diff --git a/boost/yap/expression_fwd.hpp b/boost/yap/expression_fwd.hpp
index 2d7f2ca..a5cd44a 100644
--- a/boost/yap/expression_fwd.hpp
+++ b/boost/yap/expression_fwd.hpp
@@ -69,15 +69,25 @@ namespace boost { namespace yap {
         call ///< \c ()
     };
 
+#ifndef BOOST_YAP_DOXYGEN
+
     template <expr_kind Kind, typename Tuple>
     struct expression;
 
+#ifndef BOOST_YAP_DOXYGEN
+
+    /** A convenience alias for a terminal expression holding a \a T,
+        instantiated from expression template \a expr_template. */
     template <typename T, template <expr_kind, class> class expr_template = expression>
     using terminal = expr_template<expr_kind::terminal, hana::tuple<T>>;
 
+    /** A convenience alias for a reference expression holding an expression
+        \a T, instantiated from expression template \a expr_template. */
     template <typename T, template <expr_kind, class> class expr_template = expression>
     using expression_ref = expr_template<expr_kind::expr_ref, hana::tuple<std::remove_reference_t<T> *>>;
 
+#endif // BOOST_YAP_DOXYGEN
+
     template <typename Expr, typename ...T>
     decltype(auto) evaluate (Expr && expr, T && ...t);
 
@@ -99,8 +109,11 @@ namespace boost { namespace yap {
     template <typename Expr>
     decltype(auto) right (Expr && expr);
 
+#endif // BOOST_YAP_DOXYGEN
+
     namespace literals {
 
+        /** Creates literal placeholders.  Placeholder indices are 1-based. */
         template <char ...c>
         constexpr auto operator"" _p ()
         {
@@ -111,6 +124,8 @@ namespace boost { namespace yap {
 
     }
 
+#ifndef BOOST_YAP_DOXYGEN
+
     // Tag types -- one per expr_kind:
 
     struct expr_ref_tag {};
@@ -170,6 +185,8 @@ namespace boost { namespace yap {
     // n-ary
     struct call_tag {}; // ()
 
+#endif // BOOST_YAP_DOXYGEN
+
 } }
 
 #endif
diff --git a/boost/yap/print.hpp b/boost/yap/print.hpp
index c493d29..3b9ba34 100644
--- a/boost/yap/print.hpp
+++ b/boost/yap/print.hpp
@@ -119,6 +119,7 @@ namespace boost { namespace yap {
 
     }
 
+    /** Prints expression \a expr to stream \a os.  Returns \a os. */
     template <typename Expr>
     std::ostream & print (std::ostream & os, Expr const & expr)
     { return detail::print_impl(os, expr, 0, "    "); }