diff --git a/include/boost/unordered/detail/implementation.hpp b/include/boost/unordered/detail/implementation.hpp
index 65592760..d1d11977 100644
--- a/include/boost/unordered/detail/implementation.hpp
+++ b/include/boost/unordered/detail/implementation.hpp
@@ -46,10 +46,76 @@
 #include <tuple>
 #endif
 
+#if !defined(BOOST_NO_CXX11_HDR_TYPE_TRAITS)
+#include <type_traits>
+#endif
+
+////////////////////////////////////////////////////////////////////////////////
+// Configuration
+//
+// Unless documented elsewhere these configuration macros should be considered
+// an implementation detail, I'll try not to break them, but you never know.
+
+// BOOST_UNORDERED_EMPLACE_LIMIT = The maximum number of parameters in emplace
+// (not including things like hints). Don't set it to a lower value, as that
+// might break something.
+
+#if !defined BOOST_UNORDERED_EMPLACE_LIMIT
+#define BOOST_UNORDERED_EMPLACE_LIMIT 11
+#endif
+
+// BOOST_UNORDERED_USE_ALLOCATOR_TRAITS - Pick which version of
+// allocator_traits to use.
+//
+// 0 = Own partial implementation
+// 1 = std::allocator_traits
+// 2 = boost::container::allocator_traits
+
+#if !defined(BOOST_UNORDERED_USE_ALLOCATOR_TRAITS)
+#if !defined(BOOST_NO_CXX11_ALLOCATOR)
+#define BOOST_UNORDERED_USE_ALLOCATOR_TRAITS 1
+#elif defined(BOOST_MSVC)
+#if BOOST_MSVC < 1400
+// Use container's allocator_traits for older versions of Visual
+// C++ as I don't test with them.
+#define BOOST_UNORDERED_USE_ALLOCATOR_TRAITS 2
+#endif
+#endif
+#endif
+
+#if !defined(BOOST_UNORDERED_USE_ALLOCATOR_TRAITS)
+#define BOOST_UNORDERED_USE_ALLOCATOR_TRAITS 0
+#endif
+
+namespace boost {
+namespace unordered {
+namespace iterator_detail {
+template <typename Node> struct iterator;
+template <typename Node> struct c_iterator;
+template <typename Node, typename Policy> struct l_iterator;
+template <typename Node, typename Policy> struct cl_iterator;
+}
+}
+}
+
 namespace boost {
 namespace unordered {
 namespace detail {
 
+template <typename Types> struct table;
+template <typename NodePointer> struct bucket;
+struct ptr_bucket;
+template <typename Types> struct table_impl;
+template <typename Types> struct grouped_table_impl;
+
+template <typename A, typename T> struct unique_node;
+template <typename T> struct ptr_node;
+template <typename Types> struct table_impl;
+
+template <typename A, typename T> struct grouped_node;
+template <typename T> struct grouped_ptr_node;
+template <typename Types> struct grouped_table_impl;
+
 static const float minimum_max_load_factor = 1e-3f;
 static const std::size_t default_bucket_count = 11;
 struct move_tag
@@ -270,9 +336,6 @@ struct compressed
     // move_assign explicit.
     compressed& operator=(compressed const&);
 };
-}
-}
-}
 
 #if defined(BOOST_MSVC)
 #pragma warning(push)
@@ -282,13 +345,6 @@ struct compressed
 // will be default-initialized.
 #endif
 
-// Maximum number of arguments supported by emplace + 1.
-#define BOOST_UNORDERED_EMPLACE_LIMIT 11
-
-namespace boost {
-namespace unordered {
-namespace detail {
-
 ////////////////////////////////////////////////////////////////////////////
 // Bits and pieces for implementing traits
 
@@ -483,33 +539,6 @@ BOOST_PP_REPEAT_FROM_TO(
 #undef BOOST_UNORDERED_EARGS_MEMBER
 #undef BOOST_UNORDERED_EARGS_INIT
 
-#endif
-}
-}
-}
-
-////////////////////////////////////////////////////////////////////////////////
-//
-// Pick which version of allocator_traits to use
-//
-// 0 = Own partial implementation
-// 1 = std::allocator_traits
-// 2 = boost::container::allocator_traits
-
-#if !defined(BOOST_UNORDERED_USE_ALLOCATOR_TRAITS)
-#if !defined(BOOST_NO_CXX11_ALLOCATOR)
-#define BOOST_UNORDERED_USE_ALLOCATOR_TRAITS 1
-#elif defined(BOOST_MSVC)
-#if BOOST_MSVC < 1400
-// Use container's allocator_traits for older versions of Visual
-// C++ as I don't test with them.
-#define BOOST_UNORDERED_USE_ALLOCATOR_TRAITS 2
-#endif
-#endif
-#endif
-
-#if !defined(BOOST_UNORDERED_USE_ALLOCATOR_TRAITS)
-#define BOOST_UNORDERED_USE_ALLOCATOR_TRAITS 0
 #endif
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -517,14 +546,6 @@ BOOST_PP_REPEAT_FROM_TO(
 // Some utilities for implementing allocator_traits, but useful elsewhere so
 // they're always defined.
 
-#if !defined(BOOST_NO_CXX11_HDR_TYPE_TRAITS)
-#include <type_traits>
-#endif
-
-namespace boost {
-namespace unordered {
-namespace detail {
-
 ////////////////////////////////////////////////////////////////////////////
 // Integral_constrant, true_type, false_type
 //
@@ -1167,6 +1188,10 @@ struct rebind_wrap : boost::container::allocator_traits<
 
 #endif
 
+////////////////////////////////////////////////////////////////////////////
+// Functions used to construct nodes. Emulates variadic construction,
+// piecewise construction etc.
+
 namespace boost {
 namespace unordered {
 namespace detail {
@@ -1688,19 +1713,6 @@ construct_node_pair(Alloc& alloc, BOOST_FWD_REF(Key) k, BOOST_FWD_REF(Mapped) m)
 #pragma warning(pop)
 #endif
 
-namespace boost {
-namespace unordered {
-namespace detail {
-
-template <typename Types> struct table;
-template <typename NodePointer> struct bucket;
-struct ptr_bucket;
-template <typename Types> struct table_impl;
-template <typename Types> struct grouped_table_impl;
-}
-}
-}
-
 // The 'iterator_detail' namespace was a misguided attempt at avoiding ADL
 // in the detail namespace. It didn't work because the template parameters
 // were in detail. I'm not changing it at the moment to be safe. I might
@@ -1714,15 +1726,6 @@ namespace iterator_detail {
 //
 // all no throw
 
-template <typename Node> struct iterator;
-template <typename Node> struct c_iterator;
-template <typename Node, typename Policy> struct l_iterator;
-template <typename Node, typename Policy> struct cl_iterator;
-
-// Local Iterators
-//
-// all no throw
-
 template <typename Node, typename Policy>
 struct l_iterator : public std::iterator<std::forward_iterator_tag,
                         typename Node::value_type, std::ptrdiff_t,
@@ -2415,19 +2418,12 @@ struct rv_ref
 #define BOOST_UNORDERED_RV_REF(T)                                              \
     typename boost::unordered::detail::rv_ref<T>::type
 #endif
-}
-}
-}
 
 #if defined(BOOST_MSVC)
 #pragma warning(push)
 #pragma warning(disable : 4127) // conditional expression is constant
 #endif
 
-namespace boost {
-namespace unordered {
-namespace detail {
-
 ////////////////////////////////////////////////////////////////////////////
 // convert double to std::size_t
 
@@ -3122,18 +3118,12 @@ inline void table<Types>::reserve(std::size_t num_elements)
     rehash(static_cast<std::size_t>(
         std::ceil(static_cast<double>(num_elements) / mlf_)));
 }
-}
-}
-}
 
 #if defined(BOOST_MSVC)
 #pragma warning(pop)
 #endif
 
-namespace boost {
-namespace unordered {
-namespace detail {
-
+////////////////////////////////////////////////////////////////////////
 // key extractors
 //
 // no throw
@@ -3276,17 +3266,9 @@ template <class Key, class ValueType> struct map_extractor
     BOOST_UNORDERED_KEY_FROM_TUPLE(std::)
 #endif
 };
-}
-}
-}
 
-namespace boost {
-namespace unordered {
-namespace detail {
-
-template <typename A, typename T> struct unique_node;
-template <typename T> struct ptr_node;
-template <typename Types> struct table_impl;
+////////////////////////////////////////////////////////////////////////
+// Unique nodes
 
 template <typename A, typename T>
 struct unique_node : boost::unordered::detail::value_base<T>
@@ -3913,17 +3895,9 @@ struct table_impl : boost::unordered::detail::table<Types>
         }
     }
 };
-}
-}
-}
 
-namespace boost {
-namespace unordered {
-namespace detail {
-
-template <typename A, typename T> struct grouped_node;
-template <typename T> struct grouped_ptr_node;
-template <typename Types> struct grouped_table_impl;
+////////////////////////////////////////////////////////////////////////
+// Grouped nodes
 
 template <typename A, typename T>
 struct grouped_node : boost::unordered::detail::value_base<T>