diff --git a/doc/docca/example/include/docca/example.hpp b/doc/docca/example/include/docca/example.hpp
index daf1a475..f1591357 100644
--- a/doc/docca/example/include/docca/example.hpp
+++ b/doc/docca/example/include/docca/example.hpp
@@ -67,13 +67,19 @@ using t_type = std::vector<T>;
 
     Description
 */
-using vod = void_or_deduced;
+using vod = __deduced__;
+
+/** See below
+
+    Description
+*/
+using sb = __see_below__;
 
 /** Implementation-defined
 
     Description
 */
-using impdef = implementation_defined;
+using impdef = __implementation_defined__;
 
 /** Variable
 
diff --git a/doc/docca/include/docca/doxygen.xsl b/doc/docca/include/docca/doxygen.xsl
index dbd8ed1b..19e1fd3d 100644
--- a/doc/docca/include/docca/doxygen.xsl
+++ b/doc/docca/include/docca/doxygen.xsl
@@ -178,11 +178,17 @@
   </xsl:variable>
   <xsl:variable name="cleaned">
     <xsl:choose>
-      <xsl:when test="$type='implementation_defined'">
+      <xsl:when test="$type='__implementation_defined__'">
         <xsl:text>``['implementation-defined]``</xsl:text>
       </xsl:when>
+      <xsl:when test="$type='__see_below__'">
+        <xsl:text>``['see-below]``</xsl:text>
+      </xsl:when>
+      <xsl:when test="$type='__deduced__'">
+        <xsl:text>``__deduced__``</xsl:text>
+      </xsl:when>
       <xsl:when test="$type='void_or_deduced'">
-        <xsl:text>``__void_or_deduced__``</xsl:text>
+        <xsl:text>``__deduced__``</xsl:text>
       </xsl:when>
       <xsl:otherwise>
         <xsl:value-of select="$type"/>
diff --git a/include/boost/beast/core/bind_handler.hpp b/include/boost/beast/core/bind_handler.hpp
index 0fb7b823..1a1b3e40 100644
--- a/include/boost/beast/core/bind_handler.hpp
+++ b/include/boost/beast/core/bind_handler.hpp
@@ -54,7 +54,7 @@ namespace beast {
 */
 template<class Handler, class... Args>
 #if BOOST_BEAST_DOXYGEN
-implementation_defined
+__implementation_defined__
 #else
 detail::bound_handler<
     typename std::decay<Handler>::type, Args...>
diff --git a/include/boost/beast/core/buffered_read_stream.hpp b/include/boost/beast/core/buffered_read_stream.hpp
index 97406230..2c975b14 100644
--- a/include/boost/beast/core/buffered_read_stream.hpp
+++ b/include/boost/beast/core/buffered_read_stream.hpp
@@ -174,7 +174,7 @@ public:
         `NextLayer` has a member function named `get_executor`.
     */
 #if BOOST_BEAST_DOXYGEN
-    implementation_defined
+    __implementation_defined__
 #else
     template<
         class T = next_layer_type,
diff --git a/include/boost/beast/core/buffers_adapter.hpp b/include/boost/beast/core/buffers_adapter.hpp
index 2000ce24..a5451818 100644
--- a/include/boost/beast/core/buffers_adapter.hpp
+++ b/include/boost/beast/core/buffers_adapter.hpp
@@ -77,10 +77,10 @@ public:
 
 #if BOOST_BEAST_DOXYGEN
     /// The type used to represent the input sequence as a list of buffers.
-    using const_buffers_type = implementation_defined;
+    using const_buffers_type = __implementation_defined__;
 
     /// The type used to represent the output sequence as a list of buffers.
-    using mutable_buffers_type = implementation_defined;
+    using mutable_buffers_type = __implementation_defined__;
 
 #else
     class const_buffers_type;
diff --git a/include/boost/beast/core/buffers_cat.hpp b/include/boost/beast/core/buffers_cat.hpp
index 1d711b3b..cf9dd07c 100644
--- a/include/boost/beast/core/buffers_cat.hpp
+++ b/include/boost/beast/core/buffers_cat.hpp
@@ -34,7 +34,7 @@ public:
         Otherwise, `value_type` will be `boost::asio::const_buffer`.
     */
 #if BOOST_BEAST_DOXYGEN
-    using value_type = implementation_defined;
+    using value_type = __implementation_defined__;
 #else
     using value_type = typename
         detail::common_buffers_type<Buffers...>::type;
diff --git a/include/boost/beast/core/buffers_prefix.hpp b/include/boost/beast/core/buffers_prefix.hpp
index 175610f1..f606b309 100644
--- a/include/boost/beast/core/buffers_prefix.hpp
+++ b/include/boost/beast/core/buffers_prefix.hpp
@@ -66,7 +66,7 @@ public:
 
 #if BOOST_BEAST_DOXYGEN
     /// A bidirectional iterator type that may be used to read elements.
-    using const_iterator = implementation_defined;
+    using const_iterator = __implementation_defined__;
 
 #else
     class const_iterator;
diff --git a/include/boost/beast/core/buffers_suffix.hpp b/include/boost/beast/core/buffers_suffix.hpp
index 39596945..bbdf72f4 100644
--- a/include/boost/beast/core/buffers_suffix.hpp
+++ b/include/boost/beast/core/buffers_suffix.hpp
@@ -82,7 +82,7 @@ public:
         `boost::asio::const_buffer`.
     */
 #if BOOST_BEAST_DOXYGEN
-    using value_type = implementation_defined;
+    using value_type = __implementation_defined__;
 #else
     using value_type = typename std::conditional<
         std::is_convertible<typename
@@ -94,7 +94,7 @@ public:
 
 #if BOOST_BEAST_DOXYGEN
     /// A bidirectional iterator type that may be used to read elements.
-    using const_iterator = implementation_defined;
+    using const_iterator = __implementation_defined__;
 
 #else
     class const_iterator;
diff --git a/include/boost/beast/core/multi_buffer.hpp b/include/boost/beast/core/multi_buffer.hpp
index 046ed83a..27c43ac4 100644
--- a/include/boost/beast/core/multi_buffer.hpp
+++ b/include/boost/beast/core/multi_buffer.hpp
@@ -84,10 +84,10 @@ public:
 
 #if BOOST_BEAST_DOXYGEN
     /// The type used to represent the input sequence as a list of buffers.
-    using const_buffers_type = implementation_defined;
+    using const_buffers_type = __implementation_defined__;
 
     /// The type used to represent the output sequence as a list of buffers.
-    using mutable_buffers_type = implementation_defined;
+    using mutable_buffers_type = __implementation_defined__;
 
 #else
     class const_buffers_type;
diff --git a/include/boost/beast/core/ostream.hpp b/include/boost/beast/core/ostream.hpp
index 1f00289b..1196023d 100644
--- a/include/boost/beast/core/ostream.hpp
+++ b/include/boost/beast/core/ostream.hpp
@@ -43,7 +43,7 @@ namespace beast {
 */
 template<class ConstBufferSequence>
 #if BOOST_BEAST_DOXYGEN
-implementation_defined
+__implementation_defined__
 #else
 detail::buffers_helper<ConstBufferSequence>
 #endif
@@ -82,7 +82,7 @@ buffers(ConstBufferSequence const& b)
 */
 template<class DynamicBuffer>
 #if BOOST_BEAST_DOXYGEN
-implementation_defined
+__implementation_defined__
 #else
 detail::ostream_helper<
     DynamicBuffer, char, std::char_traits<char>,
diff --git a/include/boost/beast/http/basic_dynamic_body.hpp b/include/boost/beast/http/basic_dynamic_body.hpp
index ba7208b7..fcbba339 100644
--- a/include/boost/beast/http/basic_dynamic_body.hpp
+++ b/include/boost/beast/http/basic_dynamic_body.hpp
@@ -62,7 +62,7 @@ struct basic_dynamic_body
         Meets the requirements of @b BodyReader.
     */
 #if BOOST_BEAST_DOXYGEN
-    using reader = implementation_defined;
+    using reader = __implementation_defined__;
 #else
     class reader
     {
@@ -122,7 +122,7 @@ struct basic_dynamic_body
         Meets the requirements of @b BodyWriter.
     */
 #if BOOST_BEAST_DOXYGEN
-    using writer = implementation_defined;
+    using writer = __implementation_defined__;
 #else
     class writer
     {
diff --git a/include/boost/beast/http/buffer_body.hpp b/include/boost/beast/http/buffer_body.hpp
index bd420d9f..d6dba566 100644
--- a/include/boost/beast/http/buffer_body.hpp
+++ b/include/boost/beast/http/buffer_body.hpp
@@ -96,7 +96,7 @@ struct buffer_body
         Meets the requirements of @b BodyReader.
     */
 #if BOOST_BEAST_DOXYGEN
-    using reader = implementation_defined;
+    using reader = __implementation_defined__;
 #else
     class reader
     {
@@ -154,7 +154,7 @@ struct buffer_body
         Meets the requirements of @b BodyWriter.
     */
 #if BOOST_BEAST_DOXYGEN
-    using writer = implementation_defined;
+    using writer = __implementation_defined__;
 #else
     class writer
     {
diff --git a/include/boost/beast/http/chunk_encode.hpp b/include/boost/beast/http/chunk_encode.hpp
index 4994765f..c782b503 100644
--- a/include/boost/beast/http/chunk_encode.hpp
+++ b/include/boost/beast/http/chunk_encode.hpp
@@ -46,7 +46,7 @@ struct chunk_crlf
 
     /// Required for @b ConstBufferSequence
 #if BOOST_BEAST_DOXYGEN
-    using value_type = implementation_defined;
+    using value_type = __implementation_defined__;
 #else
     using value_type = detail::chunk_crlf_iter::value_type;
 #endif
@@ -229,14 +229,14 @@ public:
 
     /// Required for @b ConstBufferSequence
 #if BOOST_BEAST_DOXYGEN
-    using value_type = implementation_defined;
+    using value_type = __implementation_defined__;
 #else
     using value_type = typename view_type::value_type;
 #endif
 
     /// Required for @b ConstBufferSequence
 #if BOOST_BEAST_DOXYGEN
-    using const_iterator = implementation_defined;
+    using const_iterator = __implementation_defined__;
 #else
     using const_iterator = typename view_type::const_iterator;
 #endif
@@ -423,14 +423,14 @@ public:
 
     /// Required for @b ConstBufferSequence
 #if BOOST_BEAST_DOXYGEN
-    using value_type = implementation_defined;
+    using value_type = __implementation_defined__;
 #else
     using value_type = typename view_type::value_type;
 #endif
 
     /// Required for @b ConstBufferSequence
 #if BOOST_BEAST_DOXYGEN
-    using const_iterator = implementation_defined;
+    using const_iterator = __implementation_defined__;
 #else
     using const_iterator = typename view_type::const_iterator;
 #endif
@@ -528,7 +528,7 @@ public:
 
     /// Required for @b ConstBufferSequence
 #if BOOST_BEAST_DOXYGEN
-    using value_type = implementation_defined;
+    using value_type = __implementation_defined__;
 #else
     using value_type =
         typename view_type::value_type;
@@ -536,7 +536,7 @@ public:
 
     /// Required for @b ConstBufferSequence
 #if BOOST_BEAST_DOXYGEN
-    using const_iterator = implementation_defined;
+    using const_iterator = __implementation_defined__;
 #else
     using const_iterator =
         typename view_type::const_iterator;
diff --git a/include/boost/beast/http/detail/basic_parsed_list.hpp b/include/boost/beast/http/detail/basic_parsed_list.hpp
index 5577fba7..2198c978 100644
--- a/include/boost/beast/http/detail/basic_parsed_list.hpp
+++ b/include/boost/beast/http/detail/basic_parsed_list.hpp
@@ -36,7 +36,7 @@ public:
 
     /// A constant iterator to a list element.
 #if BOOST_BEAST_DOXYGEN
-    using const_iterator = implementation_defined;
+    using const_iterator = __implementation_defined__;
 #else
     class const_iterator;
 #endif
diff --git a/include/boost/beast/http/empty_body.hpp b/include/boost/beast/http/empty_body.hpp
index d56c14b4..c5dd9c55 100644
--- a/include/boost/beast/http/empty_body.hpp
+++ b/include/boost/beast/http/empty_body.hpp
@@ -57,7 +57,7 @@ struct empty_body
         Meets the requirements of @b BodyReader.
     */
 #if BOOST_BEAST_DOXYGEN
-    using reader = implementation_defined;
+    using reader = __implementation_defined__;
 #else
     struct reader
     {
@@ -95,7 +95,7 @@ struct empty_body
         Meets the requirements of @b BodyWriter.
     */
 #if BOOST_BEAST_DOXYGEN
-    using writer = implementation_defined;
+    using writer = __implementation_defined__;
 #else
     struct writer
     {
diff --git a/include/boost/beast/http/fields.hpp b/include/boost/beast/http/fields.hpp
index 8d526867..caa03d1c 100644
--- a/include/boost/beast/http/fields.hpp
+++ b/include/boost/beast/http/fields.hpp
@@ -117,7 +117,7 @@ public:
         The case-comparison operation is defined only for low-ASCII characters.
     */
 #if BOOST_BEAST_DOXYGEN
-    using key_compare = implementation_defined;
+    using key_compare = __implementation_defined__;
 #else
     struct key_compare : beast::iless
 #endif
@@ -164,7 +164,7 @@ public:
 
     /// The algorithm used to serialize the header
 #if BOOST_BEAST_DOXYGEN
-    using writer = implementation_defined;
+    using writer = __implementation_defined__;
 #else
     class writer;
 #endif
@@ -277,7 +277,7 @@ public:
 public:
     /// A constant iterator to the field sequence.
 #if BOOST_BEAST_DOXYGEN
-    using const_iterator = implementation_defined;
+    using const_iterator = __implementation_defined__;
 #else
     using const_iterator = typename list_t::const_iterator;
 #endif
diff --git a/include/boost/beast/http/rfc7230.hpp b/include/boost/beast/http/rfc7230.hpp
index 952cb929..3ece197b 100644
--- a/include/boost/beast/http/rfc7230.hpp
+++ b/include/boost/beast/http/rfc7230.hpp
@@ -66,7 +66,7 @@ public:
 
     /// A constant iterator to the list
 #if BOOST_BEAST_DOXYGEN
-    using const_iterator = implementation_defined;
+    using const_iterator = __implementation_defined__;
 #else
     class const_iterator;
 #endif
@@ -155,7 +155,7 @@ public:
 
     /// A constant iterator to the list
 #if BOOST_BEAST_DOXYGEN
-    using const_iterator = implementation_defined;
+    using const_iterator = __implementation_defined__;
 #else
     class const_iterator;
 #endif
@@ -243,7 +243,7 @@ public:
 
     /// A constant iterator to the list
 #if BOOST_BEAST_DOXYGEN
-    using const_iterator = implementation_defined;
+    using const_iterator = __implementation_defined__;
 #else
     class const_iterator;
 #endif
diff --git a/include/boost/beast/http/serializer.hpp b/include/boost/beast/http/serializer.hpp
index 352e735f..6ccfab8a 100644
--- a/include/boost/beast/http/serializer.hpp
+++ b/include/boost/beast/http/serializer.hpp
@@ -69,7 +69,7 @@ public:
         implementation of the corresponding @b BodyWriter.
     */
 #if BOOST_BEAST_DOXYGEN
-    using value_type = implementation_defined;
+    using value_type = __implementation_defined__;
 #else
     using value_type = typename std::conditional<
         std::is_constructible<typename Body::writer,
diff --git a/include/boost/beast/http/span_body.hpp b/include/boost/beast/http/span_body.hpp
index f2048116..3926e81a 100644
--- a/include/boost/beast/http/span_body.hpp
+++ b/include/boost/beast/http/span_body.hpp
@@ -64,7 +64,7 @@ public:
         Meets the requirements of @b BodyReader.
     */
 #if BOOST_BEAST_DOXYGEN
-    using reader = implementation_defined;
+    using reader = __implementation_defined__;
 #else
     class reader
     {
@@ -125,7 +125,7 @@ public:
         Meets the requirements of @b BodyWriter.
     */
 #if BOOST_BEAST_DOXYGEN
-    using writer = implementation_defined;
+    using writer = __implementation_defined__;
 #else
     class writer
     {
diff --git a/include/boost/beast/http/string_body.hpp b/include/boost/beast/http/string_body.hpp
index 1e37aa0d..2b4e1b43 100644
--- a/include/boost/beast/http/string_body.hpp
+++ b/include/boost/beast/http/string_body.hpp
@@ -72,7 +72,7 @@ public:
         Meets the requirements of @b BodyReader.
     */
 #if BOOST_BEAST_DOXYGEN
-    using reader = implementation_defined;
+    using reader = __implementation_defined__;
 #else
     class reader
     {
@@ -153,7 +153,7 @@ public:
         Meets the requirements of @b BodyWriter.
     */
 #if BOOST_BEAST_DOXYGEN
-    using writer = implementation_defined;
+    using writer = __implementation_defined__;
 #else
     class writer
     {
diff --git a/include/boost/beast/http/vector_body.hpp b/include/boost/beast/http/vector_body.hpp
index 40c885e4..62d866f0 100644
--- a/include/boost/beast/http/vector_body.hpp
+++ b/include/boost/beast/http/vector_body.hpp
@@ -67,7 +67,7 @@ public:
         Meets the requirements of @b BodyReader.
     */
 #if BOOST_BEAST_DOXYGEN
-    using reader = implementation_defined;
+    using reader = __implementation_defined__;
 #else
     class reader
     {
@@ -142,7 +142,7 @@ public:
         Meets the requirements of @b BodyWriter.
     */
 #if BOOST_BEAST_DOXYGEN
-    using writer = implementation_defined;
+    using writer = __implementation_defined__;
 #else
     class writer
     {