diff --git a/include/boost/system/detail/error_condition.hpp b/include/boost/system/detail/error_condition.hpp
new file mode 100644
index 0000000..5d6840f
--- /dev/null
+++ b/include/boost/system/detail/error_condition.hpp
@@ -0,0 +1,159 @@
+#ifndef BOOST_SYSTEM_DETAIL_ERROR_CONDITION_HPP_INCLUDED
+#define BOOST_SYSTEM_DETAIL_ERROR_CONDITION_HPP_INCLUDED
+
+//  Copyright Beman Dawes 2006, 2007
+//  Copyright Christoper Kohlhoff 2007
+//  Copyright Peter Dimov 2017, 2018
+//
+//  Distributed under the Boost Software License, Version 1.0. (See accompanying
+//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+//  See library home page at http://www.boost.org/libs/system
+
+#include <boost/system/detail/error_category.hpp>
+#include <boost/system/detail/generic_category.hpp>
+#include <boost/system/detail/enable_if.hpp>
+#include <boost/system/is_error_condition_enum.hpp>
+
+namespace boost
+{
+
+namespace system
+{
+
+// class error_condition
+
+// error_conditions are portable, error_codes are system or library specific
+
+class error_condition
+{
+private:
+
+    int val_;
+    bool failed_;
+    error_category const * cat_;
+
+public:
+
+    // constructors:
+
+    BOOST_SYSTEM_CONSTEXPR error_condition() BOOST_NOEXCEPT:
+        val_( 0 ), failed_( false ), cat_( &generic_category() )
+    {
+    }
+
+    BOOST_SYSTEM_CONSTEXPR error_condition( int val, const error_category & cat ) BOOST_NOEXCEPT:
+        val_( val ), failed_( detail::failed_impl( val, cat ) ), cat_( &cat )
+    {
+    }
+
+    template<class ErrorConditionEnum> BOOST_SYSTEM_CONSTEXPR error_condition( ErrorConditionEnum e,
+        typename detail::enable_if<is_error_condition_enum<ErrorConditionEnum>::value>::type* = 0) BOOST_NOEXCEPT
+    {
+        *this = make_error_condition( e );
+    }
+
+    // modifiers:
+
+    BOOST_SYSTEM_CONSTEXPR void assign( int val, const error_category & cat ) BOOST_NOEXCEPT
+    {
+        val_ = val;
+        failed_ = detail::failed_impl( val, cat );
+        cat_ = &cat;
+    }
+
+    template<typename ErrorConditionEnum>
+        BOOST_SYSTEM_CONSTEXPR typename detail::enable_if<is_error_condition_enum<ErrorConditionEnum>::value, error_condition>::type &
+        operator=( ErrorConditionEnum val ) BOOST_NOEXCEPT
+    {
+        *this = make_error_condition( val );
+        return *this;
+    }
+
+    BOOST_SYSTEM_CONSTEXPR void clear() BOOST_NOEXCEPT
+    {
+        val_ = 0;
+        failed_ = false;
+        cat_ = &generic_category();
+    }
+
+    // observers:
+
+    BOOST_SYSTEM_CONSTEXPR int value() const BOOST_NOEXCEPT
+    {
+        return val_;
+    }
+
+    BOOST_SYSTEM_CONSTEXPR const error_category & category() const BOOST_NOEXCEPT
+    {
+        return *cat_;
+    }
+
+    std::string message() const
+    {
+        return cat_->message( value() );
+    }
+
+    char const * message( char * buffer, std::size_t len ) const BOOST_NOEXCEPT
+    {
+        return cat_->message( value(), buffer, len );
+    }
+
+    BOOST_SYSTEM_CONSTEXPR bool failed() const BOOST_NOEXCEPT
+    {
+        return failed_;
+    }
+
+#if !defined(BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS)
+
+    BOOST_SYSTEM_CONSTEXPR explicit operator bool() const BOOST_NOEXCEPT  // true if error
+    {
+        return failed_;
+    }
+
+#else
+
+    typedef void (*unspecified_bool_type)();
+    static void unspecified_bool_true() {}
+
+    BOOST_SYSTEM_CONSTEXPR operator unspecified_bool_type() const BOOST_NOEXCEPT  // true if error
+    {
+        return failed_? unspecified_bool_true: 0;
+    }
+
+    BOOST_SYSTEM_CONSTEXPR bool operator!() const BOOST_NOEXCEPT  // true if no error
+    {
+        return !failed_;
+    }
+
+#endif
+
+    // relationals:
+    //  the more symmetrical non-member syntax allows enum
+    //  conversions work for both rhs and lhs.
+
+    BOOST_SYSTEM_CONSTEXPR inline friend bool operator==( const error_condition & lhs, const error_condition & rhs ) BOOST_NOEXCEPT
+    {
+        return lhs.val_ == rhs.val_ && *lhs.cat_ == *rhs.cat_;
+    }
+
+    BOOST_SYSTEM_CONSTEXPR inline friend bool operator<( const error_condition & lhs, const error_condition & rhs ) BOOST_NOEXCEPT
+    {
+        return *lhs.cat_ < *rhs.cat_ || ( *lhs.cat_ == *rhs.cat_ && lhs.val_ < rhs.val_ );
+    }
+
+#if defined(BOOST_SYSTEM_HAS_SYSTEM_ERROR)
+
+    operator std::error_condition () const
+    {
+        return std::error_condition( value(), category() );
+    }
+
+#endif
+};
+
+} // namespace system
+
+} // namespace boost
+
+#endif // #ifndef BOOST_SYSTEM_DETAIL_ERROR_CONDITION_HPP_INCLUDED
diff --git a/include/boost/system/detail/generic_category.hpp b/include/boost/system/detail/generic_category.hpp
index 01f5687..bad6085 100644
--- a/include/boost/system/detail/generic_category.hpp
+++ b/include/boost/system/detail/generic_category.hpp
@@ -134,6 +134,55 @@ inline char const * generic_error_category::message( int ev, char * buffer, std:
 
 } // namespace detail
 
+// generic_category()
+
+#if defined(BOOST_SYSTEM_HAS_CONSTEXPR)
+
+namespace detail
+{
+
+template<class T> struct BOOST_SYMBOL_VISIBLE generic_cat_holder
+{
+    static constexpr generic_error_category instance{};
+};
+
+// Before C++17 it was mandatory to redeclare all static constexpr
+#if defined(BOOST_NO_CXX17_INLINE_VARIABLES)
+template<class T> constexpr generic_error_category generic_cat_holder<T>::instance;
+#endif
+
+} // namespace detail
+
+constexpr error_category const & generic_category() BOOST_NOEXCEPT
+{
+    return detail::generic_cat_holder<void>::instance;
+}
+
+#else // #if defined(BOOST_SYSTEM_HAS_CONSTEXPR)
+
+#if !defined(__SUNPRO_CC) // trailing __global is not supported
+inline error_category const & generic_category() BOOST_NOEXCEPT BOOST_SYMBOL_VISIBLE;
+#endif
+
+inline error_category const & generic_category() BOOST_NOEXCEPT
+{
+    static const detail::generic_error_category instance;
+    return instance;
+}
+
+#endif // #if defined(BOOST_SYSTEM_HAS_CONSTEXPR)
+
+// deprecated synonyms
+
+#ifdef BOOST_SYSTEM_ENABLE_DEPRECATED
+
+inline const error_category & get_generic_category() { return generic_category(); }
+inline const error_category & get_posix_category() { return generic_category(); }
+static const error_category & posix_category BOOST_ATTRIBUTE_UNUSED = generic_category();
+static const error_category & errno_ecat BOOST_ATTRIBUTE_UNUSED = generic_category();
+
+#endif
+
 } // namespace system
 
 } // namespace boost
diff --git a/include/boost/system/detail/system_category.hpp b/include/boost/system/detail/system_category.hpp
index 8e9d69b..633989b 100644
--- a/include/boost/system/detail/system_category.hpp
+++ b/include/boost/system/detail/system_category.hpp
@@ -58,6 +58,53 @@ public:
 
 } // namespace detail
 
+// system_category()
+
+#if defined(BOOST_SYSTEM_HAS_CONSTEXPR)
+
+namespace detail
+{
+
+template<class T> struct BOOST_SYMBOL_VISIBLE system_cat_holder
+{
+    static constexpr system_error_category instance{};
+};
+
+// Before C++17 it was mandatory to redeclare all static constexpr
+#if defined(BOOST_NO_CXX17_INLINE_VARIABLES)
+template<class T> constexpr system_error_category system_cat_holder<T>::instance;
+#endif
+
+} // namespace detail
+
+constexpr error_category const & system_category() BOOST_NOEXCEPT
+{
+    return detail::system_cat_holder<void>::instance;
+}
+
+#else // #if defined(BOOST_SYSTEM_HAS_CONSTEXPR)
+
+#if !defined(__SUNPRO_CC) // trailing __global is not supported
+inline error_category const & system_category() BOOST_NOEXCEPT BOOST_SYMBOL_VISIBLE;
+#endif
+
+inline error_category const & system_category() BOOST_NOEXCEPT
+{
+    static const detail::system_error_category instance;
+    return instance;
+}
+
+#endif // #if defined(BOOST_SYSTEM_HAS_CONSTEXPR)
+
+// deprecated synonyms
+
+#ifdef BOOST_SYSTEM_ENABLE_DEPRECATED
+
+inline const error_category & get_system_category() { return system_category(); }
+static const error_category & native_ecat BOOST_ATTRIBUTE_UNUSED = system_category();
+
+#endif
+
 } // namespace system
 
 } // namespace boost
diff --git a/include/boost/system/error_code.hpp b/include/boost/system/error_code.hpp
index 7e92edc..ad4b3cd 100644
--- a/include/boost/system/error_code.hpp
+++ b/include/boost/system/error_code.hpp
@@ -17,6 +17,7 @@
 #include <boost/system/detail/generic_category.hpp>
 #include <boost/system/detail/system_category.hpp>
 #include <boost/system/detail/enable_if.hpp>
+#include <boost/system/detail/error_condition.hpp>
 #include <boost/system/api_config.hpp>
 #include <boost/system/detail/config.hpp>
 #include <boost/cstdint.hpp>
@@ -44,202 +45,6 @@ class error_code;         // values defined by the operating system
 class error_condition;    // portable generic values defined below, but ultimately
                           // based on the POSIX standard
 
-// generic_category(), system_category()
-
-#if defined(BOOST_SYSTEM_HAS_CONSTEXPR)
-
-namespace detail
-{
-
-template<class T> struct BOOST_SYMBOL_VISIBLE cat_holder
-{
-    static constexpr system_error_category system_category_instance{};
-    static constexpr generic_error_category generic_category_instance{};
-};
-
-// Before C++17 it was mandatory to redeclare all static constexpr
-#if defined(BOOST_NO_CXX17_INLINE_VARIABLES)
-template<class T> constexpr system_error_category cat_holder<T>::system_category_instance;
-template<class T> constexpr generic_error_category cat_holder<T>::generic_category_instance;
-#endif
-
-} // namespace detail
-
-constexpr error_category const & system_category() BOOST_NOEXCEPT
-{
-    return detail::cat_holder<void>::system_category_instance;
-}
-
-constexpr error_category const & generic_category() BOOST_NOEXCEPT
-{
-    return detail::cat_holder<void>::generic_category_instance;
-}
-
-#else // #if defined(BOOST_SYSTEM_HAS_CONSTEXPR)
-
-#if !defined(__SUNPRO_CC) // trailing __global is not supported
-inline error_category const & system_category() BOOST_NOEXCEPT BOOST_SYMBOL_VISIBLE;
-inline error_category const & generic_category() BOOST_NOEXCEPT BOOST_SYMBOL_VISIBLE;
-#endif
-
-inline error_category const & system_category() BOOST_NOEXCEPT
-{
-    static const detail::system_error_category system_category_instance;
-    return system_category_instance;
-}
-
-inline error_category const & generic_category() BOOST_NOEXCEPT
-{
-    static const detail::generic_error_category generic_category_instance;
-    return generic_category_instance;
-}
-
-#endif // #if defined(BOOST_SYSTEM_HAS_CONSTEXPR)
-
-// deprecated synonyms
-
-#ifdef BOOST_SYSTEM_ENABLE_DEPRECATED
-
-inline const error_category & get_system_category() { return system_category(); }
-inline const error_category & get_generic_category() { return generic_category(); }
-inline const error_category & get_posix_category() { return generic_category(); }
-static const error_category & posix_category BOOST_ATTRIBUTE_UNUSED = generic_category();
-static const error_category & errno_ecat BOOST_ATTRIBUTE_UNUSED = generic_category();
-static const error_category & native_ecat BOOST_ATTRIBUTE_UNUSED = system_category();
-
-#endif
-
-// class error_condition
-
-// error_conditions are portable, error_codes are system or library specific
-
-class error_condition
-{
-private:
-
-    int val_;
-    bool failed_;
-    error_category const * cat_;
-
-public:
-
-    // constructors:
-
-    BOOST_SYSTEM_CONSTEXPR error_condition() BOOST_NOEXCEPT:
-        val_( 0 ), failed_( false ), cat_( &generic_category() )
-    {
-    }
-
-    BOOST_SYSTEM_CONSTEXPR error_condition( int val, const error_category & cat ) BOOST_NOEXCEPT:
-        val_( val ), failed_( detail::failed_impl( val, cat ) ), cat_( &cat )
-    {
-    }
-
-    template<class ErrorConditionEnum> BOOST_SYSTEM_CONSTEXPR error_condition( ErrorConditionEnum e,
-        typename detail::enable_if<is_error_condition_enum<ErrorConditionEnum>::value>::type* = 0) BOOST_NOEXCEPT
-    {
-        *this = make_error_condition( e );
-    }
-
-    // modifiers:
-
-    BOOST_SYSTEM_CONSTEXPR void assign( int val, const error_category & cat ) BOOST_NOEXCEPT
-    {
-        val_ = val;
-        failed_ = detail::failed_impl( val, cat );
-        cat_ = &cat;
-    }
-
-    template<typename ErrorConditionEnum>
-        BOOST_SYSTEM_CONSTEXPR typename detail::enable_if<is_error_condition_enum<ErrorConditionEnum>::value, error_condition>::type &
-        operator=( ErrorConditionEnum val ) BOOST_NOEXCEPT
-    {
-        *this = make_error_condition( val );
-        return *this;
-    }
-
-    BOOST_SYSTEM_CONSTEXPR void clear() BOOST_NOEXCEPT
-    {
-        val_ = 0;
-        failed_ = false;
-        cat_ = &generic_category();
-    }
-
-    // observers:
-
-    BOOST_SYSTEM_CONSTEXPR int value() const BOOST_NOEXCEPT
-    {
-        return val_;
-    }
-
-    BOOST_SYSTEM_CONSTEXPR const error_category & category() const BOOST_NOEXCEPT
-    {
-        return *cat_;
-    }
-
-    std::string message() const
-    {
-        return cat_->message( value() );
-    }
-
-    char const * message( char * buffer, std::size_t len ) const BOOST_NOEXCEPT
-    {
-        return cat_->message( value(), buffer, len );
-    }
-
-    BOOST_SYSTEM_CONSTEXPR bool failed() const BOOST_NOEXCEPT
-    {
-        return failed_;
-    }
-
-#if !defined(BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS)
-
-    BOOST_SYSTEM_CONSTEXPR explicit operator bool() const BOOST_NOEXCEPT  // true if error
-    {
-        return failed_;
-    }
-
-#else
-
-    typedef void (*unspecified_bool_type)();
-    static void unspecified_bool_true() {}
-
-    BOOST_SYSTEM_CONSTEXPR operator unspecified_bool_type() const BOOST_NOEXCEPT  // true if error
-    {
-        return failed_? unspecified_bool_true: 0;
-    }
-
-    BOOST_SYSTEM_CONSTEXPR bool operator!() const BOOST_NOEXCEPT  // true if no error
-    {
-        return !failed_;
-    }
-
-#endif
-
-    // relationals:
-    //  the more symmetrical non-member syntax allows enum
-    //  conversions work for both rhs and lhs.
-
-    BOOST_SYSTEM_CONSTEXPR inline friend bool operator==( const error_condition & lhs, const error_condition & rhs ) BOOST_NOEXCEPT
-    {
-        return lhs.val_ == rhs.val_ && *lhs.cat_ == *rhs.cat_;
-    }
-
-    BOOST_SYSTEM_CONSTEXPR inline friend bool operator<( const error_condition & lhs, const error_condition & rhs ) BOOST_NOEXCEPT
-    {
-        return *lhs.cat_ < *rhs.cat_ || ( *lhs.cat_ == *rhs.cat_ && lhs.val_ < rhs.val_ );
-    }
-
-#if defined(BOOST_SYSTEM_HAS_SYSTEM_ERROR)
-
-    operator std::error_condition () const
-    {
-        return std::error_condition( value(), category() );
-    }
-
-#endif
-};
-
 //  class error_code
 
 //  We want error_code to be a value type that can be copied without slicing