diff --git a/src/lib/diff/tree-mutator-collection-binding.hpp b/src/lib/diff/tree-mutator-collection-binding.hpp
index 505ed3567..e84f66b4f 100644
--- a/src/lib/diff/tree-mutator-collection-binding.hpp
+++ b/src/lib/diff/tree-mutator-collection-binding.hpp
@@ -60,6 +60,8 @@
     using lib::meta::Strip;
     using lib::diff::GenNode;
     
+    
+    /** verify the installed functors or lambdas expose the expected signature */
 #define ASSERT_VALID_SIGNATURE(_FUN_, _SIG_) \
         static_assert (has_Sig<_FUN_, _SIG_>::value, "Function " STRINGIFY(_FUN_) " unsuitable, expected signature: " STRINGIFY(_SIG_));
         
diff --git a/src/lib/diff/tree-mutator.hpp b/src/lib/diff/tree-mutator.hpp
index 645e88bbb..3399ea019 100644
--- a/src/lib/diff/tree-mutator.hpp
+++ b/src/lib/diff/tree-mutator.hpp
@@ -280,6 +280,7 @@ namespace diff{
      * @remarks Solution proposed 10/2011 by \link http://stackoverflow.com/users/224671/kennytm user "kennytm" \endlink
      *          in this \link http://stackoverflow.com/questions/7943525/is-it-possible-to-figure-out-the-parameter-type-and-return-type-of-a-lambda/7943765#7943765
      *          answer on stackoverflow \endlink
+     * @todo this should be integrated into (\ref _Fun)                  //////////////////////////////////////TICKET #994
      */
     template<typename FUN>
     struct _ClosureType
diff --git a/src/lib/meta/function.hpp b/src/lib/meta/function.hpp
index 485f489c0..771e05879 100644
--- a/src/lib/meta/function.hpp
+++ b/src/lib/meta/function.hpp
@@ -34,7 +34,10 @@
  ** specifically tailored bindings.
  ** 
  ** If the following code makes you feel like vomiting, please look away,
- ** and rest assured: you aren't alone. 
+ ** and rest assured: you aren't alone.
+ ** 
+ ** @todo rework to use variadic templates and integrage support for lambdas   //////////////////////////////////////TICKET #994
+ ** 
  ** 
  ** @see control::CommandDef usage example
  ** @see function-closure.hpp generic function application
@@ -216,6 +219,9 @@ namespace meta{
    * irrespective if the parameter is given as function reference,
    * function pointer, member function pointer or functor object.
    * The base case assumes a (language) function reference.
+   * @todo the base case should be a _generic functor_ where we
+   *       pick up the signature through `decltype`, which also
+   *       works with lambdas. See (\ref _ClosureType)                  //////////////////////////////////////TICKET #994
    */
   template<typename SIG>
   struct _Fun