diff --git a/src/gmser_dyn_types.erl b/src/gmser_dyn_types.erl
new file mode 100644
index 0000000..cec7a30
--- /dev/null
+++ b/src/gmser_dyn_types.erl
@@ -0,0 +1,48 @@
+-module(gmser_dyn_types).
+
+-export([ from_list/2 ]).
+-export([ next_code/1 ]).
+
+next_code(#{codes := Codes}) ->
+    lists:max(maps:keys(Codes)) + 1.
+
+add_type(Tag, Code, Template, Types) ->
+    elem_to_type({Tag, Code, Template}, Types).
+
+from_list(L, Types) ->
+    lists:foldl(fun elem_to_type/2, Types, L).
+
+elem_to_type({Tag, Code, Template}, Acc) when is_atom(Tag), is_integer(Code) ->
+    #{codes := Codes, rev := Rev, templates := Temps} = Acc,
+    case {is_map_key(Tag, Rev), is_map_key(Code, Codes)} of
+        {false, false} ->
+            Acc#{ codes := Codes#{Code => Tag}
+                , rev := Rev#{Tag => Code}
+                , templates => Temps#{Tag => Template}
+                };
+        {true, _} -> error({duplicate_tag, Tag});
+        {_, true} -> error({duplicate_code, Code})
+    end;
+elem_to_type({modify, {Tag, Template}}, Acc) ->
+    #{codes := _, rev := Rev, templates := Templates} = Acc,
+    _ = maps:get(Tag, Rev),
+    Templates1 = Templates#{Tag := Template},
+    Acc#{templates := Templates1};
+elem_to_type({labels, Lbls}, Acc) ->
+    lists:foldl(fun add_label/2, Acc, Lbls);
+elem_to_type({vsn, V}, Acc) ->
+    Acc#{vsn => V};
+elem_to_type(Elem, _) ->
+    error({invalid_type, Elem}).
+
+add_label({L, Code}, #{labels := Lbls, rev_labels := RevLbls} = Acc)
+  when is_atom(L), is_integer(Code), Code > 0 ->
+    case {is_map_key(L, Lbls), is_map_key(Code, RevLbls)} of
+        {false, false} ->
+            Acc#{labels := Lbls#{L => Code},
+                 rev_labels := RevLbls#{Code => L}};
+        {true, _} -> error({duplicate_label, L});
+        {_, true} -> error({duplicate_label_code, Code})
+    end;
+add_label(Elem, _) ->
+    error({invalid_label, Elem}).