diff --git a/src/opt/mpi/include/rarray.cc.h b/src/opt/mpi/include/rarray.cc.h
index b1383c4..ee56d1c 100644
--- a/src/opt/mpi/include/rarray.cc.h
+++ b/src/opt/mpi/include/rarray.cc.h
@@ -356,27 +356,29 @@ namespace CNORXZ
 
 	template <typename T>
 	template <class Index>
-	OpRoot<T,Index> RArray<T>::rop(const Sptr<Index>& i)
+	OpRoot<T,Index> RArray<T>::operator()(const Sptr<Index>& i)
+	//OpRoot<T,Index> RArray<T>::rop(const Sptr<Index>& i)
 	{
 	    return (*mB)(i);
 	}
 	
 	template <typename T>
 	template <class... Indices>
-	inline decltype(auto) RArray<T>::rop(const SPack<Indices...>& pack)
+	inline decltype(auto) RArray<T>::operator()(const SPack<Indices...>& pack)
+	//inline decltype(auto) RArray<T>::rop(const SPack<Indices...>& pack)
 	{
 	    typedef typename std::remove_reference<decltype(*pack[CSizeT<0>{}])>::type I0;
 	    if constexpr(is_rank_index<I0>::value){
 		// preliminary:
 		CXZ_ASSERT(mB->formatIsTrivial(),
 			   "array has non-trivial format, rank operations require trivial format");
-		/*
+		
 		auto ri = pack[CSizeT<0>{}];
 		auto li = iter<1,sizeof...(Indices)>
 		    ( [&](auto i) { return pack[CSizeT<i>{}]; },
 		      [](const auto&... x) { return mindexPtr( (x * ...) ); } );
-		*/
-		return oproot(*mB, mindexPtr(pack));
+		return roproot(*this, ri, li);
+		//return oproot(*mB, mindexPtr(pack));
 	    }
 	    else {
 		return (*mB)(pack);
@@ -384,7 +386,8 @@ namespace CNORXZ
 	}
 	
 	template <typename T>
-	inline decltype(auto) RArray<T>::rop(const DPack& pack)
+	inline decltype(auto) RArray<T>::operator()(const DPack& pack)
+	//inline decltype(auto) RArray<T>::rop(const DPack& pack)
 	{
 	    return (*mB)(pack);
 	}
diff --git a/src/opt/mpi/include/rarray.h b/src/opt/mpi/include/rarray.h
index 1390d82..0782f7b 100644
--- a/src/opt/mpi/include/rarray.h
+++ b/src/opt/mpi/include/rarray.h
@@ -221,14 +221,17 @@ namespace CNORXZ
 
 	    /** @copydoc ArrayBase::operator() */
 	    template <class Index>
-	    OpRoot<T,Index> rop(const Sptr<Index>& i);
+	    OpRoot<T,Index> operator()(const Sptr<Index>& i);
+	    //OpRoot<T,Index> rop(const Sptr<Index>& i);
 
 	    /** @copydoc ArrayBase::operator() */
 	    template <class... Indices>
-	    inline decltype(auto) rop(const SPack<Indices...>& pack);
+	    inline decltype(auto) operator()(const SPack<Indices...>& pack);
+	    //inline decltype(auto) rop(const SPack<Indices...>& pack);
 
 	    /** @copydoc ArrayBase::operator() */
-	    inline decltype(auto) rop(const DPack& pack);
+	    inline decltype(auto) operator()(const DPack& pack);
+	    //inline decltype(auto) rop(const DPack& pack);
 
 	    /** @copydoc ArrayBase::data() */
 	    T* data();
diff --git a/src/opt/mpi/include/rop_types.cc.h b/src/opt/mpi/include/rop_types.cc.h
index 31983c5..3002a00 100644
--- a/src/opt/mpi/include/rop_types.cc.h
+++ b/src/opt/mpi/include/rop_types.cc.h
@@ -56,18 +56,24 @@ namespace CNORXZ
 	template <typename T, class RIndexT, class IndexT>
 	constexpr ROpRoot<T,RIndexT,IndexT>::ROpRoot(RArray<T>& a, const Sptr<RIndexT>& ri,
 						     const Sptr<IndexT>& li) :
-	    mData(a.data()),
+	    mLocal(&a.local()),
+	    mData(a.buffermap().data()),
+	    //mData(a.data()),
 	    mRIndex(ri),
 	    mIndex(li)
 	{
-	    CXZ_ERROR("nope");
+	    //CXZ_ERROR("nope");
+	    CXZ_ASSERT(a.buffermap().size() == ri->lmax().val(),
+		       "data map not properly initialized: map size = " << a.buffermap().size()
+		       << ", rank index range size = " << ri->lmax().val());
 	}
 	
 	template <typename T, class RIndexT, class IndexT>
 	template <class Op>
 	constexpr ROpRoot<T,RIndexT,IndexT>& ROpRoot<T,RIndexT,IndexT>::operator=(const Op& in)
 	{
-	    OI::a(mIndex, [](auto& a, const auto& b) { a = b; }, in);
+	    (*mLocal)(mindexPtr(mRIndex->local()*mIndex)) = in;
+	    //OI::a(mIndex, [](auto& a, const auto& b) { a = b; }, in);
 	    return *this;
 	}
 	
@@ -75,14 +81,16 @@ namespace CNORXZ
 	template <class Op>
 	constexpr ROpRoot<T,RIndexT,IndexT>& ROpRoot<T,RIndexT,IndexT>::operator+=(const Op& in)
 	{
-	    OI::a(mIndex, [](auto& a, const auto& b) { a += b; }, in);
+	    (*mLocal)(mindexPtr(mRIndex->local()*mIndex)) += in;
+	    //OI::a(mIndex, [](auto& a, const auto& b) { a += b; }, in);
 	    return *this;
 	}
 	
 	template <typename T, class RIndexT, class IndexT>
 	constexpr ROpRoot<T,RIndexT,IndexT>& ROpRoot<T,RIndexT,IndexT>::operator=(const ROpRoot& in)
 	{
-	    OI::a(mIndex, [](auto& a, const auto& b) { a = b; }, in);
+	    (*mLocal)(mindexPtr(mRIndex->local()*mIndex)) = in;
+	    //OI::a(mIndex, [](auto& a, const auto& b) { a = b; }, in);
 	    return *this;
 	}
 
@@ -90,20 +98,20 @@ namespace CNORXZ
 	template <class PosT>
 	constexpr decltype(auto) ROpRoot<T,RIndexT,IndexT>::operator()(const PosT& pos) const
 	{
-	    return mData[pos.val()];
+	    return (mData[pos.val()])[pos.next().val()];
 	}
 
 	template <typename T, class RIndexT, class IndexT>
 	constexpr decltype(auto) ROpRoot<T,RIndexT,IndexT>::operator()() const
 	{
-	    return mData[0];
+	    return (mData[0])[0];
 	}
 
 	template <typename T, class RIndexT, class IndexT>
 	template <SizeT I>
 	constexpr decltype(auto) ROpRoot<T,RIndexT,IndexT>::rootSteps(const IndexId<I>& id) const
 	{
-	    return mIndex->stepSize(id);
+	    return mRIndex->stepSize(id) << mIndex->stepSize(id);
 	}
     
 	template <typename T, class RIndexT, class IndexT>
diff --git a/src/opt/mpi/include/rop_types.h b/src/opt/mpi/include/rop_types.h
index 2b10bfa..5415182 100644
--- a/src/opt/mpi/include/rop_types.h
+++ b/src/opt/mpi/include/rop_types.h
@@ -76,7 +76,8 @@ namespace CNORXZ
 
 	private:
 
-	    T* mData;
+	    ArrayBase<T>* mLocal;
+	    const T* const* mData;
 	    Sptr<RIndexT> mRIndex;
 	    Sptr<IndexT> mIndex;
 	};
diff --git a/src/opt/mpi/tests/roperation_unit_test.cc b/src/opt/mpi/tests/roperation_unit_test.cc
index 1a1f50d..ce9b17b 100644
--- a/src/opt/mpi/tests/roperation_unit_test.cc
+++ b/src/opt/mpi/tests/roperation_unit_test.cc
@@ -133,8 +133,10 @@ namespace
 	for(const auto& r: *imap1){
 	    req[r] = true;
 	}
+	res.load(x, AB, req); // DUMMY, not used...
 	mM1.load(xp, AB, req);
-	res.rop(x*A*B) = mapXpr(xp,x,imap1, mM1(xp*A*B) - mM1(x*A*B) );
+	//res.rop(x*A*B) = mapXpr(xp,x,imap1, mM1(xp*A*B) - mM1(x*A*B) );
+	res(x*A*B) = mapXpr(xp,x,imap1, mM1(xp*A*B) - mM1(x*A*B) );
 
 	for(SizeT x0 = 0; x0 != T; ++x0) { 
 	for(SizeT x1 = 0; x1 != L; ++x1)