diff --git a/coord/traits.hpp b/coord/traits.hpp
index 2619bbd3..0d80cf2e 100644
--- a/coord/traits.hpp
+++ b/coord/traits.hpp
@@ -3,11 +3,10 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  *
- * Copyright 2012-2017 Danny Robson <danny@nerdcruft.net>
+ * Copyright 2012-2019 Danny Robson <danny@nerdcruft.net>
  */
 
-#ifndef CRUFT_UTIL_COORD_TRAITS_HPP
-#define CRUFT_UTIL_COORD_TRAITS_HPP
+#pragma once
 
 #include "fwd.hpp"
 
@@ -197,12 +196,14 @@ namespace cruft {
     template <typename,typename=void> struct arity {};
 
 
+    //-------------------------------------------------------------------------
     template <typename T>
     struct arity<T,std::enable_if_t<std::is_arithmetic_v<T>,void>
     > :std::integral_constant<std::size_t, 1>
     { };
 
 
+    //-------------------------------------------------------------------------
     template <typename T>
     struct arity<
         T,std::enable_if_t<is_coord_v<T>,void>
@@ -210,9 +211,46 @@ namespace cruft {
     { };
 
 
-    ///////////////////////////////////////////////////////////////////////////
+    //-------------------------------------------------------------------------
     template <typename T>
     constexpr auto arity_v = arity<T>::value;
+
+
+    ///////////////////////////////////////////////////////////////////////////
+    template <typename, typename = void> struct value_trait {};
+
+
+    //-------------------------------------------------------------------------
+    template <size_t S, typename T>
+    struct value_trait<cruft::point<S,T>>
+    { using value_type = T; };
+
+
+    //-------------------------------------------------------------------------
+    template <typename OuterT>
+    using value_trait_t = typename value_trait<OuterT>::value_type;
 }
 
-#endif
+
+#include "../types/description.hpp"
+
+namespace cruft::types {
+    template <typename CoordT>
+    struct arity_trait<
+        CoordT,
+        std::enable_if_t<
+            ::cruft::is_coord_v<CoordT>
+        >
+    > : public ::cruft::arity<CoordT> { };
+
+
+    template <typename CoordT>
+    struct category_traits<
+        CoordT,
+        std::enable_if_t<
+        ::cruft::is_coord_v<CoordT>
+        >
+    > : public category_traits<
+        ::cruft::value_trait_t<CoordT>
+    > { };
+}
diff --git a/strongdef.hpp b/strongdef.hpp
index 17db6329..e3eb2ace 100644
--- a/strongdef.hpp
+++ b/strongdef.hpp
@@ -130,3 +130,22 @@ static auto indices (ContainerT const &obj)
 
     return view {obj};
 }
+
+
+#include "types/description.hpp"
+namespace cruft::types {
+    template <typename TagT, typename ValueT>
+    struct arity_trait<
+        ::cruft::strongdef::index<TagT, ValueT>
+    > :
+        arity_trait<ValueT>
+    { ; };
+
+
+    template <typename TagT, typename ValueT>
+    struct category_traits<
+        ::cruft::strongdef::index<TagT,ValueT>
+    > :
+        public category_traits<ValueT>
+    {};
+}
diff --git a/types/description.hpp b/types/description.hpp
index f925d9eb..7292332d 100644
--- a/types/description.hpp
+++ b/types/description.hpp
@@ -10,7 +10,7 @@
 
 #include "../std.hpp"
 #include "../types.hpp"
-#include "../debug.hpp"
+#include "../debug/panic.hpp"
 
 #include <cstddef>
 #include <type_traits>
@@ -43,6 +43,17 @@ namespace cruft::types {
     > { };
 
 
+    //-------------------------------------------------------------------------
+    // Punt the handling of any enum to the underlying type.
+    template <typename EnumT>
+    struct arity_trait<
+        EnumT,
+        std::enable_if_t<std::is_enum_v<EnumT>>
+    > : public arity_trait<
+        std::underlying_type_t<EnumT>
+    > { };
+
+
     //-------------------------------------------------------------------------
     template <typename T>
     constexpr auto arity_v = arity_trait<T>::value;
@@ -99,7 +110,7 @@ namespace cruft::types {
 
 
     //-------------------------------------------------------------------------
-    template <typename T>
+    template <typename T, typename = void>
     struct category_traits;
 
     template <> struct category_traits<u08> : public std::integral_constant<category,category::UNSIGNED> {};
@@ -117,6 +128,17 @@ namespace cruft::types {
 
     template <> struct category_traits<bool> : public std::integral_constant<category,category::BOOL> {};
 
+
+    template <typename EnumT>
+    struct category_traits<
+        EnumT,
+        std::enable_if_t<
+            std::is_enum_v<EnumT>
+        >
+    > : public category_traits<std::underlying_type_t<EnumT>>
+    { };
+
+
     template <typename T>
     constexpr auto category_traits_v = category_traits<T>::value;