diff --git a/src/include/base/obj_handle.cc.h b/src/include/base/obj_handle.cc.h
index 1d11ee9..8288de4 100644
--- a/src/include/base/obj_handle.cc.h
+++ b/src/include/base/obj_handle.cc.h
@@ -69,6 +69,18 @@ namespace CNORXZ
 	return &*mC;
     }
 
+    template <typename T>
+    T* ObjHandle<T>::get()
+    {
+	return &*mC;
+    }
+    
+    template <typename T>
+    const T* ObjHandle<T>::get() const
+    {
+	return &*mC;
+    }
+
 }
 
 #endif
diff --git a/src/include/base/obj_handle.h b/src/include/base/obj_handle.h
index 02b2b19..ada4e2f 100644
--- a/src/include/base/obj_handle.h
+++ b/src/include/base/obj_handle.h
@@ -77,6 +77,12 @@ namespace CNORXZ
 
 	/** get pointer to data (const) */
 	const T* operator->() const;
+
+	/** get object. */
+	T* get();
+
+	/** get object. */
+	const T* get() const;
     };
     
 }
diff --git a/src/opt/mpi/include/rarray.cc.h b/src/opt/mpi/include/rarray.cc.h
index e94c6e5..054837e 100644
--- a/src/opt/mpi/include/rarray.cc.h
+++ b/src/opt/mpi/include/rarray.cc.h
@@ -21,6 +21,10 @@ namespace CNORXZ
     namespace mpi
     {
 
+	/*===============+
+	 |    RCArray    |
+	 +===============*/
+	
 	template <typename T>
 	RCArray<T>::RCArray(const RCArray& a) :
 	    mA(a.mA->copy()),
@@ -43,6 +47,14 @@ namespace CNORXZ
 	    mGlobal(RRangeFactory(rangeCast<YRange>(a.range()),rangeCast<YRange>(mGeom)).create())
 	{}
 
+	template <typename T>
+	template <class IndexI, class IndexK>
+	RCArray<T>::RCArray(const RRange<IndexI,IndexK>& range) :
+	    mA(std::make_unique<T>(range->local())),
+	    mGeom(range->geom()),
+	    mGlobal(range)
+	{}
+
 	template <typename T>
 	template <typename I, typename M>
 	T RCArray<T>::operator[](const IndexInterface<I,M>& i) const
@@ -241,11 +253,146 @@ namespace CNORXZ
 	Sptr<Vector<SizeT>> RCArray<T>::load(const Sptr<Index>& i, const F& f) const
 	{
 	    Sptr<Vector<SizeT>> imap = std::make_shared<Vector<SizeT>>();
-
+	    CXZ_ERROR("!!!");
 	    //load(i, /**/, imap);
 	    return imap;
 	}
 
+	/*===============+
+	 |    RCArray    |
+	 +===============*/
+
+	template <typename T>
+	RArray<T>::RArray(const RArray& a) :
+	    RCArray<T>(a),
+	    mB(dynamic_cast<ArrayBase<T>*>(RCA::mA.get()))
+	{}
+
+	template <typename T>
+	RArray<T>& RArray<T>::operator=(const RArray& a)
+	{
+	    RCArray<T>::operator=(a);
+	    mB = dynamic_cast<ArrayBase<T>*>(RCA::mA.get());
+	    return *this;
+	}
+
+	template <typename T>
+	template <class IndexI, class IndexK>
+	RArray<T>::RArray(const RRange<IndexI,IndexK>& range) :
+	    RCArray<T>(range),
+	    mB(dynamic_cast<ArrayBase<T>*>(RCA::mA.get()))
+	{}
+	    
+	template <typename T>
+	RArray<T>::RArray(const ArrayBase<T>& a, const RangePtr& geom) :
+	    RCArray<T>(a, geom),
+	    mB(dynamic_cast<ArrayBase<T>*>(RCA::mA.get()))
+	{}
+
+	template <typename T>
+	template <typename I, typename M>
+	RArray<T>& RArray<T>::set(const IndexInterface<I,M>& i, const T& val)
+	{
+	    auto it = begin() + i.lex();
+	    it.set(val);
+	    return *this;
+	}
+
+	template <typename T>
+	template <class... Indices>
+	RArray<T>& RArray<T>::set(const SPack<Indices...>& pack, const T& val)
+	{
+	    auto it = begin() + pack.lex();
+	    it.set(val);
+	    return *this;
+	}
+
+	template <typename T>
+	RArray<T>& RArray<T>::set(const DPack& pack, const T& val)
+	{
+	    auto it = begin() + pack.lex();
+	    it.set(val);
+	    return *this;
+	}
+
+	template <typename T>
+	template <typename I, typename M>
+	Sptr<ArrayBase<T>> RArray<T>::sl(const IndexInterface<I,M>& begin,
+					 const IndexInterface<I,M>& end)
+	{
+	    if constexpr(is_rank_index<I>::value){
+		CXZ_ERROR("not implemented");
+		return nullptr;
+	    }
+	    else {
+		return mB->sl(begin, end);
+	    }
+	}
+
+	template <typename T>
+	template <class Index>
+	OpRoot<T,Index> RArray<T>::operator()(const Sptr<Index>& i)
+	{
+	    CXZ_ERROR("not implemented");
+	    return OpRoot<T,Index>();
+	}
+
+	template <typename T>
+	template <class... Indices>
+	inline decltype(auto) RArray<T>::operator()(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(this->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 croproot(*this, ri, li);
+	    }
+	    else {
+		return (*mB)(pack);
+	    }
+	}
+
+	template <typename T>
+	inline decltype(auto) RArray<T>::operator()(const DPack& pack)
+	{
+	    // TODO: assert that none of the indices is rank index
+	    return (*mB)(pack);
+	}
+
+	template <typename T>
+	T* RArray<T>::data()
+	{
+	    return mB->data();
+	}
+
+	template <typename T>
+	typename RArray<T>::iterator RArray<T>::begin()
+	{
+	    return iterator(mB->data(), RCA::mGlobal);
+	}
+
+	template <typename T>
+	typename RArray<T>::iterator RArray<T>::end()
+	{
+	    return iterator(mB->data(), RCA::mGlobal, RCA::mGlobal->size());
+	}
+	    
+	template <typename T>
+	ArrayBase<T>& RArray<T>::local()
+	{
+	    return *mB;
+	}
+	
+	
+	/*============================+
+	 |    non-member functions    |
+	 +============================*/
+
 	template <class TarI, class RTarI, class SrcI, class RSrcI, typename T>
 	void setupBuffer(const Sptr<RIndex<TarI,RTarI>>& rgi, const Sptr<RIndex<SrcI,RSrcI>>& rgj,
 			 const Sptr<Vector<SizeT>>& imap, const CArrayBase<T>& data,
diff --git a/src/opt/mpi/include/rarray.h b/src/opt/mpi/include/rarray.h
index 0ec4451..62c9cd3 100644
--- a/src/opt/mpi/include/rarray.h
+++ b/src/opt/mpi/include/rarray.h
@@ -33,6 +33,12 @@ namespace CNORXZ
 	    DEFAULT_MOVE(RCArray);
 	    RCArray(const RCArray& a);
 	    RCArray& operator=(const RCArray& a);
+
+	    /** Construct from a rank range.
+		@param range The range.
+	     */
+	    template <class IndexI, class IndexK>
+	    RCArray(const RRange<IndexI,IndexK>& range);
 	    
 	    /** Construct from local array object.
 		@param a Local array.
@@ -153,6 +159,8 @@ namespace CNORXZ
 	{
 	public:
 	    typedef RCArray<T> RCA;
+	    typedef typename RCA::const_iterator const_iterator;
+	    typedef RBIndex<T> iterator;
 	
 	    using RCA::operator[];
 	    using RCA::operator();
@@ -164,9 +172,74 @@ namespace CNORXZ
 	    using RCA::cend;
 	    using RCA::sl;
 
-	    DEFAULT_MEMBERS(RArray);
+	    DEFAULT_C(RArray);
+	    DEFAULT_MOVE(RArray);
+	    RArray(const RArray& a);
+	    RArray& operator=(const RArray& a);
+
+	    /** Construct from a rank range.
+		@param range The range.
+	     */
+	    template <class IndexI, class IndexK>
+	    RArray(const RRange<IndexI,IndexK>& range);
+	    
+	    /** Construct from local array object.
+		@param a Local array.
+		@param geom Rank geometry.
+	     */
+	    RArray(const ArrayBase<T>& a, const RangePtr& geom);
+
+	    /** Assign value at a position indicated by an index.
+		@param i Index indicating the position.
+		@param val Value.
+	     */
+	    template <typename I, typename M>
+	    RArray& set(const IndexInterface<I,M>& i, const T& val);
+
+	    /** Assign value at a position indicated by an index pack.
+		@param pack Index pack indicating the position.
+		@param val Value.
+	     */
+	    template <class... Indices>
+	    RArray& set(const SPack<Indices...>& pack, const T& val);
+
+	    /** Assign value at a position indicated by an index pack.
+		@param pack Index pack indicating the position.
+		@param val Value.
+	     */
+	    RArray& set(const DPack& pack, const T& val);
+
+	    /** @copydoc ArrayBase::sl() */
+	    template <typename I, typename M>
+	    Sptr<ArrayBase<T>> sl(const IndexInterface<I,M>& begin,
+				  const IndexInterface<I,M>& end);
+
+	    /** @copydoc ArrayBase::operator() */
+	    template <class Index>
+	    OpRoot<T,Index> operator()(const Sptr<Index>& i);
+
+	    /** @copydoc ArrayBase::operator() */
+	    template <class... Indices>
+	    inline decltype(auto) operator()(const SPack<Indices...>& pack);
+
+	    /** @copydoc ArrayBase::operator() */
+	    inline decltype(auto) operator()(const DPack& pack);
+
+	    /** @copydoc ArrayBase::data() */
+	    T* data();
+
+	    /** @copydoc ArrayBase::begin() */
+	    iterator begin();
+
+	    /** @copydoc ArrayBase::end() */
+	    iterator end();
+	    
+	    /** Get local array object. */
+	    ArrayBase<T>& local();
+
+	private:
+	    ArrayBase<T>* mB = nullptr;
 
-	
 	};
 
 	template <class TarI, class RTarI, class SrcI, class RSrcI, typename T>