diff --git a/Framework/StackInterface/StackIteratorInterface.h b/Framework/StackInterface/StackIteratorInterface.h
index b790c4955f2fd62ed458a154fa7f9e594c97bac7..f420be28812f0ba619186242dabce8a6672f92c5 100644
--- a/Framework/StackInterface/StackIteratorInterface.h
+++ b/Framework/StackInterface/StackIteratorInterface.h
@@ -12,8 +12,7 @@
 
 namespace corsika::history {
   template <typename T, template <typename> typename ParticleInterface>
-  // class HistorySecondaryView; // forward decl. for befriending
-  class HistorySecondaryProducer;
+    class HistorySecondaryProducer; // forward decl.
 }
 
 namespace corsika::stack {
@@ -22,7 +21,6 @@ namespace corsika::stack {
   class Stack; // forward decl
 
   template <typename TStackData, template <typename> typename TParticleInterface,
-            // template <typename> typename TProd>
             template <class T1, template <class> class T2> class MSecondaryProducer>
   class SecondaryView; // forward decl
 
@@ -86,17 +84,14 @@ namespace corsika::stack {
                                                          // SecondaryView : public Stack
     friend class ParticleBase<StackIteratorInterface>;   // for access to GetStackData
 
-    template <typename T1,                     //=TStackData,
-              template <typename> typename M1, //=TParticleInterface,
+    template <typename T1,                     // best fix this to: TStackData,
+              template <typename> typename M1, // best fix this to: TParticleInterface,
               template <typename T, template <typename> typename T3> typename M2>
-    //              template <typename> typename M2>
-    friend class SecondaryView; //<TStackData,TParticleInterface,M>; // access for
-                                // SecondaryView
+    friend class SecondaryView;                // access grant for SecondaryView
 
     template <typename T, template <typename> typename ParticleInterface>
-    // friend class corsika::history::HistorySecondaryView;
     friend class corsika::history::HistorySecondaryProducer;
-
+  
     friend class ConstStackIteratorInterface<TStackData, TParticleInterface, StackType>;
 
   protected:
@@ -256,25 +251,19 @@ namespace corsika::stack {
     friend class Stack<TStackData,
                        TParticleInterface>; // for access to GetIndex for Stack
     friend class Stack<TStackData&, TParticleInterface>; // for access to GetIndex
-                                                         // SecondaryView : public Stack
+
     friend class ParticleBase<
         ConstStackIteratorInterface>; // for access to GetStackData
-                                      // friend class SecondaryView<TStackData,
-                                      //                           TParticleInterface>; //
-                                      //                           access for
-                                      //                           SecondaryView
-    template <typename T1,            //=TStackData,
+
+    template <typename T1,            // best fix to: TStackData,
               template <typename>
-              typename M1, //=TParticleInterface,
-                           //              template <typename> typename M2>
+              typename M1,            // best fix to: TParticleInterface,
               template <class T2, template <class> class T3> class MSecondaryProducer>
-    friend class SecondaryView; //<TStackData,TParticleInterface,M>; // access for
-                                // SecondaryView
+    friend class SecondaryView;       // access for SecondaryView
 
     friend class StackIteratorInterface<TStackData, TParticleInterface, StackType>;
 
     template <typename T, template <typename> typename ParticleInterface>
-    // friend class corsika::history::HistorySecondaryView;
     friend class corsika::history::HistorySecondaryProducer;
 
   protected: