diff --git a/src/include/array/aindex.cc.h b/src/include/array/aindex.cc.h
new file mode 100644
index 0000000..3929ee0
--- /dev/null
+++ b/src/include/array/aindex.cc.h
@@ -0,0 +1,216 @@
+
+#ifndef __cxz_aindex_cc_h__
+#define __cxz_aindex_cc_h__
+
+#include "aindex.h"
+#include "statics/static_for.h"
+
+namespace CNORXZ
+{
+
+    template <typename T>
+    AIndex<T>::AIndex(const T* data, const RangePtr& range, SizeT pos):
+	IndexInterface<AIndex<T>,DType>(pos),
+	mRangePtr(rangeCast<YRange>(range)), mIs(mRangePtr->dim()),
+	mBlockSizes(mRangePtr->dim()), mExternalControl(false),
+	mCData(data)
+    {
+	assert(0);
+	// init ...!!!
+    }
+	
+    template <typename T>
+    AIndex<T>& AIndex<T>::operator=(SizeT pos)
+    {
+	IB::mPos = pos;
+	assert(0);
+	// sub inds... (LAZY!!!) !!!
+	return *this;
+    }
+
+    template <typename T>
+    AIndex<T>& AIndex<T>::operator++()
+    {
+	if(mExternalControl) this->sync();
+	assert(0);
+	// increment sub inds (LAZY!!!) !!!
+	++IB::mPos;
+	return *this;
+    }
+
+    template <typename T>
+    AIndex<T>& AIndex<T>::operator--()
+    {
+	if(mExternalControl) this->sync();
+	assert(0);
+	// decrement sub inds (LAZY!!!) !!!
+	--IB::mPos;
+	return *this;
+    }
+
+    template <typename T>
+    AIndex<T> AIndex<T>::operator+(Int n) const
+    {
+	assert(0);
+	// sub inds !!!
+	return AIndex<T>(mCData, mRangePtr, IB::mPos + n);
+    }
+    
+    template <typename T>
+    AIndex<T> AIndex<T>::operator-(Int n) const
+    {
+	assert(0);
+	// sub inds !!!
+	return AIndex<T>(mCData, mRangePtr, IB::mPos - n);
+    }
+    
+    template <typename T>
+    AIndex<T>& AIndex<T>::operator+=(Int n)
+    {
+	assert(0);
+	// sub inds !!!
+	IB::mPos += n;
+	return *this;
+    }
+    
+    template <typename T>
+    AIndex<T>& AIndex<T>::operator-=(Int n)
+    {
+	assert(0);
+	// sub inds !!!
+	IB::mPos -= n;
+	return *this;
+    }
+
+    template <typename T>
+    const T& AIndex<T>::operator*() const
+    {
+	assert(0);
+	// sub inds !!!
+	return mCData[IB::mPos];
+    }
+    
+    template <typename T>
+    const T* AIndex<T>::operator->() const
+    {
+	assert(0);
+	// sub inds !!!
+	return mCData+IB::mPos;
+    }
+	
+    template <typename T>
+    int AIndex<T>::pp(PtrId idxPtrNum)
+    {
+	assert(0);
+	// sub inds !!!
+	return 0;
+    }
+
+    template <typename T>
+    int AIndex<T>::mm(PtrId idxPtrNum)
+    {
+	assert(0);
+	// sub inds !!!
+	return 0;
+    }
+
+    template <typename T>
+    SizeT AIndex<T>::dim() const
+    {
+	return mIs.size();
+    }
+
+    template <typename T>
+    RangePtr AIndex<T>::range() const
+    {
+	return mRangePtr;
+    }
+
+    template <typename T>
+    SizeT AIndex<T>::getStepSize(SizeT n) const
+    {
+	assert(0);
+	// sub inds !!!
+	return 0;
+    }
+
+    template <typename T>
+    String AIndex<T>::stringMeta() const
+    {
+	String out = "[";
+	auto it = mIs.begin();
+	for(; it != mIs.end()-1; ++it){
+	    out += (*it)->stringMeta() + ",";
+	}
+	out += (*it)->stringMeta() + "]";
+	return out;
+    }
+
+    template <typename T>
+    DType AIndex<T>::meta() const
+    {
+	//this->sync();
+	Vector<DType> v(mIs.size());
+	std::transform(mIs.begin(), mIs.end(), v.begin(), [](auto& x) { return x->meta(); });
+	return DType(v);
+    }
+
+    template <typename T>
+    AIndex<T>& AIndex<T>::at(const DType& meta)
+    {
+	auto& v = std::any_cast<const Vector<DType>&>(meta.get());
+	assert(v.size() == mIs.size());
+	for(SizeT i = 0; i != mIs.size(); ++i){
+	    mIs[i]->at(v[i]);
+	}
+	return *this;
+    }
+    /*
+    template <typename T>
+    DExpr AIndex<T>::ifor(SizeT step, DExpr ex) const
+    {
+	return mI->ifor(step, ex);
+    }
+
+    template <typename T>
+    DExpr AIndex<T>::iforh(SizeT step, DExpr ex) const
+    {
+	return mI->iforh(step, ex);
+    }
+    */
+
+    template <typename T>
+    BIndex<T>::BIndex(T* data, const RangePtr& range, SizeT pos) :
+	AIndex<T>(data, range, pos), mData(data) {}
+
+    template <typename T>
+    BIndex<T>::BIndex(T* data, const AIndex<T>& ai, SizeT pos) :
+	AIndex<T>(data, ai.range(), pos), mData(data) {}
+
+    template <typename T>
+    BIndex<T> BIndex<T>::operator+(Int n) const
+    {
+	return BIndex<T>(mData, IB::mRangePtr, IB::mPos + n);
+    }
+    
+    template <typename T>
+    BIndex<T> BIndex<T>::operator-(Int n) const
+    {
+	return BIndex<T>(mData, IB::mRangePtr, IB::mPos - n);
+    }
+
+    template <typename T>
+    T& BIndex<T>::operator*()
+    {
+	return mData[AI::mPos];
+    }
+
+    template <typename T>
+    T* BIndex<T>::operator->()
+    {
+	return mData+AI::mPos;
+    }
+
+}
+
+#endif
diff --git a/src/include/array/aindex.h b/src/include/array/aindex.h
new file mode 100644
index 0000000..9cc8599
--- /dev/null
+++ b/src/include/array/aindex.h
@@ -0,0 +1,87 @@
+
+#ifndef __cxz_aindex_h__
+#define __cxz_aindex_h__
+
+#include "ranges/range_base.h"
+#include "ranges/index_base.h"
+#include "ranges/xfor/xfor.h"
+#include "ranges/xindex.h"
+#include "ranges/yrange.h"
+
+namespace CNORXZ
+{
+
+    // rename: AIndex (A = Array)
+    // implementation similar to YIndex
+    template <typename T>
+    class AIndex : public IndexInterface<AIndex<T>,DType>
+    {
+    public:
+	typedef IndexInterface<AIndex<T>,DType> IB;
+
+	DEFAULT_MEMBERS(AIndex);
+	AIndex(const T* data, const RangePtr& range, SizeT pos = 0);
+	
+	AIndex& sync(); // recalculate 'IB::mPos' when externalControl == true
+	AIndex& operator()(const Vector<XIndexPtr>& inds); // control via external indice
+	AIndex& operator()(); // -> sync; just to shorten the code
+
+    	AIndex& operator=(SizeT pos);
+	AIndex& operator++();
+	AIndex& operator--();
+	AIndex operator+(Int n) const;
+	AIndex operator-(Int n) const;
+	AIndex& operator+=(Int n);
+	AIndex& operator-=(Int n);
+	
+	const T& operator*() const;
+	const T* operator->() const;
+
+	Int pp(PtrId idxPtrNum);
+	Int mm(PtrId idxPtrNum);
+
+	SizeT dim() const;
+	RangePtr range() const;
+	SizeT getStepSize(SizeT n) const;
+
+	String stringMeta() const;
+	DType meta() const;
+	AIndex& at(const DType& meta);
+
+	//DExpr ifor(SizeT step, DExpr ex) const;
+	//DExpr iforh(SizeT step, DExpr ex) const;
+
+    protected:
+	Sptr<YRange> mRangePtr;
+	Vector<XIndexPtr> mIs;
+	Vector<SizeT> mBlockSizes; // dim() elements only!!!
+	bool mExternalControl = false;
+	const T* mCData = nullptr;
+
+    };
+
+    // BIndex (because B comes after A...)
+    template <typename T>
+    class BIndex : public AIndex<T>
+    {
+    public:
+	typedef AIndex<T> AI;
+	typedef typename AI::IB IB;
+	
+	DEFAULT_MEMBERS(BIndex);
+	BIndex(T* data, const RangePtr& range, SizeT pos = 0);
+	BIndex(T* data, const AIndex<T>& cci, SizeT pos = 0);
+
+	BIndex operator+(Int n) const;
+	BIndex operator-(Int n) const;
+
+	T& operator*();
+	T* operator->();
+
+    private:
+	T* mData = nullptr;
+
+    };
+}
+
+#endif
diff --git a/src/include/array/array.cc.h b/src/include/array/array.cc.h
index fbc55db..ce33281 100644
--- a/src/include/array/array.cc.h
+++ b/src/include/array/array.cc.h
@@ -2,5 +2,5 @@
 //#include "access.cc.h"
 #include "darray_base.cc.h"
 #include "darray.cc.h"
-#include "dcontainer_index.cc.h"
+#include "aindex.cc.h"
 //#include "functional_array.cc.h"
diff --git a/src/include/array/array.h b/src/include/array/array.h
index 183812d..8f07d26 100644
--- a/src/include/array/array.h
+++ b/src/include/array/array.h
@@ -2,7 +2,7 @@
 //#include "access.h"
 #include "darray_base.h"
 #include "darray.h"
-#include "dcontainer_index.h"
+#include "aindex.h"
 //#include "functional_array.h"
 
 #include "array.cc.h"
diff --git a/src/include/array/darray_base.cc.h b/src/include/array/darray_base.cc.h
index 7e09dd1..a64e8df 100644
--- a/src/include/array/darray_base.cc.h
+++ b/src/include/array/darray_base.cc.h
@@ -28,7 +28,7 @@ namespace CNORXZ
     }
 
     template <typename T>
-    size_t DArrayBase<T>::size() const
+    SizeT DArrayBase<T>::size() const
     {
 	return mRange->size();
     }
diff --git a/src/include/array/darray_base.h b/src/include/array/darray_base.h
index 1a65be4..c7491bf 100644
--- a/src/include/array/darray_base.h
+++ b/src/include/array/darray_base.h
@@ -8,7 +8,7 @@
 #include <algorithm>
 
 #include "base/base.h"
-#include "dcontainer_index.h"
+#include "aindex.h"
 //#include "operation/"
 
 namespace CNORXZ
@@ -17,7 +17,7 @@ namespace CNORXZ
     class DArrayBase
     {
     public:
-	typedef DConstContainerIndex<T> const_iterator;
+	typedef AIndex<T> const_iterator;
 
     protected:
 	RangePtr mRange;
@@ -37,10 +37,10 @@ namespace CNORXZ
 	const T& at(const IndexInterface<I,M>& i) const;
 
 	template <typename I, typename M>
-	DArrayBase sl(const IndexInterface<I,M>& i) const;
+	Sptr<DArrayBase<T>> sl(const IndexInterface<I,M>& i) const;
 	
 	virtual const T* data() const = 0;
-	virtual size_t size() const;
+	virtual SizeT size() const;
 	virtual RangePtr range() const;
 
 	virtual const_iterator begin() const;
@@ -61,7 +61,7 @@ namespace CNORXZ
     public:
 	typedef DArrayBase<T> DAB;
 	typedef typename DAB::const_iterator const_iterator;
-	typedef DContainerIndex<T> iterator;
+	typedef BIndex<T> iterator;
 
 	using DAB::operator[];
 	using DAB::at;
@@ -82,7 +82,7 @@ namespace CNORXZ
 	T& at(const IndexInterface<I,M>& i);
 
 	template <typename I, typename M>
-	std::shared_ptr<DArrayBase<T>> sl(const IndexInterface<I,M>& i);
+	Sptr<MDArrayBase<T>> sl(const IndexInterface<I,M>& i);
 
 	virtual T* data() = 0;
 	
diff --git a/src/include/array/dcontainer_index.cc.h b/src/include/array/dcontainer_index.cc.h
deleted file mode 100644
index f9a5d62..0000000
--- a/src/include/array/dcontainer_index.cc.h
+++ /dev/null
@@ -1,134 +0,0 @@
-
-#ifndef __cxz_dcontainer_index_cc_h__
-#define __cxz_dcontainer_index_cc_h__
-
-#include "dcontainer_index.h"
-#include "statics/static_for.h"
-
-namespace CNORXZ
-{
-
-    template <typename T>
-    DConstContainerIndex<T>::DConstContainerIndex(const T* data, const RangePtr& range):
-	mI(range->begin()), mCData(data)
-    {
-	assert(0);
-    }
-	
-    template <typename T>
-    DConstContainerIndex<T>& DConstContainerIndex<T>::operator=(SizeT pos)
-    {
-	(*mI) = pos;
-	IB::mPos = mI->pos();
-	return *this;
-    }
-
-    template <typename T>
-    DConstContainerIndex<T>& DConstContainerIndex<T>::operator++()
-    {
-	++(*mI);
-	IB::mPos = mI->pos();
-	return *this;
-    }
-
-    template <typename T>
-    DConstContainerIndex<T>& DConstContainerIndex<T>::operator--()
-    {
-	--(*mI);
-	IB::mPos = mI->pos();
-	return *this;
-    }
-
-    template <typename T>
-    int DConstContainerIndex<T>::pp(PtrId idxPtrNum)
-    {
-	return mI->pp(idxPtrNum);
-    }
-
-    template <typename T>
-    int DConstContainerIndex<T>::mm(PtrId idxPtrNum)
-    {
-	return mI->mm(idxPtrNum);
-    }
-
-    template <typename T>
-    SizeT DConstContainerIndex<T>::dim() const
-    {
-	return mI->dim();
-    }
-
-    template <typename T>
-    SizeT DConstContainerIndex<T>::getStepSize(SizeT n) const
-    {
-	return mI->getStepSize(n); // dim() elements only!!!
-    }
-
-    template <typename T>
-    String DConstContainerIndex<T>::stringMeta() const
-    {
-	return mI->stringMeta();
-    }
-
-    template <typename T>
-    DType DConstContainerIndex<T>::meta() const
-    {
-	return mI->meta();
-    }
-
-    template <typename T>
-    DConstContainerIndex<T>& DConstContainerIndex<T>::at(const DType& meta)
-    {
-	mI->at(meta);
-	IB::mPos = mI->pos();
-	return *this;
-    }
-    /*
-    template <typename T>
-    DExpr DConstContainerIndex<T>::ifor(SizeT step, DExpr ex) const
-    {
-	return mI->ifor(step, ex);
-    }
-
-    template <typename T>
-    DExpr DConstContainerIndex<T>::iforh(SizeT step, DExpr ex) const
-    {
-	return mI->iforh(step, ex);
-    }
-    */
-    template <typename T>
-    const T& DConstContainerIndex<T>::operator*() const
-    {
-	//this->sync();
-	return mCData[mI->pos()];
-    }
-
-    template <typename T>
-    const T* DConstContainerIndex<T>::operator->() const
-    {
-	//this->sync();
-	return mCData+mI->pos();
-    }
-
-    template <typename T>
-    DContainerIndex<T>::DContainerIndex(T* data, const RangePtr& range) :
-	DConstContainerIndex<T>(range), mData(data) {}
-
-    template <typename T>
-    DContainerIndex<T>::DContainerIndex(T* data, const DConstContainerIndex<T>& cci) :
-	DConstContainerIndex<T>(data, cci.range()), mData(data) {}
-    
-    template <typename T>
-    T& DContainerIndex<T>::operator*()
-    {
-	return mData[CCI::mI->pos()];
-    }
-
-    template <typename T>
-    T* DContainerIndex<T>::operator->()
-    {
-	return mData+CCI::mI->pos();
-    }
-
-}
-
-#endif
diff --git a/src/include/array/dcontainer_index.h b/src/include/array/dcontainer_index.h
deleted file mode 100644
index 1bb3359..0000000
--- a/src/include/array/dcontainer_index.h
+++ /dev/null
@@ -1,74 +0,0 @@
-
-#ifndef __cxz_dcontainer_index_h__
-#define __cxz_dcontainer_index_h__
-
-#include "ranges/range_base.h"
-#include "ranges/index_base.h"
-#include "ranges/xfor/xfor.h"
-#include "ranges/xindex.h"
-#include "ranges/yrange.h"
-
-namespace CNORXZ
-{
-
-    // rename: AIndex (A = Array)
-    template <typename T>
-    class DConstContainerIndex : public IndexInterface<DConstContainerIndex<T>,DType>
-    {
-    public:
-	typedef IndexInterface<DConstContainerIndex<T>,DType> IB;
-
-    protected:
-	YIndexPtr mI;
-	const T* mCData = nullptr;
-
-    public:
-	DEFAULT_MEMBERS(DConstContainerIndex);
-	DConstContainerIndex(const T* data, const RangePtr& range);
-	
-    	DConstContainerIndex& operator=(SizeT pos);
-	DConstContainerIndex& operator++();
-	DConstContainerIndex& operator--();
-	
-	int pp(PtrId idxPtrNum);
-	int mm(PtrId idxPtrNum);
-	SizeT dim() const;
-	SizeT getStepSize(SizeT n) const;
-	String stringMeta() const;
-	DType meta() const;
-	DType metaPtr() const;
-	DConstContainerIndex& at(const DType& meta);
-	//DExpr ifor(SizeT step, DExpr ex) const;
-	//DExpr iforh(SizeT step, DExpr ex) const;
-
-	const T& operator*() const;
-	const T* operator->() const;
-
-	DConstContainerIndex& sync(); // recalculate 'IB::mPos' when externalControl == true
-	DConstContainerIndex& operator()(const std::vector<XIndexPtr>& inds); // control via external indice
-	DConstContainerIndex& operator()(); // -> sync; just to shorten the code
-	
-    };
-
-    template <typename T>
-    class DContainerIndex : public DConstContainerIndex<T>
-    {
-    public:
-	typedef DConstContainerIndex<T> CCI;
-	typedef typename CCI::IB IB;
-	
-    private:
-	T* mData = nullptr;
-
-    public:
-	
-	DEFAULT_MEMBERS(DContainerIndex);
-	DContainerIndex(T* data, const RangePtr& range);
-	DContainerIndex(T* data, const DConstContainerIndex<T>& cci);
-
-	T& operator*();
-	T* operator->();
-    };
-}
-
-#endif
diff --git a/src/include/base/types.h b/src/include/base/types.h
index b4c76c5..455587d 100644
--- a/src/include/base/types.h
+++ b/src/include/base/types.h
@@ -59,11 +59,14 @@ namespace CNORXZ
 	S = Static
 	P = Partial = Sub
 	C = Classic
-	M = Multi or !const
+	M = Multi (Index,Ranges) or !const (Container)
 	U = One(=Uni) dimensional
 	N = None = Null
+	E = Extension (SSE,AVX,etc dof)
 	T = Thread
 	R = Rank
+	A = (const) Array
+	B = (mutable) Array
      ***/
     
     // definition: base/dtype.h
diff --git a/src/include/ranges/yrange.cc.h b/src/include/ranges/yrange.cc.h
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/src/include/ranges/yrange.cc.h
@@ -0,0 +1 @@
+
diff --git a/src/include/ranges/yrange.h b/src/include/ranges/yrange.h
index 4bf7077..9337c0b 100644
--- a/src/include/ranges/yrange.h
+++ b/src/include/ranges/yrange.h
@@ -24,7 +24,7 @@ namespace CNORXZ
 	YIndex(const RangePtr& range, SizeT pos = 0);
 	YIndex(const RangePtr& range, const Vector<XIndexPtr>& is, SizeT pos = 0);
 
-	YIndex& sync();
+	YIndex& sync(); // remove!!!
 
 	YIndex& operator=(SizeT pos);
 	YIndex& operator++();
@@ -56,7 +56,6 @@ namespace CNORXZ
 	Sptr<YRange> mRangePtr;
 	Vector<XIndexPtr> mIs;
 	Vector<SizeT> mBlockSizes; // dim() elements only!!!
-	bool mExternalControl = false;
 
     };
 
diff --git a/src/lib/ranges/yrange.cc b/src/lib/ranges/yrange.cc
index 1443a76..9b5e41a 100644
--- a/src/lib/ranges/yrange.cc
+++ b/src/lib/ranges/yrange.cc
@@ -10,7 +10,7 @@ namespace CNORXZ
     YIndex::YIndex(const RangePtr& range, SizeT pos) :
 	IndexInterface<YIndex,DType>(pos),
 	mRangePtr(rangeCast<YRange>(range)), mIs(mRangePtr->dim()),
-	mBlockSizes(mRangePtr->dim()), mExternalControl(false)
+	mBlockSizes(mRangePtr->dim())
     {
 	assert(0);
 	// init ...!!!
@@ -19,7 +19,7 @@ namespace CNORXZ
     YIndex::YIndex(const RangePtr& range, const Vector<XIndexPtr>& is, SizeT pos) :
 	IndexInterface<YIndex,DType>(pos),
 	mRangePtr(rangeCast<YRange>(range)), mIs(is),
-	mBlockSizes(mRangePtr->dim()), mExternalControl(false)
+	mBlockSizes(mRangePtr->dim())
     {
 	CXZ_ASSERT(mIs.size() == mRangePtr->dim(), "obtained wrong number of indices");
 	assert(0);
@@ -42,7 +42,6 @@ namespace CNORXZ
     
     YIndex& YIndex::operator++()
     {
-	if(mExternalControl) this->sync();
 	assert(0);
 	// increment sub inds (LAZY!!!) !!!
 	++mPos;
@@ -51,7 +50,6 @@ namespace CNORXZ
     
     YIndex& YIndex::operator--()
     {
-	if(mExternalControl) this->sync();
 	assert(0);
 	// decrement sub inds (LAZY!!!) !!!
 	--mPos;
@@ -91,14 +89,12 @@ namespace CNORXZ
     DType YIndex::operator*() const
     {
 	assert(0);
-	// sub inds !!!
 	return DType();
     }
     
     DType YIndex::operator->() const
     {
 	assert(0);
-	// sub inds !!!
 	return DType();
     }
 	
@@ -141,7 +137,6 @@ namespace CNORXZ
    
     DType YIndex::meta() const
     {
-	//this->sync();
 	Vector<DType> v(mIs.size());
 	std::transform(mIs.begin(), mIs.end(), v.begin(), [](auto& x) { return x->meta(); });
 	return DType(v);