diff --git a/ds_generator.anubis b/ds_generator.anubis
index f891719..57fd1ba 100644
--- a/ds_generator.anubis
+++ b/ds_generator.anubis
@@ -12,7 +12,7 @@ transmit types/densaku.anubis
 
 public type DS_Generator_API:
   ds_api(
-    ((List(DS_Type), List(DS_Message), String) -> Maybe(One)) generate_type_files).
+    ((List(DS_Type_File), List(DS_Message), String) -> Maybe(One)) generate_type_files).
     
 public define Maybe(DS_Generator_API)
   load_ds_generator
diff --git a/types/ds_types.anubis b/types/ds_types.anubis
index 6890c56..d5a022f 100644
--- a/types/ds_types.anubis
+++ b/types/ds_types.anubis
@@ -125,16 +125,57 @@ public define DS_Type
   )=
   ds_type(type_name, message, ds_alts)
 .
+
+public type DS_Type_File_Output_Dir:
+  auto,                             //auto generated by densaku to given dir (in argument) + /types/generated/
+  relative_path(String rel_path),   //given dir (in argument) + path
+  absolute_path(String abs_path)    //abs_path 
+.
+
+public type DS_Type_File_Output_Name:
+  auto,                             //auto generated by densaku name of the type
+  name(String name)                 
+.
+  
+public type DS_Type_File:
+  ds_type_file (
+    DS_Type_File_Output_Dir   output_path,
+    DS_Type_File_Output_Name  file_name,
+    List(DS_Type)             types
+  )
+.
   
 public type Extern_type:
   extern(String type_name, String ext_read)
 .
 
+define Bool
+/* check if type_name is in the list beside_type.
+ * if yes return true and means the type is defined in same file
+ */
+  is_exists
+  (
+    String        type_name,
+    List(DS_Type) beside_type
+  )=
+  if beside_type is
+  {
+    []      then false,
+    [h . t] then
+      since h is ds_type(name, _, _),
+        if type_name = name then
+          true
+        else
+          is_exists(type_name, t)
+  }
+.
+
 define List(Extern_type)
   extract_extern_type
   (
     List(DS_Component)  components,
-    List(Extern_type)   so_far
+    List(Extern_type)   so_far,
+    List(DS_Type)       beside_type
   )=
   if components is
   {
@@ -142,13 +183,16 @@ define List(Extern_type)
     [h . t] then 
       since h is component(_b_list, _anb_type, _name, _comment),
       if _anb_type is ds_type(_type_name) then
-        extract_extern_type(
-          t, append_once(so_far, extern(_type_name, "types/generated/"+to_lower(_type_name)+".anubis")))
+        if is_exists(_type_name, beside_type) then
+          extract_extern_type(t, so_far, beside_type)
+        else
+          extract_extern_type(
+            t, append_once(so_far, extern(_type_name, "types/generated/"+to_lower(_type_name)+".anubis")), beside_type)
       else if _anb_type is extern_type(_type_name, read_file) then
         extract_extern_type(
-          t, append_once(so_far, extern(_type_name, read_file)))
+          t, append_once(so_far, extern(_type_name, read_file)), beside_type)
       else
-        extract_extern_type(t, so_far)
+        extract_extern_type(t, so_far, beside_type)
   }
 .
 
@@ -156,7 +200,8 @@ define List(Extern_type)
   extract_extern_type
   (
     List(DS_Alternative)  alt,
-    List(Extern_type)     so_far
+    List(Extern_type)     so_far,
+    List(DS_Type)         beside_type
   )=
   if alt is
   {
@@ -164,9 +209,9 @@ define List(Extern_type)
     [h . t] then  
       if h is
       {
-        enum(_ , _)                   then  extract_extern_type(t, so_far)
+        enum(_ , _)                   then  extract_extern_type(t, so_far, beside_type)
         alternative(_, _, components) then
-          extract_extern_type(t, extract_extern_type(components, so_far))
+          extract_extern_type(t, extract_extern_type(components, so_far, beside_type), beside_type)
       }
   }
 .
@@ -174,10 +219,11 @@ define List(Extern_type)
 public define List(Extern_type)
   get_all_extern_type
   (
-    DS_Type ds_type
+    DS_Type       ds_type,    //Type from which we want to extract the extern types
+    List(DS_Type) beside_type //all known type in same file
   )=
   since ds_type is ds_type(_, _, ds_alternatives),
-  extract_extern_type(ds_alternatives, [])
+  extract_extern_type(ds_alternatives, [], beside_type)
 .
 
  /******************* DUMP function *****************************/
--
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