diff --git a/applications/test/sort/sortListTest.C b/applications/test/sort/sortListTest.C
index 34a756dae7..06d5b01186 100644
--- a/applications/test/sort/sortListTest.C
+++ b/applications/test/sort/sortListTest.C
@@ -27,6 +27,7 @@ Description
 \*---------------------------------------------------------------------------*/
 
 #include "SortableList.H"
+#include "ListOps.H"
 
 using namespace Foam;
 
@@ -35,49 +36,101 @@ using namespace Foam;
 
 int main(int argc, char *argv[])
 {
-    labelList orig(5);
+    labelList orig(8);
     orig[0] = 7;
-    orig[1] = 4;
+    orig[1] = 9;
     orig[2] = 1;
     orig[3] = 2;
-    orig[4] = 9;
+    orig[4] = 4;
+    orig[5] = 7;
+    orig[6] = 4;
+    orig[7] = 0;
+
+    labelList order;
 
     labelList a(orig);
-    Info << "before: " << a << endl;
+    sortedOrder(a, order);
+
+    Info<< "unsorted: " << a << endl;
     sort(a);
-    Info << "after:  " << a << endl;
+    Info<< "sorted:   " << a << endl;
+    Info<< "indices:  " << order << endl;
 
     SortableList<label> b(orig);
-    Info << "sorted:  " << b << endl;
-    Info << "indices: " << b.indices() << endl;
+    Info<< "unsorted: " << orig << endl;
+    Info<< "sorted:   " << b << endl;
+    Info<< "indices:  " << b.indices() << endl;
 
-    Info << "shrunk:  " << b.shrink() << endl;
-    Info << "indices: " << b.indices() << endl;
+    Info<< "shrunk:   " << b.shrink() << endl;
+    Info<< "indices:  " << b.indices() << endl;
 
     // repeat by assignment
     b = orig;
-    Info << "unsorted: " << b << endl;
+    Info<< "unsorted: " << b << endl;
     b.sort();
 
-    Info << "sorted:   " << b << endl;
-    Info << "indices:  " << b.indices() << endl;
+    Info<< "sorted:   " << b << endl;
+    Info<< "indices:  " << b.indices() << endl;
+
+    // find unique/duplicate values
+    b = orig;
+
+    Info<< "unsorted: " << b << endl;
+    uniqueOrder(b, order);
+    Info<< "unique:  " << order << endl;
+    duplicateOrder(b, order);
+    Info<< "duplicate:" << order << endl;
+
+    // sort reverse
+    Info<< "unsorted: " << b << endl;
+    b.reverseSort();
+    Info<< "rsort:    " << b << endl;
+    Info<< "indices:  " << b.indices() << endl;
 
     // transfer assignment
-    b.transfer(orig);
-    Info << "unsorted: " << b << endl;
+    a = orig;
+    b.transfer(a);
+    Info<< "unsorted: " << b << endl;
     b.sort();
 
-    Info << "sorted:   " << b << endl;
-    Info << "indices:  " << b.indices() << endl;
+    Info<< "sorted:   " << b << endl;
+    Info<< "indices:  " << b.indices() << endl;
 
-    labelList flatten;
-    flatten.transfer(b);
-    
-    Info << "flatten:  " << flatten << endl;
-    Info << "sorted:   " << b << endl;
-    Info << "indices:  " << b.indices() << endl;
+    a.transfer(b);
 
-    Info << "End\n" << endl;
+    Info<< "plain:    " << a << endl;
+    Info<< "sorted:   " << b << endl;
+    Info<< "indices:  " << b.indices() << endl;
+
+    // sort/duplicate/unique with identical values
+    b.setSize(8);
+    b = 5;
+
+    Info<< "unsorted: " << b << endl;
+
+    uniqueOrder(b, order);
+    Info<< "unique:  " << order << endl;
+    duplicateOrder(b, order);
+    Info<< "duplicate:" << order << endl;
+    b.sort();
+
+    Info<< "sorted:   " << b << endl;
+    Info<< "indices:  " << b.indices() << endl;
+
+    // with a single value
+    b.setSize(1);
+
+    Info<< "unsorted: " << b << endl;
+    uniqueOrder(b, order);
+    Info<< "unique:  " << order << endl;
+    duplicateOrder(b, order);
+    Info<< "duplicate:" << order << endl;
+    b.sort();
+
+    Info<< "sorted:   " << b << endl;
+    Info<< "indices:  " << b.indices() << endl;
+
+    Info<< "\nEnd\n" << endl;
 
     return 0;
 }
diff --git a/src/OpenFOAM/containers/Lists/ListOps/ListOps.H b/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
index 889dd57d7e..67135f957c 100644
--- a/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
+++ b/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
@@ -82,6 +82,13 @@ void inplaceMapKey(const UList<label>& oldToNew, Container&);
 template<class T>
 void sortedOrder(const UList<T>&, labelList& order);
 
+//- Generate (sorted) indices corresponding to duplicate list values
+template<class T>
+void duplicateOrder(const UList<T>&, labelList& order);
+
+//- Generate (sorted) indices corresponding to unique list values
+template<class T>
+void uniqueOrder(const UList<T>&, labelList& order);
 
 //- Extract elements of List whose region is certain value.
 //  Use e.g. to extract all selected elements:
diff --git a/src/OpenFOAM/containers/Lists/ListOps/ListOpsTemplates.C b/src/OpenFOAM/containers/Lists/ListOps/ListOpsTemplates.C
index b048ef1bb8..942cb6e8c0 100644
--- a/src/OpenFOAM/containers/Lists/ListOps/ListOpsTemplates.C
+++ b/src/OpenFOAM/containers/Lists/ListOps/ListOpsTemplates.C
@@ -174,16 +174,65 @@ void Foam::sortedOrder
 )
 {
     order.setSize(lst.size());
-
     forAll(order, elemI)
     {
         order[elemI] = elemI;
     }
-
     Foam::stableSort(order, typename UList<T>::less(lst));
 }
 
 
+template<class T>
+void Foam::duplicateOrder
+(
+    const UList<T>& lst,
+    labelList& order
+)
+{
+    if (lst.size() < 2)
+    {
+        order.clear();
+        return;
+    }
+
+    sortedOrder(lst, order);
+
+    label n = 0;
+    for (label i = 0; i < order.size() - 1; ++i)
+    {
+        if (lst[order[i]] == lst[order[i+1]])
+        {
+            order[n++] = order[i];
+        }
+    }
+    order.setSize(n);
+}
+
+
+template<class T>
+void Foam::uniqueOrder
+(
+    const UList<T>& lst,
+    labelList& order
+)
+{
+    sortedOrder(lst, order);
+
+    if (order.size() > 1)
+    {
+        label n = 0;
+        for (label i = 0; i < order.size() - 1; ++i)
+        {
+            if (lst[order[i]] != lst[order[i+1]])
+            {
+                order[n++] = order[i];
+            }
+        }
+        order.setSize(n);
+    }
+}
+
+
 template<class T, class ListType>
 ListType Foam::subset
 (
diff --git a/src/OpenFOAM/containers/Lists/SortableList/SortableList.C b/src/OpenFOAM/containers/Lists/SortableList/SortableList.C
index cb6c1571d3..0ae74df8af 100644
--- a/src/OpenFOAM/containers/Lists/SortableList/SortableList.C
+++ b/src/OpenFOAM/containers/Lists/SortableList/SortableList.C
@@ -24,6 +24,23 @@ License
 
 \*---------------------------------------------------------------------------*/
 
+// * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * * //
+
+template <class Type>
+void Foam::SortableList<Type>::sortIndices(List<label>& ind) const
+{
+    // list lengths must be identical
+    ind.setSize(this->size());
+
+    forAll(ind, i)
+    {
+        ind[i] = i;
+    }
+
+    Foam::stableSort(ind, typename UList<Type>::less(*this));
+}
+
+
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
 template <class Type>
@@ -73,13 +90,6 @@ Foam::SortableList<Type>::SortableList(const SortableList<Type>& lst)
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
-template <class Type>
-void Foam::SortableList<Type>::setSize(const label newSize)
-{
-    List<Type>::setSize(newSize);
-    indices_.setSize(newSize, -1);
-}
-
 
 template <class Type>
 void Foam::SortableList<Type>::clear()
@@ -100,15 +110,7 @@ Foam::List<Type>& Foam::SortableList<Type>::shrink()
 template <class Type>
 void Foam::SortableList<Type>::sort()
 {
-    // list lengths must be identical
-    indices_.setSize(this->size());
-
-    forAll(indices_, i)
-    {
-        indices_[i] = i;
-    }
-
-    Foam::stableSort(indices_, typename UList<Type>::less(*this));
+    sortIndices(indices_);
 
     List<Type> lst(this->size());
     forAll(indices_, i)
@@ -120,10 +122,33 @@ void Foam::SortableList<Type>::sort()
 }
 
 
+template <class Type>
+void Foam::SortableList<Type>::reverseSort()
+{
+    sortIndices(indices_);
+
+    List<Type> lst(this->size());
+    label endI = indices_.size();
+    forAll(indices_, i)
+    {
+        lst[--endI] = this->operator[](indices_[i]);
+    }
+
+    List<Type>::transfer(lst);
+}
+
+
 // * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
 
 template <class Type>
-void Foam::SortableList<Type>::operator=(const UList<Type>& rhs)
+inline void Foam::SortableList<Type>::operator=(const Type& t)
+{
+    UList<Type>::operator=(t);
+}
+
+
+template <class Type>
+inline void Foam::SortableList<Type>::operator=(const UList<Type>& rhs)
 {
     List<Type>::operator=(rhs);
     indices_.clear();
@@ -131,7 +156,7 @@ void Foam::SortableList<Type>::operator=(const UList<Type>& rhs)
 
 
 template <class Type>
-void Foam::SortableList<Type>::operator=(const SortableList<Type>& rhs)
+inline void Foam::SortableList<Type>::operator=(const SortableList<Type>& rhs)
 {
     List<Type>::operator=(rhs);
     indices_ = rhs.indices();
diff --git a/src/OpenFOAM/containers/Lists/SortableList/SortableList.H b/src/OpenFOAM/containers/Lists/SortableList/SortableList.H
index 01cdce3780..40dc6dd68c 100644
--- a/src/OpenFOAM/containers/Lists/SortableList/SortableList.H
+++ b/src/OpenFOAM/containers/Lists/SortableList/SortableList.H
@@ -60,6 +60,9 @@ class SortableList
         //- Original indices
         labelList indices_;
 
+        //- Resize and sort the parameter according to the list values
+        void sortIndices(List<label>&) const;
+
 public:
 
     // Constructors
@@ -99,9 +102,6 @@ public:
             return indices_;
         }
 
-        //- Size the list. Growing can cause undefined indices (until next sort)
-        void setSize(const label);
-
         //- Clear the list and the indices
         void clear();
 
@@ -112,13 +112,19 @@ public:
         //  also resizes the indices as required
         void sort();
 
+        //- Reverse (stable) sort the list
+        void reverseSort();
+
     // Member Operators
 
+        //- Assignment of all entries to the given value
+        inline void operator=(const Type&);
+
         //- Assignment from UList operator. Takes linear time.
-        void operator=(const UList<Type>&);
+        inline void operator=(const UList<Type>&);
 
         //- Assignment operator. Takes linear time.
-        void operator=(const SortableList<Type>&);
+        inline void operator=(const SortableList<Type>&);
 
 };