diff --git a/core/include/Data/ArrayData.h b/core/include/Data/ArrayData.h
index 5cd885b..f33f0a5 100644
--- a/core/include/Data/ArrayData.h
+++ b/core/include/Data/ArrayData.h
@@ -77,6 +77,13 @@ public:
             }
         }
 
+        void prev()
+        {
+            for (auto &it : m_Its) {
+                --it;
+            }
+        }
+
         bool operator==(const IteratorValue &other) const { return m_Its == other.m_Its; }
 
     private:
@@ -105,6 +112,12 @@ public:
             return *this;
         }
 
+        Iterator &operator--()
+        {
+            m_CurrentValue.prev();
+            return *this;
+        }
+
         pointer operator->() const { return &m_CurrentValue; }
         reference operator*() const { return m_CurrentValue; }
 
diff --git a/core/include/Data/DataSeries.h b/core/include/Data/DataSeries.h
index 036a6b1..b2ddacb 100644
--- a/core/include/Data/DataSeries.h
+++ b/core/include/Data/DataSeries.h
@@ -191,7 +191,7 @@ public:
             std::make_unique<dataseries_detail::IteratorValue<Dim> >(*this, false)}};
     }
 
-    std::pair<Iterator, Iterator> subData(double min, double max) const
+    std::pair<DataSeriesIterator, DataSeriesIterator> subData(double min, double max) const override
     {
         if (min > max) {
             std::swap(min, max);
diff --git a/core/include/Data/IDataSeries.h b/core/include/Data/IDataSeries.h
index 7435fa3..7574cab 100644
--- a/core/include/Data/IDataSeries.h
+++ b/core/include/Data/IDataSeries.h
@@ -2,6 +2,7 @@
 #define SCIQLOP_IDATASERIES_H
 
 #include <Common/MetaTypes.h>
+#include <Data/DataSeriesIterator.h>
 #include <Data/SqpRange.h>
 
 #include <memory>
@@ -62,6 +63,20 @@ public:
     virtual std::unique_ptr<IDataSeries> clone() const = 0;
     virtual SqpRange range() const = 0;
 
+    // ///////// //
+    // Iterators //
+    // ///////// //
+
+    virtual DataSeriesIterator cbegin() const = 0;
+    virtual DataSeriesIterator cend() const = 0;
+
+    virtual std::pair<DataSeriesIterator, DataSeriesIterator> subData(double min,
+                                                                      double max) const = 0;
+
+    // /////// //
+    // Mutexes //
+    // /////// //
+
     virtual void lockRead() = 0;
     virtual void lockWrite() = 0;
     virtual void unlock() = 0;