
+#include "boost/mpl/aux_/config/workaround.hpp"
 
 namespace boost {
 namespace mpl {
@@ -33,7 +36,7 @@ template< typename T >
 struct is_void_
     : false_
 {
-#if defined(BOOST_MSVC) && BOOST_MSVC < 1300
+#if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
     using false_::value;
 #endif
 };
@@ -42,7 +45,7 @@ template<>
 struct is_void_<void_>
     : true_
 {
-#if defined(BOOST_MSVC) && BOOST_MSVC < 1300
+#if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
     using true_::value;
 #endif
 };
diff --git a/include/boost/mpl/void_fwd.hpp b/include/boost/mpl/void_fwd.hpp
new file mode 100644
index 0000000..ab8b259
--- /dev/null
+++ b/include/boost/mpl/void_fwd.hpp
@@ -0,0 +1,29 @@
+
+#ifndef BOOST_MPL_VOID_FWD_HPP_INCLUDED
+#define BOOST_MPL_VOID_FWD_HPP_INCLUDED
+
+// + file: boost/mpl/void_fwd.hpp
+// + last modified: 05/may/03
+
+// Copyright (c) 2001-03
+// Aleksey Gurtovoy
+//
+// Permission to use, copy, modify, distribute and sell this software
+// and its documentation for any purpose is hereby granted without fee, 
+// provided that the above copyright notice appears in all copies and 
+// that both the copyright notice and this permission notice appear in 
+// supporting documentation. No representations are made about the 
+// suitability of this software for any purpose. It is provided "as is" 
+// without express or implied warranty.
+//
+// See http://www.boost.org/libs/mpl for documentation.
+
+namespace boost {
+namespace mpl {
+
+struct void_;
+
+} // namespace mpl
+} // namespace boost
+
+#endif // BOOST_MPL_VOID_FWD_HPP_INCLUDED