diff --git a/ZCppMain/ZMainHead.H b/ZCppMain/ZMainHead.H
index 6761bf6..cb7266b 100644
--- a/ZCppMain/ZMainHead.H
+++ b/ZCppMain/ZMainHead.H
@@ -3645,7 +3645,8 @@ namespace ZNsMain
               VO_ZCObjtChain.SetDataRecur<1>(9999);
 
           와, 멤버 변수 변경이 이렇게 깔끔하게 될 수 있다니...
-          C++ 진짜 멋지다!
+
+          C++ 진짜 멋지다!  template operator=() 가 있어서 가능했다.
 
           -- 2025-10-22 19:41
 
@@ -3993,6 +3994,85 @@ namespace ZNsMain
 
 
 
+    /*###################################################################
+
+    ■  template<typename TDataChain, int TInIndexNo> class ZtCTypeByNo
+
+        ZtCTypeChain, ZtCObjtChain 등을 template 인자로 받아, 어떤 index
+        숫자로부터 type 을 알 수 있게 한다. index 는 0 부터 시작한다.
+
+        이러면 ZtCObjtChain 의 활용성이 점점 높어지는 것이다. -- 2025-10-23 19:47
+
+    ■  예제 -- 2025-10-23 19:55
+
+        typedef ZtCObjtChain
+        <
+            char  , ZtCObjtChain<
+            string, ZtCObjtChain<
+            double, ZtCObjtChain<
+            int   ,
+            ZCEmpty > > >
+        > ZCObjtChain;  ZCObjtChain VO_ZCObjtChain;
+
+        VO_ZCObjtChain.GetChainNext().GetData()="abc";
+        *VO_ZCObjtChain       ='Z'      ;
+        *VO_ZCObjtChain()     ="New Str";
+        *VO_ZCObjtChain()()   =0.8      ;
+        *VO_ZCObjtChain()()() =1234     ;
+        VO_ZCObjtChain.IterHead(VO_ZCTypeView);
+
+        typedef ZtCTypeByNo<ZCObjtChain, 0>::TypeData  TypeDataHere0 ;
+        typedef ZtCTypeByNo<ZCObjtChain, 1>::TypeData  TypeDataHere1 ;
+        typedef ZtCTypeByNo<ZCObjtChain, 2>::TypeData  TypeDataHere2 ;
+        typedef ZtCTypeByNo<ZCObjtChain, 3>::TypeData  TypeDataHere3 ;
+        typedef ZtCTypeByNo<ZCObjtChain, 4>::TypeData  TypeDataHere4 ;
+
+        typedef ZtCTypeByNo<ZCObjtChain, 0>::TypeChain TypeChainHere0;
+        typedef ZtCTypeByNo<ZCObjtChain, 1>::TypeChain TypeChainHere1;
+        typedef ZtCTypeByNo<ZCObjtChain, 2>::TypeChain TypeChainHere2;
+        typedef ZtCTypeByNo<ZCObjtChain, 3>::TypeChain TypeChainHere3;
+        typedef ZtCTypeByNo<ZCObjtChain, 4>::TypeChain TypeChainHere4;
+
+        cout<<"# TypeDataHere0 ="<<typeid(TypeDataHere0 ).name()<<endl;
+        cout<<"# TypeDataHere1 ="<<typeid(TypeDataHere1 ).name()<<endl;
+        cout<<"# TypeDataHere2 ="<<typeid(TypeDataHere2 ).name()<<endl;
+        cout<<"# TypeDataHere3 ="<<typeid(TypeDataHere3 ).name()<<endl;
+        cout<<"# TypeDataHere4 ="<<typeid(TypeDataHere4 ).name()<<endl;
+
+        cout<<"# TypeChainHere0="<<typeid(TypeChainHere0).name()<<endl;
+        cout<<"# TypeChainHere1="<<typeid(TypeChainHere1).name()<<endl;
+        cout<<"# TypeChainHere2="<<typeid(TypeChainHere2).name()<<endl;
+        cout<<"# TypeChainHere3="<<typeid(TypeChainHere3).name()<<endl;
+        cout<<"# TypeChainHere4="<<typeid(TypeChainHere4).name()<<endl;
+
+    ###################################################################*/
+
+    template<typename TDataChain, int TInIndexNo> class ZtCTypeByNo
+    {
+    public:
+        typedef ZtCTypeByNo /*++++++++++++++++++++++++++++++++*/
+            <
+                typename TDataChain::TypeChainNext, TInIndexNo-1
+            >
+        ZCTypeByNoNext ; /*+++++++++++++++++++++++++++++++++++*/
+
+        typedef typename ZCTypeByNoNext::TypeData     TypeData ;
+        typedef typename ZCTypeByNoNext::TypeChain    TypeChain;
+    public:
+    };/*
+    :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
+
+    template<typename TDataChain> class ZtCTypeByNo<TDataChain, 0>
+    {
+    public:
+        typedef /*----*/ TDataChain  /*----*/ TypeChain;
+        typedef typename TDataChain::TypeData TypeData ;
+    public:
+    };/*
+    :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
+
+
+
     /*///////////////////////////////////////////////////////////////////
 
     ■  class ZtCMiniValChain<>
diff --git a/ZCppMainTest/c++_test_006.cpp b/ZCppMainTest/c++_test_006.cpp
index 0c63c24..d5d0fae 100644
--- a/ZCppMainTest/c++_test_006.cpp
+++ b/ZCppMainTest/c++_test_006.cpp
@@ -220,6 +220,33 @@ namespace ZNsMain
             cout<<"************************************"<<endl;
 
 
+            typedef ZtCTypeByNo<ZCObjtChain, 0>::TypeData  TypeDataHere0 ;
+            typedef ZtCTypeByNo<ZCObjtChain, 1>::TypeData  TypeDataHere1 ;
+            typedef ZtCTypeByNo<ZCObjtChain, 2>::TypeData  TypeDataHere2 ;
+            typedef ZtCTypeByNo<ZCObjtChain, 3>::TypeData  TypeDataHere3 ;
+            typedef ZtCTypeByNo<ZCObjtChain, 4>::TypeData  TypeDataHere4 ;
+
+            typedef ZtCTypeByNo<ZCObjtChain, 0>::TypeChain TypeChainHere0;
+            typedef ZtCTypeByNo<ZCObjtChain, 1>::TypeChain TypeChainHere1;
+            typedef ZtCTypeByNo<ZCObjtChain, 2>::TypeChain TypeChainHere2;
+            typedef ZtCTypeByNo<ZCObjtChain, 3>::TypeChain TypeChainHere3;
+            typedef ZtCTypeByNo<ZCObjtChain, 4>::TypeChain TypeChainHere4;
+
+            cout<<"# TypeDataHere0 ="<<typeid(TypeDataHere0 ).name()<<endl;
+            cout<<"# TypeDataHere1 ="<<typeid(TypeDataHere1 ).name()<<endl;
+            cout<<"# TypeDataHere2 ="<<typeid(TypeDataHere2 ).name()<<endl;
+            cout<<"# TypeDataHere3 ="<<typeid(TypeDataHere3 ).name()<<endl;
+            cout<<"# TypeDataHere4 ="<<typeid(TypeDataHere4 ).name()<<endl;
+            cout<<"************************************"<<endl;
+
+            cout<<"# TypeChainHere0="<<typeid(TypeChainHere0).name()<<endl;
+            cout<<"# TypeChainHere1="<<typeid(TypeChainHere1).name()<<endl;
+            cout<<"# TypeChainHere2="<<typeid(TypeChainHere2).name()<<endl;
+            cout<<"# TypeChainHere3="<<typeid(TypeChainHere3).name()<<endl;
+            cout<<"# TypeChainHere4="<<typeid(TypeChainHere4).name()<<endl;
+            cout<<"************************************"<<endl;
+
+
             typedef ZtCDataRing<std::string> ZCDataRing;
 
             ZCDataRing VO_CDataRing = string("123");