diff --git a/setup.py b/setup.py
index 46e44fd58..744b46547 100644
--- a/setup.py
+++ b/setup.py
@@ -805,11 +805,13 @@ for pi in dbpi_dirs:
     mod_name = "_" + os.path.split(os.path.split(pi)[-2])[-1] + "_dbpi"
 
     pi_sources = glob.glob(os.path.join(pi, "*.cc"))
+    pi_sources += glob.glob(os.path.join(pi, "contrib", "*.cc"))
 
     pi_ext = Library(
         config.root + ".db_plugins." + mod_name,
         define_macros=config.macros() + [("MAKE_DB_PLUGIN_LIBRARY", 1)],
         include_dirs=[
+            pi,
             os.path.join("src", "plugins", "common"),
             _db_path,
             _tl_path,
diff --git a/src/buddies/src/bd/strmcmp.cc b/src/buddies/src/bd/strmcmp.cc
index 637baaab0..aefcefe6f 100644
--- a/src/buddies/src/bd/strmcmp.cc
+++ b/src/buddies/src/bd/strmcmp.cc
@@ -41,6 +41,7 @@ BD_PUBLIC int strmcmp (int argc, char *argv[])
   std::string infile_a, infile_b;
   std::string top_a, top_b;
   bool silent = false;
+  bool ignore_duplicates = false;
   bool no_text_orientation = true;
   bool no_text_details = true;
   bool no_properties = false;
@@ -106,6 +107,10 @@ BD_PUBLIC int strmcmp (int argc, char *argv[])
       << tl::arg ("--expand-arrays",           &flatten_array_insts, "Expands array instances before compare",
                   "With this option, arrays are equivalent single instances are treated identical."
                  )
+      << tl::arg ("-1|--ignore-duplicates",    &ignore_duplicates, "Ignore duplicate instances and shapes",
+                  "With this option, duplicate instances or shapes are ignored and duplication "
+                  "does not count as a difference."
+                 )
       << tl::arg ("-l|--layer-details",        &dont_summarize_missing_layers, "Prints details about differences for missing layers",
                   "With this option, missing layers are treated as \"empty\" and details about differences to "
                   "other, non-empty layers are printed. Essentially the content of the non-empty counterpart "
@@ -155,6 +160,9 @@ BD_PUBLIC int strmcmp (int argc, char *argv[])
   if (silent) {
     flags |= db::layout_diff::f_silent;
   }
+  if (ignore_duplicates) {
+    flags |= db::layout_diff::f_ignore_duplicates;
+  }
   if (no_text_orientation) {
     flags |= db::layout_diff::f_no_text_orientation;
   }
diff --git a/src/db/db/dbBoxScanner.h b/src/db/db/dbBoxScanner.h
index 5b562bee2..d329316f4 100644
--- a/src/db/db/dbBoxScanner.h
+++ b/src/db/db/dbBoxScanner.h
@@ -538,7 +538,7 @@ public:
    *  @brief Default ctor
    */
   box_scanner2 (bool report_progress = false, const std::string &progress_desc = std::string ())
-    : m_fill_factor (2), m_scanner_thr (100),
+    : m_fill_factor (2), m_scanner_thr (100), m_scanner_thr1 (10),
       m_report_progress (report_progress), m_progress_desc (progress_desc)
   {
     //  .. nothing yet ..
@@ -564,6 +564,26 @@ public:
     return m_scanner_thr;
   }
 
+  /**
+   *  @brief Sets the scanner threshold per class
+   *
+   *  This value determines for how many elements in one class the implementation switches to the scanner
+   *  implementation instead of the plain element-by-element interaction test.
+   *  The default value is 10.
+   */
+  void set_scanner_threshold1 (size_t n)
+  {
+    m_scanner_thr1 = n;
+  }
+
+  /**
+   *  @brief Gets the scanner threshold per class
+   */
+  size_t scanner_threshold1 () const
+  {
+    return m_scanner_thr1;
+  }
+
   /**
    *  @brief Sets the fill factor
    *
@@ -667,7 +687,7 @@ private:
   container_type1 m_pp1;
   container_type2 m_pp2;
   double m_fill_factor;
-  size_t m_scanner_thr;
+  size_t m_scanner_thr, m_scanner_thr1;
   bool m_report_progress;
   std::string m_progress_desc;
 
@@ -732,7 +752,7 @@ private:
         rec.finish2 (i->first, i->second);
       }
 
-    } else if (m_pp1.size () + m_pp2.size () <= m_scanner_thr) {
+    } else if (m_pp1.size () + m_pp2.size () <= m_scanner_thr || m_pp2.size () <= m_scanner_thr1 || m_pp1.size () <= m_scanner_thr1) {
 
       //  below m_scanner_thr elements use the brute force approach which is faster in that case
 
diff --git a/src/db/db/dbCell.cc b/src/db/db/dbCell.cc
index 64efb2aaf..83acc1182 100644
--- a/src/db/db/dbCell.cc
+++ b/src/db/db/dbCell.cc
@@ -187,6 +187,17 @@ Cell::clear (unsigned int index)
   }
 }
 
+void
+Cell::clear (unsigned int index, unsigned int types)
+{
+  shapes_map::iterator s = m_shapes_map.find(index);
+  if (s != m_shapes_map.end() && ! s->second.empty ()) {
+    mp_layout->invalidate_bboxes (index);  //  HINT: must come before the change is done!
+    s->second.clear (types);
+    m_bbox_needs_update = true;
+  }
+}
+
 Cell::shapes_type &
 Cell::shapes (unsigned int index) 
 {
@@ -344,6 +355,20 @@ Cell::copy (unsigned int src, unsigned int dest)
   }
 }
 
+void
+Cell::copy (unsigned int src, unsigned int dest, unsigned int types)
+{
+  if (src != dest) {
+    shapes (dest).insert (shapes (src), types);
+  } else {
+    //  When duplicating the layer, first create a copy to avoid problems with non-stable containers
+    //  Hint: using the assignment and not the copy ctor does not copy the db::Manager association.
+    db::Shapes shape_copy;
+    shape_copy.insert (shapes (src), types);
+    shapes (dest).insert (shape_copy);
+  }
+}
+
 void
 Cell::move (unsigned int src, unsigned int dest)
 {
@@ -353,6 +378,15 @@ Cell::move (unsigned int src, unsigned int dest)
   }
 }
 
+void
+Cell::move (unsigned int src, unsigned int dest, unsigned int types)
+{
+  if (src != dest) {
+    copy (src, dest, types);
+    clear (src, types);
+  }
+}
+
 void
 Cell::swap (unsigned int i1, unsigned int i2)
 {
diff --git a/src/db/db/dbCell.h b/src/db/db/dbCell.h
index 00319ee08..2d04bc0ba 100644
--- a/src/db/db/dbCell.h
+++ b/src/db/db/dbCell.h
@@ -182,6 +182,13 @@ public:
    */
   void copy (unsigned int src, unsigned int dest);
 
+  /**
+   *  @brief Copy the shapes from layer src to dest (only shapes from given classes)
+   *
+   *  The target layer is not overwritten. Instead, the shapes are added to the target layer's shapes.
+   */
+  void copy (unsigned int src, unsigned int dest, unsigned int types);
+
   /**
    *  @brief Move the shapes from layer src to dest
    *
@@ -189,6 +196,13 @@ public:
    */
   void move (unsigned int src, unsigned int dest);
 
+  /**
+   *  @brief Move the shapes from layer src to dest (only shapes from given classes)
+   *
+   *  The target layer is not overwritten. Instead, the shapes are added to the target layer's shapes.
+   */
+  void move (unsigned int src, unsigned int dest, unsigned int types);
+
   /**
    *  @brief Swap the layers given
    */
@@ -199,7 +213,12 @@ public:
    */
   void clear (unsigned int index);
 
-  /** 
+  /**
+   *  @brief Clear the shapes on the given layer (only the shapes from the given classes)
+   */
+  void clear (unsigned int index, unsigned int types);
+
+  /**
    *  @brief Erase a cell instance given by a instance proxy
    *
    *  Erasing a cell instance will destroy the sorting order and invalidate
diff --git a/src/db/db/dbDeepRegion.cc b/src/db/db/dbDeepRegion.cc
index 0d7d725de..bed425c3d 100644
--- a/src/db/db/dbDeepRegion.cc
+++ b/src/db/db/dbDeepRegion.cc
@@ -962,10 +962,31 @@ DeepRegion::xor_with (const Region &other, db::PropertyConstraint property_const
 
     //  Implement XOR as (A-B)+(B-A) - only this implementation
     //  is compatible with the local processor scheme
-    DeepLayer n1 (and_or_not_with (other_deep, false, property_constraint));
-    DeepLayer n2 (other_deep->and_or_not_with (this, false, property_constraint));
 
+    //  Prepare a version of "other_deep" that is mapped into the hierarchy space
+    //  of "this"
+    std::unique_ptr<DeepRegion> other_deep_mapped;
+    if (&other_deep->deep_layer ().layout () == &deep_layer ().layout ()) {
+      //  shallow copy for reconfiguration (progress etc.)
+      other_deep_mapped.reset (new DeepRegion (other_deep->deep_layer ()));
+    } else {
+      //  deep copy with mapped hierarchy
+      other_deep_mapped.reset (new DeepRegion (deep_layer ().derived ()));
+      other_deep_mapped->deep_layer ().add_from (other_deep->deep_layer ());
+    }
+
+    other_deep_mapped->set_strict_handling (strict_handling ());
+    other_deep_mapped->set_base_verbosity (base_verbosity ());
+    if (report_progress ()) {
+      other_deep_mapped->enable_progress (progress_desc () + tl::to_string (tr (" - reverse part")));
+    } else {
+      other_deep_mapped->disable_progress ();
+    }
+
+    DeepLayer n1 (and_or_not_with (other_deep_mapped.get (), false, property_constraint));
+    DeepLayer n2 (other_deep_mapped->and_or_not_with (this, false, property_constraint));
     n1.add_from (n2);
+
     return new DeepRegion (n1);
 
   }
diff --git a/src/db/db/dbHierProcessor.cc b/src/db/db/dbHierProcessor.cc
index e69057b84..9987451e2 100644
--- a/src/db/db/dbHierProcessor.cc
+++ b/src/db/db/dbHierProcessor.cc
@@ -64,6 +64,11 @@ cronology::events::event_collection<event_compute_results, event_compute_local_c
 namespace db
 {
 
+//  Heuristic parameter to control the recursion of the cell-to-cell intruder
+//  detection: do not recurse if the intruder cell's bounding box is smaller
+//  than the overlap box times this factor.
+const double area_ratio_for_recursion = 3.0;
+
 // ---------------------------------------------------------------------------------------------
 //  Shape reference translator
 
@@ -370,6 +375,32 @@ db::Box safe_box_enlarged (const db::Box &box, db::Coord dx, db::Coord dy)
   }
 }
 
+// ---------------------------------------------------------------------------------------------
+//  Debugging utility: dump the cell contexts
+
+template <class TS, class TI, class TR>
+static void dump_cell_contexts (local_processor_contexts<TS, TI, TR> &contexts, const db::Layout *subject_layout, const db::Layout *intruder_layout)
+{
+  for (auto cc = contexts.begin (); cc != contexts.end (); ++cc) {
+    tl::info << "Cell " << subject_layout->cell_name (cc->first->cell_index ()) << ":";
+    int i = 0;
+    for (auto c = cc->second.begin (); c != cc->second.end (); ++c) {
+      tl::info << "  Context #" << ++i;
+      tl::info << "    Instances:";
+      for (auto i = c->first.first.begin (); i != c->first.first.end (); ++i) {
+        const db::CellInstArray &ci = *i;
+        tl::info << "      " << intruder_layout->cell_name (ci.object ().cell_index ()) << " @ " << ci.complex_trans (*ci.begin ()).to_string () << " (" << ci.size () << ")";
+      }
+      tl::info << "    Shapes:";
+      for (auto i = c->first.second.begin (); i != c->first.second.end (); ++i) {
+        for (auto s = i->second.begin (); s != i->second.end (); ++s) {
+          tl::info << "      " << intruder_layout->get_properties (i->first).to_string () << ": " << s->to_string ();
+        }
+      }
+    }
+  }
+}
+
 // ---------------------------------------------------------------------------------------------
 //  LocalProcessorCellContext implementation
 
@@ -1208,7 +1239,8 @@ private:
   void
   collect_instance_interactions (const db::CellInstArray *inst1, const db::CellInstArray *inst2)
   {
-    //  TODO: this algorithm is not in particular effective for identical arrays
+    //  TODO: this algorithm is not in particular effective for identical arrays or for arrays
+    //  vs. single instances
 
     const db::Cell &cell1 = mp_subject_layout->cell (inst1->object ().cell_index ());
     const db::Cell &cell2 = mp_intruder_layout->cell (inst2->object ().cell_index ());
@@ -1247,7 +1279,7 @@ private:
           db::Box ibox2 = tn2 * cell2.bbox (m_intruder_layer).enlarged (db::Vector (m_dist, m_dist));
 
           db::Box cbox = ibox1 & ibox2;
-          if (! cbox.empty () && cell1.has_shapes_touching (m_subject_layer, safe_box_enlarged (tni1 * cbox, -1, -1))) {
+          if (! cbox.empty () && (cbox == ibox1 || cell1.has_shapes_touching (m_subject_layer, safe_box_enlarged (tni1 * cbox, -1, -1)))) {
 
             db::ICplxTrans tn21 = tni1 * tn2;
 
@@ -1282,9 +1314,11 @@ private:
     db::ICplxTrans tni2 = tn21.inverted () * tni1;
     db::Box tbox2 = safe_box_enlarged (tni2 * cbox, -1, -1);
 
-    if (! intruder_cell.shapes (m_intruder_layer).begin_touching (tbox2, ShapeIterator::All).at_end ()) {
+    //  do not recurse further if we're overlapping with shapes from the intruder
+    //  or the intruder cell is not much bigger than the region of interest (cbox)
+    if (intruder_cell.bbox (m_intruder_layer).area () < area_ratio_for_recursion * cbox.area ()
+        || ! intruder_cell.shapes (m_intruder_layer).begin_touching (tbox2, ShapeIterator::All).at_end ()) {
 
-      //  we're overlapping with shapes from the intruder - do not recursive further
       interactions.push_back (std::make_pair (intruder_cell.cell_index (), tn21));
       return;
 
@@ -1782,6 +1816,11 @@ template <class TS, class TI, class TR>
 void
 local_processor<TS, TI, TR>::compute_results (local_processor_contexts<TS, TI, TR> &contexts, const local_operation<TS, TI, TR> *op, const std::vector<unsigned int> &output_layers) const
 {
+#if 0
+  //  debugging
+  dump_cell_contexts (contexts, mp_subject_layout, mp_intruder_layout ? mp_intruder_layout : mp_subject_layout);
+#endif
+
   tl::SelfTimer timer (tl::verbosity () > m_base_verbosity + 10, tl::to_string (tr ("Computing results for ")) + description (op));
 
   //  avoids updates while we work on the layout
diff --git a/src/db/db/dbLayout.cc b/src/db/db/dbLayout.cc
index 0b53b70a1..32bba3042 100644
--- a/src/db/db/dbLayout.cc
+++ b/src/db/db/dbLayout.cc
@@ -1971,7 +1971,19 @@ Layout::move_layer (unsigned int src, unsigned int dest)
   }
 }
 
-void 
+void
+Layout::move_layer (unsigned int src, unsigned int dest, unsigned int flags)
+{
+  tl_assert (m_layers.layer_state (src) != LayoutLayers::Free);
+  tl_assert (m_layers.layer_state (dest) != LayoutLayers::Free);
+
+  //  move the shapes
+  for (iterator c = begin (); c != end (); ++c) {
+    c->move (src, dest, flags);
+  }
+}
+
+void
 Layout::copy_layer (unsigned int src, unsigned int dest)
 {
   tl_assert (m_layers.layer_state (src) != LayoutLayers::Free);
@@ -1983,7 +1995,19 @@ Layout::copy_layer (unsigned int src, unsigned int dest)
   }
 }
 
-void 
+void
+Layout::copy_layer (unsigned int src, unsigned int dest, unsigned int flags)
+{
+  tl_assert (m_layers.layer_state (src) != LayoutLayers::Free);
+  tl_assert (m_layers.layer_state (dest) != LayoutLayers::Free);
+
+  //  copy the shapes
+  for (iterator c = begin (); c != end (); ++c) {
+    c->copy (src, dest, flags);
+  }
+}
+
+void
 Layout::clear_layer (unsigned int n)
 {
   tl_assert (m_layers.layer_state (n) != LayoutLayers::Free);
@@ -1994,7 +2018,18 @@ Layout::clear_layer (unsigned int n)
   }
 }
 
-void 
+void
+Layout::clear_layer (unsigned int n, unsigned int flags)
+{
+  tl_assert (m_layers.layer_state (n) != LayoutLayers::Free);
+
+  //  clear the shapes
+  for (iterator c = begin (); c != end (); ++c) {
+    c->clear (n, flags);
+  }
+}
+
+void
 Layout::delete_layer (unsigned int n)
 {
   tl_assert (m_layers.layer_state (n) != LayoutLayers::Free);
diff --git a/src/db/db/dbLayout.h b/src/db/db/dbLayout.h
index cb79d2a8a..353ad2ad9 100644
--- a/src/db/db/dbLayout.h
+++ b/src/db/db/dbLayout.h
@@ -1377,7 +1377,15 @@ public:
    */
   void move_layer (unsigned int src, unsigned int dest);
 
-  /**  
+  /**
+   *  @brief Move a layer (selected shape types only)
+   *
+   *  Move a layer from the source to the target. The target is not cleared before, so that this method
+   *  merges shapes from the source with the target layer. The source layer is empty after that operation.
+   */
+  void move_layer (unsigned int src, unsigned int dest, unsigned int flags);
+
+  /**
    *  @brief Copy a layer
    *
    *  Copy a layer from the source to the target. The target is not cleared before, so that this method 
@@ -1385,14 +1393,29 @@ public:
    */
   void copy_layer (unsigned int src, unsigned int dest);
 
-  /**  
+  /**
+   *  @brief Copy a layer (selected shape types only)
+   *
+   *  Copy a layer from the source to the target. The target is not cleared before, so that this method
+   *  merges shapes from the source with the target layer.
+   */
+  void copy_layer (unsigned int src, unsigned int dest, unsigned int flags);
+
+  /**
    *  @brief Clear a layer
    *
    *  Clears the layer: removes all shapes.
    */
   void clear_layer (unsigned int n);
 
-  /**  
+  /**
+   *  @brief Clear a layer (selected shapes only)
+   *
+   *  Clears the layer: removes the shapes of the type given the flags (ShapeIterator::shapes_type)
+   */
+  void clear_layer (unsigned int n, unsigned int flags);
+
+  /**
    *  @brief Delete a layer
    *
    *  This does free the shapes of the cells and remembers the
diff --git a/src/db/db/dbLayoutDiff.cc b/src/db/db/dbLayoutDiff.cc
index d52ec900e..be1e005e7 100644
--- a/src/db/db/dbLayoutDiff.cc
+++ b/src/db/db/dbLayoutDiff.cc
@@ -69,8 +69,10 @@ collect_cells (const db::Layout &l, const db::Cell *top, std::map <std::string,
 }
 
 static void
-collect_insts_of_unmapped_cells (const db::Layout & /*l*/, const db::Cell *cell, unsigned int /*flags*/, const std::map <db::cell_index_type, db::cell_index_type> &cci, std::vector <db::CellInstArrayWithProperties> &insts)
+collect_insts_of_unmapped_cells (const db::Layout & /*l*/, const db::Cell *cell, unsigned int /*flags*/, const std::map <db::cell_index_type, db::cell_index_type> &cci, std::vector <db::CellInstArrayWithProperties> &insts, bool no_duplicates)
 {
+  size_t n_before = insts.size ();
+
   for (db::Cell::const_iterator i = cell->begin (); !i.at_end (); ++i) {
 
     std::map <db::cell_index_type, db::cell_index_type>::const_iterator ccii = cci.find (i->cell_index ());
@@ -81,6 +83,13 @@ collect_insts_of_unmapped_cells (const db::Layout & /*l*/, const db::Cell *cell,
 
     }
   }
+
+  if (no_duplicates) {
+
+    std::sort (insts.begin () + n_before, insts.end ());
+    insts.erase (std::unique (insts.begin () + n_before, insts.end ()), insts.end ());
+
+  }
 }
 
 static void 
@@ -102,7 +111,7 @@ rewrite_instances_to (std::vector <db::CellInstArrayWithProperties> &insts, unsi
 }
 
 static void
-collect_insts (const db::Layout & /*l*/, const db::Cell *cell, unsigned int flags, const std::map <db::cell_index_type, db::cell_index_type> &cci, std::vector <db::CellInstArrayWithProperties> &insts, PropertyMapper &pn)
+collect_insts (const db::Layout & /*l*/, const db::Cell *cell, unsigned int flags, const std::map <db::cell_index_type, db::cell_index_type> &cci, std::vector <db::CellInstArrayWithProperties> &insts, PropertyMapper &pn, bool no_duplicates)
 {
   insts.clear ();
 
@@ -148,6 +157,10 @@ collect_insts (const db::Layout & /*l*/, const db::Cell *cell, unsigned int flag
   }
 
   std::sort (insts.begin (), insts.end ());
+
+  if (no_duplicates) {
+    insts.erase (std::unique (insts.begin (), insts.end ()), insts.end ());
+  }
 }
 
 /**
@@ -178,10 +191,10 @@ int compare_seq (I b1, I e1, I b2, I e2, Op op)
 /**
  *  @brief Reduces two vectors to the common objects as determined by the compare operator
  *  If the iterate parameter is true, the reduction is repeated until no more reduction can be 
- *  achieved. This is useful with tolerances since the sorted is not strict in that case.
+ *  achieved. This is useful with tolerances since the sorting is not strict in that case.
  */
 template <class X, class Op>
-void reduce (std::vector<X> &a, std::vector<X> &b, Op op, bool iterate)
+void reduce (std::vector<X> &a, std::vector<X> &b, Op op, bool iterate, bool no_duplicates)
 {
   do {
 
@@ -196,12 +209,29 @@ void reduce (std::vector<X> &a, std::vector<X> &b, Op op, bool iterate)
 
     while (ra != a.end () && rb != b.end ()) {
       if (op (*ra, *rb)) {
-        *wa++ = *ra++;
+        typename std::vector<X>::const_iterator r = ra++;
+        *wa = *r;
+        while (no_duplicates && ra != a.end () && !op (*ra, *r) && !op(*r, *ra)) {
+          ++ra;
+        }
+        ++wa;
       } else if (op (*rb, *ra)) {
-        *wb++ = *rb++;
+        typename std::vector<X>::const_iterator r = rb++;
+        *wb = *r;
+        while (no_duplicates && rb != b.end () && !op (*rb, *r) && !op(*r, *rb)) {
+          ++rb;
+        }
+        ++wb;
       } else {
-        ++ra;
-        ++rb;
+        typename std::vector<X>::const_iterator r;
+        r = ra++;
+        while (no_duplicates && ra != a.end () && !op (*ra, *r) && !op(*r, *ra)) {
+          ++ra;
+        }
+        r = rb++;
+        while (no_duplicates && rb != b.end () && !op (*rb, *r) && !op(*r, *rb)) {
+          ++rb;
+        }
       }
     }
 
@@ -211,14 +241,22 @@ void reduce (std::vector<X> &a, std::vector<X> &b, Op op, bool iterate)
 
     if (ra != wa) {
       while (ra != a.end ()) {
-        *wa++ = *ra++;
+        typename std::vector<X>::const_iterator r = ra++;
+        *wa++ = *r;
+        while (no_duplicates && ra != a.end () && !op (*ra, *r) && !op(*r, *ra)) {
+          ++ra;
+        }
       }
       a.erase (wa, a.end ());
     }
 
     if (rb != wb) {
       while (rb != b.end ()) {
-        *wb++ = *rb++;
+        typename std::vector<X>::const_iterator r = rb++;
+        *wb++ = *r;
+        while (no_duplicates && rb != b.end () && !op (*rb, *r) && !op(*r, *rb)) {
+          ++rb;
+        }
       }
       b.erase (wb, b.end ());
     }
@@ -405,7 +443,7 @@ struct PolygonCompareOpWithTolerance
       m_eb.push_back (*e);
     }
 
-    reduce (m_ea, m_eb, EdgeCompareOpWithTolerance (m_tolerance), m_tolerance > 0);
+    reduce (m_ea, m_eb, EdgeCompareOpWithTolerance (m_tolerance), m_tolerance > 0, false);
 
     return compare_seq (m_ea.begin (), m_ea.end (), m_eb.begin (), m_eb.end (), EdgeCompareOpWithTolerance (m_tolerance)) < 0;
   }
@@ -665,6 +703,7 @@ do_compare_layouts (const db::Layout &a, const db::Cell *top_a, const db::Layout
   }
 
   bool verbose = (flags & layout_diff::f_verbose);
+  bool no_duplicates = (flags & layout_diff::f_ignore_duplicates);
 
   db::Layout n, na, nb;
   na.properties_repository () = a.properties_repository ();
@@ -897,20 +936,20 @@ do_compare_layouts (const db::Layout &a, const db::Cell *top_a, const db::Layout
       r.bbox_differs (cell_a->bbox (), cell_b->bbox ());
     }
 
-    collect_insts (a, cell_a, flags, common_cell_indices_a, insts_a, prop_normalize_a);
-    collect_insts (b, cell_b, flags, common_cell_indices_b, insts_b, prop_normalize_b);
+    collect_insts (a, cell_a, flags, common_cell_indices_a, insts_a, prop_normalize_a, no_duplicates);
+    collect_insts (b, cell_b, flags, common_cell_indices_b, insts_b, prop_normalize_b, no_duplicates);
 
     std::vector <db::CellInstArrayWithProperties> anotb;
     std::set_difference (insts_a.begin (), insts_a.end (), insts_b.begin (), insts_b.end (), std::back_inserter (anotb));
 
     rewrite_instances_to (anotb, flags, common_cells_a, prop_remap_to_a);
-    collect_insts_of_unmapped_cells (a, cell_a, flags, common_cell_indices_a, anotb);
+    collect_insts_of_unmapped_cells (a, cell_a, flags, common_cell_indices_a, anotb, no_duplicates);
 
     std::vector <db::CellInstArrayWithProperties> bnota;
     std::set_difference (insts_b.begin (), insts_b.end (), insts_a.begin (), insts_a.end (), std::back_inserter (bnota));
 
     rewrite_instances_to (bnota, flags, common_cells_b, prop_remap_to_b);
-    collect_insts_of_unmapped_cells (b, cell_b, flags, common_cell_indices_b, bnota);
+    collect_insts_of_unmapped_cells (b, cell_b, flags, common_cell_indices_b, bnota, no_duplicates);
 
     if (! anotb.empty () || ! bnota.empty ()) {
 
@@ -979,7 +1018,7 @@ do_compare_layouts (const db::Layout &a, const db::Cell *top_a, const db::Layout
         collect_polygons (b, cell_b, layer_b, flags, polygons_b, prop_normalize_b);
       }
 
-      reduce (polygons_a, polygons_b, make_polygon_compare_func (tolerance), tolerance > 0);
+      reduce (polygons_a, polygons_b, make_polygon_compare_func (tolerance), tolerance > 0, no_duplicates);
 
       if (!polygons_a.empty () || !polygons_b.empty ()) {
         differs = true;
@@ -1007,7 +1046,7 @@ do_compare_layouts (const db::Layout &a, const db::Cell *top_a, const db::Layout
           collect_paths (b, cell_b, layer_b, flags, paths_b, prop_normalize_b);
         }
 
-        reduce (paths_a, paths_b, make_path_compare_func (tolerance), tolerance > 0);
+        reduce (paths_a, paths_b, make_path_compare_func (tolerance), tolerance > 0, no_duplicates);
 
         if (!paths_a.empty () || !paths_b.empty ()) {
           differs = true;
@@ -1034,7 +1073,7 @@ do_compare_layouts (const db::Layout &a, const db::Cell *top_a, const db::Layout
         collect_texts (b, cell_b, layer_b, flags, texts_b, prop_normalize_b);
       }
 
-      reduce (texts_a, texts_b, make_text_compare_func (tolerance), tolerance > 0);
+      reduce (texts_a, texts_b, make_text_compare_func (tolerance), tolerance > 0, no_duplicates);
 
       if (!texts_a.empty () || !texts_b.empty ()) {
         differs = true;
@@ -1061,7 +1100,7 @@ do_compare_layouts (const db::Layout &a, const db::Cell *top_a, const db::Layout
           collect_boxes (b, cell_b, layer_b, flags, boxes_b, prop_normalize_b);
         }
 
-        reduce (boxes_a, boxes_b, make_box_compare_func (tolerance), tolerance > 0);
+        reduce (boxes_a, boxes_b, make_box_compare_func (tolerance), tolerance > 0, no_duplicates);
 
         if (!boxes_a.empty () || !boxes_b.empty ()) {
           differs = true;
@@ -1088,7 +1127,7 @@ do_compare_layouts (const db::Layout &a, const db::Cell *top_a, const db::Layout
         collect_edges (b, cell_b, layer_b, flags, edges_b, prop_normalize_b);
       }
 
-      reduce (edges_a, edges_b, make_edge_compare_func (tolerance), tolerance > 0);
+      reduce (edges_a, edges_b, make_edge_compare_func (tolerance), tolerance > 0, no_duplicates);
 
       if (!edges_a.empty () || !edges_b.empty ()) {
         differs = true;
@@ -1113,7 +1152,7 @@ do_compare_layouts (const db::Layout &a, const db::Cell *top_a, const db::Layout
         collect_edge_pairs (b, cell_b, layer_b, flags, edge_pairs_b, prop_normalize_b);
       }
 
-      reduce (edge_pairs_a, edge_pairs_b, make_edge_pair_compare_func (tolerance), tolerance > 0);
+      reduce (edge_pairs_a, edge_pairs_b, make_edge_pair_compare_func (tolerance), tolerance > 0, no_duplicates);
 
       if (!edge_pairs_a.empty () || !edge_pairs_b.empty ()) {
         differs = true;
diff --git a/src/db/db/dbLayoutDiff.h b/src/db/db/dbLayoutDiff.h
index 865883af1..56f0114b6 100644
--- a/src/db/db/dbLayoutDiff.h
+++ b/src/db/db/dbLayoutDiff.h
@@ -74,12 +74,15 @@ const unsigned int f_paths_as_polygons = 0x100;
 //  Derive smart cell mapping instead of name mapping (available only if top cells are specified)
 const unsigned int f_smart_cell_mapping = 0x200;
 
-//  Don't summarize missing layers
+//  Don't summarize missing layers - print them in detail
 const unsigned int f_dont_summarize_missing_layers = 0x400;
 
 //  Ignore text details (font, size, presentation)
 const unsigned int f_no_text_details = 0x800;
 
+//  Ignore duplicate instances or shapes
+const unsigned int f_ignore_duplicates = 0x1000;
+
 }
 
 /**
diff --git a/src/db/db/dbShapes.cc b/src/db/db/dbShapes.cc
index d8b439404..48736115d 100644
--- a/src/db/db/dbShapes.cc
+++ b/src/db/db/dbShapes.cc
@@ -81,6 +81,12 @@ inline bool needs_translate (object_tag<Sh> /*tag*/)
   return tl::is_equal_type<typename shape_traits<Sh>::can_deref, tl::True> () || tl::is_equal_type<typename shape_traits<Sh>::is_array, tl::True> ();
 }
 
+inline bool type_mask_applies (const db::LayerBase *layer, unsigned int flags)
+{
+  unsigned int tm = layer->type_mask ();
+  return (((flags & db::ShapeIterator::Properties) == 0 || (tm & db::ShapeIterator::Properties) != 0) && (flags & tm) != 0);
+}
+
 // ---------------------------------------------------------------------------------------
 //  layer_op implementation
 
@@ -214,7 +220,13 @@ Shapes::insert (const Shapes &d)
 }
 
 void
-Shapes::do_insert (const Shapes &d)
+Shapes::insert (const Shapes &d, unsigned int flags)
+{
+  do_insert (d, flags);
+}
+
+void
+Shapes::do_insert (const Shapes &d, unsigned int flags)
 {
   //  shortcut for "nothing to do"
   if (d.empty ()) {
@@ -228,10 +240,12 @@ Shapes::do_insert (const Shapes &d)
 
       m_layers.reserve (d.m_layers.size ());
       for (tl::vector<LayerBase *>::const_iterator l = d.m_layers.begin (); l != d.m_layers.end (); ++l) {
-        m_layers.push_back ((*l)->clone ());
-        if (manager () && manager ()->transacting ()) {
-          check_is_editable_for_undo_redo ();
-          manager ()->queue (this, new FullLayerOp (true, m_layers.back ()));
+        if (type_mask_applies (*l, flags)) {
+          m_layers.push_back ((*l)->clone ());
+          if (manager () && manager ()->transacting ()) {
+            check_is_editable_for_undo_redo ();
+            manager ()->queue (this, new FullLayerOp (true, m_layers.back ()));
+          }
         }
       }
 
@@ -239,7 +253,9 @@ Shapes::do_insert (const Shapes &d)
 
     } else {
       for (tl::vector<LayerBase *>::const_iterator l = d.m_layers.begin (); l != d.m_layers.end (); ++l) {
-        (*l)->insert_into (this);
+        if (type_mask_applies (*l, flags)) {
+          (*l)->insert_into (this);
+        }
       }
     }
 
@@ -247,14 +263,18 @@ Shapes::do_insert (const Shapes &d)
 
     //  the target is standalone - dereference
     for (tl::vector<LayerBase *>::const_iterator l = d.m_layers.begin (); l != d.m_layers.end (); ++l) {
-      (*l)->deref_into (this);
+      if (type_mask_applies (*l, flags)) {
+        (*l)->deref_into (this);
+      }
     }
 
   } else {
 
     //  both shape containers are in separate spaces - translate
     for (tl::vector<LayerBase *>::const_iterator l = d.m_layers.begin (); l != d.m_layers.end (); ++l) {
-      (*l)->translate_into (this, shape_repository (), array_repository ());
+      if (type_mask_applies (*l, flags)) {
+        (*l)->translate_into (this, shape_repository (), array_repository ());
+      }
     }
 
   }
@@ -1046,6 +1066,41 @@ Shapes::clear ()
   }
 }
 
+void
+Shapes::clear (unsigned int flags)
+{
+  if (!m_layers.empty ()) {
+
+    invalidate_state ();  //  HINT: must come before the change is done!
+
+    tl::vector<LayerBase *> new_layers;
+
+    for (tl::vector<LayerBase *>::const_iterator l = m_layers.end (); l != m_layers.begin (); ) {
+
+      //  because the undo stack will do a push, we need to remove layers from the back (this is the last undo
+      //  element to be executed)
+      --l;
+
+      if (type_mask_applies (*l, flags)) {
+
+        if (manager () && manager ()->transacting ()) {
+          check_is_editable_for_undo_redo ();
+          manager ()->queue (this, new FullLayerOp (false, (*l)));
+        } else {
+          delete *l;
+        }
+
+      } else {
+        new_layers.push_back (*l);
+      }
+
+    }
+
+    m_layers.swap (new_layers);
+
+  }
+}
+
 void Shapes::reset_bbox_dirty ()
 {
   set_dirty (false);
diff --git a/src/db/db/dbShapes.h b/src/db/db/dbShapes.h
index b8114e360..bffb08315 100644
--- a/src/db/db/dbShapes.h
+++ b/src/db/db/dbShapes.h
@@ -628,6 +628,18 @@ public:
    */
   void insert (const Shapes &d);
 
+  /**
+   *  @brief Insert all shapes from another container using the given shape types only
+   *
+   *  This method insert all shapes from the given shape container.
+   *
+   *  HINT: This method can duplicate shape containers from one layout to another.
+   *  The current implementation does not translate property Id's.
+   *  It is mainly intended for 1-to-1 copies of layouts where the whole
+   *  property repository is copied.
+   */
+  void insert (const Shapes &d, unsigned int types);
+
   /**
    *  @brief Assignment operator with transformation
    *
@@ -1219,6 +1231,11 @@ public:
    */
   void clear ();
 
+  /**
+   *  @brief Clears the collection (given shape types only)
+   */
+  void clear (unsigned int types);
+
   /**
    *  @brief Report the type mask of the objects stored herein
    *
@@ -1515,7 +1532,7 @@ private:
   db::Cell *mp_cell;  //  HINT: contains "dirty" in bit 0 and "editable" in bit 1
 
   void invalidate_state ();
-  void do_insert (const Shapes &d);
+  void do_insert (const Shapes &d, unsigned int flags = db::ShapeIterator::All);
   void check_is_editable_for_undo_redo () const;
 
   //  gets the layers array
diff --git a/src/db/db/gsiDeclDbLayout.cc b/src/db/db/gsiDeclDbLayout.cc
index 8285bc5fa..9da66889d 100644
--- a/src/db/db/gsiDeclDbLayout.cc
+++ b/src/db/db/gsiDeclDbLayout.cc
@@ -1682,29 +1682,53 @@ Class<db::Layout> decl_Layout ("db", "Layout",
     "@param a The first of the layers to swap.\n"
     "@param b The second of the layers to swap.\n"
   ) +
-  gsi::method ("move_layer", &db::Layout::move_layer, gsi::arg ("src"), gsi::arg ("dest"),
+  gsi::method ("move_layer", static_cast<void (db::Layout::*) (unsigned int, unsigned int)> (&db::Layout::move_layer), gsi::arg ("src"), gsi::arg ("dest"),
     "@brief Moves a layer\n"
     "\n"
-    "This method was introduced in version 0.19.\n"
-    "\n"
-    "Move a layer from the source to the target. The target is not cleared before, so that this method \n"
-    "merges shapes from the source with the target layer. The source layer is empty after that operation.\n"
+    "Moves a layer from the source to the destination layer. The target is not cleared before, so that this method \n"
+    "merges shapes from the source with the destination layer. The source layer is empty after that operation.\n"
     "\n"
     "@param src The layer index of the source layer.\n"
     "@param dest The layer index of the destination layer.\n"
+    "\n"
+    "This method was introduced in version 0.19.\n"
   ) +
-  gsi::method ("copy_layer", &db::Layout::copy_layer, gsi::arg ("src"), gsi::arg ("dest"),
+  gsi::method ("move_layer", static_cast<void (db::Layout::*) (unsigned int, unsigned int, unsigned int)> (&db::Layout::move_layer), gsi::arg ("src"), gsi::arg ("dest"), gsi::arg ("flags"),
+    "@brief Moves a layer (selected shape types only)\n"
+    "\n"
+    "Moves a layer from the source to the destination layer. The target is not cleared before, so that this method \n"
+    "merges shapes from the source with the destination layer. The copied shapes are removed from the source layer.\n"
+    "\n"
+    "@param src The layer index of the source layer.\n"
+    "@param dest The layer index of the destination layer.\n"
+    "@param flags A combination of the shape type flags from \\Shapes, S... constants\n"
+    "\n"
+    "This method variant has been introduced in version 0.28.9.\n"
+  ) +
+  gsi::method ("copy_layer", static_cast<void (db::Layout::*) (unsigned int, unsigned int)> (&db::Layout::copy_layer), gsi::arg ("src"), gsi::arg ("dest"),
     "@brief Copies a layer\n"
     "\n"
-    "This method was introduced in version 0.19.\n"
-    "\n"
-    "Copy a layer from the source to the target. The target is not cleared before, so that this method \n"
-    "merges shapes from the source with the target layer.\n"
+    "Copies a layer from the source to the destination layer. The destination layer is not cleared before, so that this method \n"
+    "merges shapes from the source with the destination layer.\n"
     "\n"
     "@param src The layer index of the source layer.\n"
     "@param dest The layer index of the destination layer.\n"
+    "\n"
+    "This method was introduced in version 0.19.\n"
   ) +
-  gsi::method ("clear_layer", &db::Layout::clear_layer, gsi::arg ("layer_index"),
+  gsi::method ("copy_layer", static_cast<void (db::Layout::*) (unsigned int, unsigned int, unsigned int)> (&db::Layout::copy_layer), gsi::arg ("src"), gsi::arg ("dest"), gsi::arg ("flags"),
+    "@brief Copies a layer (selected shape types only)\n"
+    "\n"
+    "Copies a layer from the source to the destination layer. The destination layer is not cleared before, so that this method \n"
+    "merges shapes from the source with the destination layer.\n"
+    "\n"
+    "@param src The layer index of the source layer.\n"
+    "@param dest The layer index of the destination layer.\n"
+    "@param flags A combination of the shape type flags from \\Shapes, S... constants\n"
+    "\n"
+    "This method variant has been introduced in version 0.28.9.\n"
+  ) +
+  gsi::method ("clear_layer", static_cast<void (db::Layout::*) (unsigned int)> (&db::Layout::clear_layer), gsi::arg ("layer_index"),
     "@brief Clears a layer\n"
     "\n"
     "Clears the layer: removes all shapes.\n"
@@ -1712,6 +1736,16 @@ Class<db::Layout> decl_Layout ("db", "Layout",
     "This method was introduced in version 0.19.\n"
     "\n"
     "@param layer_index The index of the layer to delete.\n"
+  ) +                               
+  gsi::method ("clear_layer", static_cast<void (db::Layout::*) (unsigned int, unsigned int)> (&db::Layout::clear_layer), gsi::arg ("layer_index"), gsi::arg ("flags"),
+    "@brief Clears a layer (given shape types only)\n"
+    "\n"
+    "Clears the layer: removes all shapes for the given shape types.\n"
+    "\n"
+    "This method was introduced in version 0.28.9.\n"
+    "\n"
+    "@param layer_index The index of the layer to delete.\n"
+    "@param flags The type selector for the shapes to delete (see \\Shapes class, S... constants).\n"
   ) +
   gsi::method ("delete_layer", &db::Layout::delete_layer, gsi::arg ("layer_index"),
     "@brief Deletes a layer\n"
diff --git a/src/db/db/gsiDeclDbLayoutDiff.cc b/src/db/db/gsiDeclDbLayoutDiff.cc
index 1d50c6857..1ed1335ca 100644
--- a/src/db/db/gsiDeclDbLayoutDiff.cc
+++ b/src/db/db/gsiDeclDbLayoutDiff.cc
@@ -397,6 +397,10 @@ static unsigned int f_silent () {
   return db::layout_diff::f_silent;
 }
 
+static unsigned int f_ignore_duplicates () {
+  return db::layout_diff::f_ignore_duplicates;
+}
+
 static unsigned int f_no_text_orientation () {
   return db::layout_diff::f_no_text_orientation;
 }
@@ -448,6 +452,13 @@ gsi::Class<LayoutDiff> decl_LayoutDiff ("db", "LayoutDiff",
     "This constant can be used for the flags parameter of \\compare_layouts and \\compare_cells. It can be "
     "compared with other constants to form a flag set."
   ) +
+  gsi::constant ("IgnoreDuplicates", &f_ignore_duplicates,
+    "@brief Ignore duplicate instances or shapes\n"
+    "With this option present, duplicate instances or shapes are ignored and "
+    "duplication does not count as a difference.\n"
+    "\n"
+    "This option has been introduced in version 0.28.9."
+  ) +
   gsi::constant ("NoTextOrientation", &f_no_text_orientation,
     "@brief Ignore text orientation\n"
     "This constant can be used for the flags parameter of \\compare_layouts and \\compare_cells. It can be "
diff --git a/src/db/db/gsiDeclDbShapes.cc b/src/db/db/gsiDeclDbShapes.cc
index e711fe0c6..33f1a90c5 100644
--- a/src/db/db/gsiDeclDbShapes.cc
+++ b/src/db/db/gsiDeclDbShapes.cc
@@ -108,47 +108,47 @@ static gsi::layout_locking_iterator1<db::Shapes::shape_iterator> begin (const db
   return gsi::layout_locking_iterator1<db::Shapes::shape_iterator> (s->layout (), s->begin (flags));
 }
 
-static gsi::layout_locking_iterator1<db::Shapes::shape_iterator>begin_all (const db::Shapes *s)
+static gsi::layout_locking_iterator1<db::Shapes::shape_iterator> begin_all (const db::Shapes *s)
 {
   return gsi::layout_locking_iterator1<db::Shapes::shape_iterator> (s->layout (), s->begin (db::ShapeIterator::All));
 }
 
-static gsi::layout_locking_iterator1<db::Shapes::shape_iterator>begin_overlapping (const db::Shapes *s, unsigned int flags, const db::Box &region)
+static gsi::layout_locking_iterator1<db::Shapes::shape_iterator> begin_overlapping (const db::Shapes *s, unsigned int flags, const db::Box &region)
 {
   return gsi::layout_locking_iterator1<db::Shapes::shape_iterator> (s->layout (), s->begin_overlapping (region, flags));
 }
 
-static gsi::layout_locking_iterator1<db::Shapes::shape_iterator>begin_doverlapping (const db::Shapes *s, unsigned int flags, const db::DBox &region)
+static gsi::layout_locking_iterator1<db::Shapes::shape_iterator> begin_doverlapping (const db::Shapes *s, unsigned int flags, const db::DBox &region)
 {
   return gsi::layout_locking_iterator1<db::Shapes::shape_iterator> (s->layout (), s->begin_overlapping (db::CplxTrans (shapes_dbu (s)).inverted () * region, flags));
 }
 
-static gsi::layout_locking_iterator1<db::Shapes::shape_iterator>begin_overlapping_all (const db::Shapes *s, const db::Box &region)
+static gsi::layout_locking_iterator1<db::Shapes::shape_iterator> begin_overlapping_all (const db::Shapes *s, const db::Box &region)
 {
   return gsi::layout_locking_iterator1<db::Shapes::shape_iterator> (s->layout (), s->begin_overlapping (region, db::ShapeIterator::All));
 }
 
-static gsi::layout_locking_iterator1<db::Shapes::shape_iterator>begin_doverlapping_all (const db::Shapes *s, const db::DBox &region)
+static gsi::layout_locking_iterator1<db::Shapes::shape_iterator> begin_doverlapping_all (const db::Shapes *s, const db::DBox &region)
 {
   return gsi::layout_locking_iterator1<db::Shapes::shape_iterator> (s->layout (), s->begin_overlapping (db::CplxTrans (shapes_dbu (s)).inverted () * region, db::ShapeIterator::All));
 }
 
-static gsi::layout_locking_iterator1<db::Shapes::shape_iterator>begin_touching (const db::Shapes *s, unsigned int flags, const db::Box &region)
+static gsi::layout_locking_iterator1<db::Shapes::shape_iterator> begin_touching (const db::Shapes *s, unsigned int flags, const db::Box &region)
 {
   return gsi::layout_locking_iterator1<db::Shapes::shape_iterator> (s->layout (), s->begin_touching (region, flags));
 }
 
-static gsi::layout_locking_iterator1<db::Shapes::shape_iterator>begin_dtouching (const db::Shapes *s, unsigned int flags, const db::DBox &region)
+static gsi::layout_locking_iterator1<db::Shapes::shape_iterator> begin_dtouching (const db::Shapes *s, unsigned int flags, const db::DBox &region)
 {
   return gsi::layout_locking_iterator1<db::Shapes::shape_iterator> (s->layout (), s->begin_touching (db::CplxTrans (shapes_dbu (s)).inverted () * region, flags));
 }
 
-static gsi::layout_locking_iterator1<db::Shapes::shape_iterator>begin_touching_all (const db::Shapes *s, const db::Box &region)
+static gsi::layout_locking_iterator1<db::Shapes::shape_iterator> begin_touching_all (const db::Shapes *s, const db::Box &region)
 {
   return gsi::layout_locking_iterator1<db::Shapes::shape_iterator> (s->layout (), s->begin_touching (region, db::ShapeIterator::All));
 }
 
-static gsi::layout_locking_iterator1<db::Shapes::shape_iterator>begin_dtouching_all (const db::Shapes *s, const db::DBox &region)
+static gsi::layout_locking_iterator1<db::Shapes::shape_iterator> begin_dtouching_all (const db::Shapes *s, const db::DBox &region)
 {
   return gsi::layout_locking_iterator1<db::Shapes::shape_iterator> (s->layout (), s->begin_touching (db::CplxTrans (shapes_dbu (s)).inverted () * region, db::ShapeIterator::All));
 }
@@ -251,12 +251,7 @@ static void insert_shapes (db::Shapes *sh, const db::Shapes &s)
 
 static void insert_shapes_with_flags (db::Shapes *sh, const db::Shapes &s, unsigned int flags)
 {
-  //  NOTE: if the source (r) is from the same layout than the shapes live in, we better
-  //  lock the layout against updates while inserting
-  db::LayoutLocker locker (sh->layout ());
-  for (db::Shapes::shape_iterator i = s.begin (flags); !i.at_end(); ++i) {
-    sh->insert (*i);
-  }
+  sh->insert (s, flags);
 }
 
 static void insert_shapes_with_trans (db::Shapes *sh, const db::Shapes &s, const db::ICplxTrans &trans)
@@ -1264,9 +1259,15 @@ Class<db::Shapes> decl_Shapes ("db", "Shapes",
     "@brief Returns a value indicating whether the shapes container is empty\n"
     "This method has been introduced in version 0.20.\n"
   ) +
-  gsi::method ("clear", &db::Shapes::clear, 
+  gsi::method ("clear", static_cast<void (db::Shapes::*) ()> (&db::Shapes::clear),
     "@brief Clears the shape container\n"
-    "This method has been introduced in version 0.16. It can only be used in editable mode."
+    "This method has been introduced in version 0.16."
+  ) +
+  gsi::method ("clear", static_cast<void (db::Shapes::*) (unsigned int)> (&db::Shapes::clear), gsi::arg ("flags"),
+    "@brief Clears certain shape types from the shape container\n"
+    "Only shapes matching the shape types from 'flags' are removed. 'flags' is a combination of the S... constants.\n"
+    "\n"
+    "This method has been introduced in version 0.28.9."
   ) +
   gsi::method_ext ("size", &shapes_size,
     "@brief Gets the number of shapes in this container\n"
@@ -1296,10 +1297,19 @@ Class<db::Shapes> decl_Shapes ("db", "Shapes",
     "returned for future references."
   ) +
   gsi::method ("SAll|#s_all", &s_all,
-    "@brief Indicates that all shapes shall be retrieved"
+    "@brief Indicates that all shapes shall be retrieved\n"
+    "You can use this constant to construct 'except' classes - e.g. "
+    "to specify 'all shape types except boxes' use\n"
+    "\n"
+    "@code SAll - SBoxes @/code\n"
   ) +
   gsi::method ("SAllWithProperties|#s_all_with_properties", &s_all_with_properties,
-    "@brief Indicates that all shapes with properties shall be retrieved"
+    "@brief Indicates that all shapes with properties shall be retrieved\n"
+    "Using this selector means to retrieve only shapes with properties."
+    "You can use this constant to construct 'except' classes - e.g. "
+    "to specify 'all shape types with properties except boxes' use\n"
+    "\n"
+    "@code SAllWithProperties - SBoxes @/code\n"
   ) +
   gsi::method ("SPolygons|#s_polygons", &s_polygons,
     "@brief Indicates that polygons shall be retrieved"
@@ -1333,7 +1343,10 @@ Class<db::Shapes> decl_Shapes ("db", "Shapes",
     "@brief Indicates that user objects shall be retrieved"
   ) +
   gsi::method ("SProperties|#s_properties", &s_properties,
-    "@brief Indicates that only shapes with properties shall be retrieved"
+    "@brief Indicates that only shapes with properties shall be retrieved\n"
+    "You can or-combine this flag with the plain shape types to select a "
+    "certain shape type, but only those shapes with properties. For example to "
+    "select boxes with properties, use 'SProperties | SBoxes'."
   ) +
   gsi::method_ext ("dump_mem_statistics", &dump_mem_statistics, gsi::arg<bool> ("detailed", false),
     "@hide"
diff --git a/src/db/unit_tests/dbBoxScannerTests.cc b/src/db/unit_tests/dbBoxScannerTests.cc
index 4d6de4959..9d772f340 100644
--- a/src/db/unit_tests/dbBoxScannerTests.cc
+++ b/src/db/unit_tests/dbBoxScannerTests.cc
@@ -938,6 +938,7 @@ TEST(two_1)
   db::box_convert<db::Box> bc1;
   db::box_convert<db::SimplePolygon> bc2;
   bs.set_scanner_threshold (0);
+  bs.set_scanner_threshold1 (0);
   bs.process (tr, 1, bc1, bc2);
   EXPECT_EQ (tr.str, "[i](2-12)(2-14)(4-12)(4-14)(2-15)(4-15)(5-12)(5-14)(5-15)(2-13)(4-13)(3-12)(3-14)(3-13)(3-15)(5-13)(0-10)<2><5><4><3><12><15><14><13>(0-11)(1-10)(1-11)<0><1><10><11>[f]");
 }
@@ -974,6 +975,7 @@ TEST(two_1a)
   db::box_convert<db::Box> bc1;
   db::box_convert<db::SimplePolygon> bc2;
   bs.set_scanner_threshold (0);
+  bs.set_scanner_threshold1 (0);
   bs.process (tr, 1, bc1, bc2);
   EXPECT_EQ (tr.str, "[i](2-11)(2-12)(1-11)(1-12)<1><2><11><12>(0-10)<0><10>[f]");
 }
@@ -1010,6 +1012,7 @@ TEST(two_1b)
   db::box_convert<db::Box> bc1;
   db::box_convert<db::SimplePolygon> bc2;
   bs.set_scanner_threshold (0);
+  bs.set_scanner_threshold1 (0);
   EXPECT_EQ (bs.process (tr, 1, bc1, bc2), true);
   EXPECT_EQ (tr.str, "[i](1-12)(2-12)(1-11)(2-11)<1><2><11><12>(0-10)<0><10>[f]");
 
@@ -1046,14 +1049,15 @@ TEST(two_1c)
   db::box_convert<db::Box> bc1;
   db::box_convert<db::SimplePolygon> bc2;
   bs.set_scanner_threshold (0);
+  bs.set_scanner_threshold1 (0);
   EXPECT_EQ (bs.process (tr, 1, bc1, bc2), true);
   EXPECT_EQ (tr.str, "[i]<0><10>(1-12)(2-12)(1-11)(2-11)<1><2><12><11>[f]");
 }
 
-void run_test2_two (tl::TestBase *_this, size_t n, double ff, db::Coord spread, bool touch = true)
+void run_test2_two (tl::TestBase *_this, size_t n1, size_t n2, double ff, db::Coord spread, bool touch = true, bool no_shortcut = true)
 {
   std::vector<db::Box> bb;
-  for (size_t i = 0; i < n; ++i) {
+  for (size_t i = 0; i < n1; ++i) {
     db::Coord x = rand () % spread;
     db::Coord y = rand () % spread;
     bb.push_back (db::Box (x, y, x + 100, y + 100));
@@ -1061,7 +1065,7 @@ void run_test2_two (tl::TestBase *_this, size_t n, double ff, db::Coord spread,
   }
 
   std::vector<db::SimplePolygon> bb2;
-  for (size_t i = 0; i < n; ++i) {
+  for (size_t i = 0; i < n2; ++i) {
     db::Coord x = rand () % spread;
     db::Coord y = rand () % spread;
     bb2.push_back (db::SimplePolygon (db::Box (x, y, x + 100, y + 100)));
@@ -1082,7 +1086,10 @@ void run_test2_two (tl::TestBase *_this, size_t n, double ff, db::Coord spread,
   db::box_convert<db::SimplePolygon> bc2;
   {
     tl::SelfTimer timer ("box-scanner");
-    bs.set_scanner_threshold (0);
+    if (no_shortcut) {
+      bs.set_scanner_threshold (0);
+      bs.set_scanner_threshold1 (0);
+    }
     bs.process (tr, touch ? 1 : 0, bc1, bc2);
   }
 
@@ -1118,45 +1125,60 @@ void run_test2_two (tl::TestBase *_this, size_t n, double ff, db::Coord spread,
 
 TEST(two_2a)
 {
-  run_test2_two(_this, 10, 0.0, 1000);
+  run_test2_two(_this, 10, 10, 0.0, 1000);
+  run_test2_two(_this, 10, 10, 0.0, 1000, true, false /*sub-threshold*/);
 }
 
 TEST(two_2b)
 {
-  run_test2_two(_this, 10, 0.0, 100);
+  run_test2_two(_this, 10, 10, 0.0, 100);
+  run_test2_two(_this, 10, 10, 0.0, 100, true, false /*sub-threshold*/);
 }
 
 TEST(two_2c)
 {
-  run_test2_two(_this, 10, 0.0, 10);
+  run_test2_two(_this, 10, 10, 0.0, 10);
+  run_test2_two(_this, 10, 10, 0.0, 10, true, false /*sub-threshold*/);
 }
 
 TEST(two_2d)
 {
-  run_test2_two(_this, 1000, 0.0, 1000);
+  run_test2_two(_this, 1000, 1000, 0.0, 1000);
 }
 
 TEST(two_2e)
 {
-  run_test2_two(_this, 1000, 2, 1000);
+  run_test2_two(_this, 1000, 1000, 2, 1000);
 }
 
 TEST(two_2f)
 {
-  run_test2_two(_this, 1000, 2, 1000, false);
+  run_test2_two(_this, 1000, 1000, 2, 1000, false);
 }
 
 TEST(two_2g)
 {
-  run_test2_two(_this, 1000, 2, 500);
+  run_test2_two(_this, 1000, 1000, 2, 500);
 }
 
 TEST(two_2h)
 {
-  run_test2_two(_this, 1000, 2, 100);
+  run_test2_two(_this, 1000, 1000, 2, 100);
 }
 
 TEST(two_2i)
 {
-  run_test2_two(_this, 10000, 2, 10000);
+  run_test2_two(_this, 10000, 1000, 2, 10000);
+}
+
+TEST(two_2j)
+{
+  run_test2_two(_this, 3, 1000, 0.0, 1000);
+  run_test2_two(_this, 3, 1000, 0.0, 1000, true, false /*sub-threshold*/);
+}
+
+TEST(two_2k)
+{
+  run_test2_two(_this, 1000, 3, 0.0, 1000);
+  run_test2_two(_this, 1000, 3, 0.0, 1000, true, false /*sub-threshold*/);
 }
diff --git a/src/db/unit_tests/dbHierProcessorTests.cc b/src/db/unit_tests/dbHierProcessorTests.cc
index 7e9fe165f..504f36c2e 100644
--- a/src/db/unit_tests/dbHierProcessorTests.cc
+++ b/src/db/unit_tests/dbHierProcessorTests.cc
@@ -1278,3 +1278,9 @@ TEST(FlatOperation)
   run_test_bool22_flat (_this, "hlp17_flat.oas", TMAndNot, 100, 101);
 }
 
+TEST(Arrays)
+{
+  //  Large arrays, NOT
+  run_test_bool2 (_this, "hlp18.oas", TMNot, 100);
+}
+
diff --git a/src/db/unit_tests/dbLayoutDiffTests.cc b/src/db/unit_tests/dbLayoutDiffTests.cc
index 011d2be8d..739b9a77d 100644
--- a/src/db/unit_tests/dbLayoutDiffTests.cc
+++ b/src/db/unit_tests/dbLayoutDiffTests.cc
@@ -105,6 +105,8 @@ TestDifferenceReceiver::print_cell_inst (const db::CellInstArrayWithProperties &
   }
   if (ci.properties_id () != 0) {
     m_os << " [" << ci.properties_id () << "]" << std::endl;
+  } else {
+    m_os << "" << std::endl;
   }
 }
 
@@ -489,7 +491,9 @@ TEST(1)
     "  c4 m45 *1 -10,20\n"
     "  c4 m45 *1 -10,20\n"
     "Not in b but in a:\n"
-    "  c5x r0 *1 10,-20  c5x m45 *1 -10,20Not in a but in b:\n"
+    "  c5x r0 *1 10,-20\n"
+    "  c5x m45 *1 -10,20\n"
+    "Not in a but in b:\n"
   );
 
   g = h;
@@ -951,7 +955,7 @@ TEST(3)
   c2h.shapes (0).insert (db::Polygon (db::Box (1, 2, 1003, 1006)));
 
   r.clear ();
-  eq = db::compare_layouts (g, h, db::layout_diff::f_verbose, 0, r); 
+  eq = db::compare_layouts (g, h, db::layout_diff::f_verbose, 0, r);
 
   EXPECT_EQ (eq, false);
   EXPECT_EQ (r.text (), 
@@ -965,7 +969,7 @@ TEST(3)
   );
 
   r.clear ();
-  eq = db::compare_layouts (g, h, db::layout_diff::f_verbose, 1, r); 
+  eq = db::compare_layouts (g, h, db::layout_diff::f_verbose, 1, r);
 
   EXPECT_EQ (eq, false);
   EXPECT_EQ (r.text (), 
@@ -1499,4 +1503,205 @@ TEST(7)
   EXPECT_EQ (r.text (), "");
 }
 
+TEST(8)
+{
+  db::Layout g;
+  g.insert_layer (0);
+  g.set_properties (0, db::LayerProperties (17, 0));
+  g.insert_layer (1);
+  g.set_properties (1, db::LayerProperties (42, 1));
+
+  db::cell_index_type c1i = g.add_cell ("c1");
+  db::cell_index_type c2i = g.add_cell ("c2x");
+  db::cell_index_type c3i = g.add_cell ("c3");
+  db::cell_index_type c4i = g.add_cell ("c4");
+  db::cell_index_type c5i = g.add_cell ("c5x");
+
+  {
+
+    db::Cell &c1 (g.cell (c1i));
+    db::Cell &c2 (g.cell (c2i));
+    db::Cell &c3 (g.cell (c3i));
+    db::Cell &c4 (g.cell (c4i));
+    db::Cell &c5 (g.cell (c5i));
+    c2.shapes (0).insert (db::Box (0, 1, 2, 3));
+
+    db::FTrans f (1, true);
+    db::Vector p (-10, 20);
+    db::Trans t (f.rot (), p);
+    db::Vector pp (10, -20);
+    db::Trans tt (0, pp);
+
+    //  c4->c1 (aref)
+    c4.insert (db::array <db::CellInst, db::Trans> (db::CellInst (c1.cell_index ()), t, db::Vector(1, 1), db::Vector (0, 2), 2, 3));
+    //  c5->c1
+    c5.insert (db::array <db::CellInst, db::Trans> (db::CellInst (c1.cell_index ()), t));
+    //  c3->c5 (3x)
+    c3.insert (db::array <db::CellInst, db::Trans> (db::CellInst (c5.cell_index ()), t));
+    c3.insert (db::array <db::CellInst, db::Trans> (db::CellInst (c5.cell_index ()), tt));
+    c3.insert (db::array <db::CellInst, db::Trans> (db::CellInst (c5.cell_index ()), t));
+    //  c4->c3
+    c4.insert (db::array <db::CellInst, db::Trans> (db::CellInst (c3.cell_index ()), t));
+    //  c4->c1
+    c4.insert (db::array <db::CellInst, db::Trans> (db::CellInst (c1.cell_index ()), tt));
+    //  c2->c1 (2x)
+    c2.insert (db::array <db::CellInst, db::Trans> (db::CellInst (c1.cell_index ()), t));
+    c2.insert (db::array <db::CellInst, db::Trans> (db::CellInst (c1.cell_index ()), tt));
+    //  c2->c4 (2x)
+    c2.insert (db::array <db::CellInst, db::Trans> (db::CellInst (c4.cell_index ()), t));
+    c2.insert (db::array <db::CellInst, db::Trans> (db::CellInst (c4.cell_index ()), t));
+
+  }
+
+  db::Layout h = g;
+
+  TestDifferenceReceiver r;
+  bool eq;
+
+  g.cell (c2i).shapes (0).insert (db::Box (1, 2, 1001, 1002));
+  g.cell (c2i).shapes (0).insert (db::Box (2, 3, 1002, 1003));
+  g.cell (c2i).shapes (0).insert (db::Box (2, 3, 1002, 1003));
+  g.cell (c2i).shapes (0).insert (db::Box (3, 4, 1003, 1004));
+  g.cell (c2i).shapes (0).insert (db::Box (3, 4, 1003, 1004));
+
+  h.cell (c2i).shapes (0).insert (db::Box (1, 2, 1001, 1002));
+  h.cell (c2i).shapes (0).insert (db::Box (1, 2, 1001, 1002));
+  h.cell (c2i).shapes (0).insert (db::Box (2, 3, 1002, 1003));
+  h.cell (c2i).shapes (0).insert (db::Box (4, 5, 1004, 1005));
+  h.cell (c2i).shapes (0).insert (db::Box (4, 5, 1004, 1005));
+
+  r.clear ();
+  eq = db::compare_layouts (g, h, db::layout_diff::f_verbose, 0, r);
+
+  EXPECT_EQ (eq, false);
+  EXPECT_EQ (r.text (),
+    "layout_diff: boxes differ for layer 17/0 in cell c2x\n"
+    "Not in b but in a:\n"
+    "  (2,3;1002,1003)\n"
+    "  (3,4;1003,1004)\n"
+    "  (3,4;1003,1004)\n"
+    "Not in a but in b:\n"
+    "  (1,2;1001,1002)\n"
+    "  (4,5;1004,1005)\n"
+    "  (4,5;1004,1005)\n"
+  );
+
+  r.clear ();
+  eq = db::compare_layouts (g, h, db::layout_diff::f_verbose + db::layout_diff::f_ignore_duplicates, 0, r);
+
+  EXPECT_EQ (eq, false);
+  EXPECT_EQ (r.text (),
+    "layout_diff: boxes differ for layer 17/0 in cell c2x\n"
+    "Not in b but in a:\n"
+    "  (3,4;1003,1004)\n"
+    "Not in a but in b:\n"
+    "  (4,5;1004,1005)\n"
+  );
+
+  //  duplicate instances
+  {
+    db::FTrans f (1, true);
+    db::Vector p (-10, 20);
+    db::Trans t (f.rot (), p);
+
+    h.cell(c4i).insert (db::array <db::CellInst, db::Trans> (db::CellInst (c1i), t, db::Vector(1, 1), db::Vector (0, 2), 2, 3));
+    h.cell(c4i).insert (db::array <db::CellInst, db::Trans> (db::CellInst (c1i), t));
+    h.cell(c4i).insert (db::array <db::CellInst, db::Trans> (db::CellInst (c1i), t));
+
+    g.cell(c5i).insert (db::array <db::CellInst, db::Trans> (db::CellInst (c1i), t));
+    g.cell(c5i).insert (db::array <db::CellInst, db::Trans> (db::CellInst (c1i), t, db::Vector(1, 1), db::Vector (0, 2), 2, 3));
+    g.cell(c5i).insert (db::array <db::CellInst, db::Trans> (db::CellInst (c1i), t, db::Vector(1, 1), db::Vector (0, 2), 2, 3));
+
+    db::cell_index_type c6i = g.add_cell ("c6");
+    g.cell(c5i).insert (db::array <db::CellInst, db::Trans> (db::CellInst (c6i), t));
+    g.cell(c5i).insert (db::array <db::CellInst, db::Trans> (db::CellInst (c6i), t));
+
+  }
+
+  r.clear ();
+  eq = db::compare_layouts (g, h, db::layout_diff::f_verbose, 0, r);
+
+  EXPECT_EQ (eq, false);
+  EXPECT_EQ (r.text (),
+    "layout_diff: cell c6 is not present in layout b, but in a\n"
+    "layout_diff: boxes differ for layer 17/0 in cell c2x\n"
+    "Not in b but in a:\n"
+    "  (2,3;1002,1003)\n"
+    "  (3,4;1003,1004)\n"
+    "  (3,4;1003,1004)\n"
+    "Not in a but in b:\n"
+    "  (1,2;1001,1002)\n"
+    "  (4,5;1004,1005)\n"
+    "  (4,5;1004,1005)\n"
+    "layout_diff: instances differ in cell c4\n"
+    "list for a:\n"
+    "  c1 r0 *1 10,-20\n"
+    "  c1 m45 *1 -10,20[a=1,1, b=0,2, na=2, nb=3]\n"
+    "  c3 m45 *1 -10,20\n"
+    "list for b:\n"
+    "  c1 r0 *1 10,-20\n"
+    "  c1 m45 *1 -10,20\n"
+    "  c1 m45 *1 -10,20\n"
+    "  c1 m45 *1 -10,20[a=1,1, b=0,2, na=2, nb=3]\n"
+    "  c1 m45 *1 -10,20[a=1,1, b=0,2, na=2, nb=3]\n"
+    "  c3 m45 *1 -10,20\n"
+    "Not in b but in a:\n"
+    "Not in a but in b:\n"
+    "  c1 m45 *1 -10,20\n"
+    "  c1 m45 *1 -10,20\n"
+    "  c1 m45 *1 -10,20[a=1,1, b=0,2, na=2, nb=3]\n"
+    "layout_diff: instances differ in cell c5x\n"
+    "list for a:\n"
+    "  c1 m45 *1 -10,20\n"
+    "  c1 m45 *1 -10,20\n"
+    "  c1 m45 *1 -10,20[a=1,1, b=0,2, na=2, nb=3]\n"
+    "  c1 m45 *1 -10,20[a=1,1, b=0,2, na=2, nb=3]\n"
+    "list for b:\n"
+    "  c1 m45 *1 -10,20\n"
+    "Not in b but in a:\n"
+    "  c1 m45 *1 -10,20\n"
+    "  c1 m45 *1 -10,20[a=1,1, b=0,2, na=2, nb=3]\n"
+    "  c1 m45 *1 -10,20[a=1,1, b=0,2, na=2, nb=3]\n"
+    "  c6 m45 *1 -10,20\n"
+    "  c6 m45 *1 -10,20\n"
+    "Not in a but in b:\n"
+  );
+
+  r.clear ();
+  eq = db::compare_layouts (g, h, db::layout_diff::f_verbose + db::layout_diff::f_ignore_duplicates, 0, r);
+
+  EXPECT_EQ (eq, false);
+  EXPECT_EQ (r.text (),
+    "layout_diff: cell c6 is not present in layout b, but in a\n"
+    "layout_diff: boxes differ for layer 17/0 in cell c2x\n"
+    "Not in b but in a:\n"
+    "  (3,4;1003,1004)\n"
+    "Not in a but in b:\n"
+    "  (4,5;1004,1005)\n"
+    "layout_diff: instances differ in cell c4\n"
+    "list for a:\n"
+    "  c1 r0 *1 10,-20\n"
+    "  c1 m45 *1 -10,20[a=1,1, b=0,2, na=2, nb=3]\n"
+    "  c3 m45 *1 -10,20\n"
+    "list for b:\n"
+    "  c1 r0 *1 10,-20\n"
+    "  c1 m45 *1 -10,20\n"
+    "  c1 m45 *1 -10,20[a=1,1, b=0,2, na=2, nb=3]\n"
+    "  c3 m45 *1 -10,20\n"
+    "Not in b but in a:\n"
+    "Not in a but in b:\n"
+    "  c1 m45 *1 -10,20\n"
+    "layout_diff: instances differ in cell c5x\n"
+    "list for a:\n"
+    "  c1 m45 *1 -10,20\n"
+    "  c1 m45 *1 -10,20[a=1,1, b=0,2, na=2, nb=3]\n"
+    "list for b:\n"
+    "  c1 m45 *1 -10,20\n"
+    "Not in b but in a:\n"
+    "  c1 m45 *1 -10,20[a=1,1, b=0,2, na=2, nb=3]\n"
+    "  c6 m45 *1 -10,20\n"
+    "Not in a but in b:\n"
+  );
+}
+
 
diff --git a/src/db/unit_tests/dbShapesTests.cc b/src/db/unit_tests/dbShapesTests.cc
index b2fce8945..b18e02bf3 100644
--- a/src/db/unit_tests/dbShapesTests.cc
+++ b/src/db/unit_tests/dbShapesTests.cc
@@ -1925,6 +1925,51 @@ TEST(7)
   }
 }
 
+//  copy, move, clear with shape types
+TEST(8)
+{
+  db::Manager m (true);
+
+  db::Layout layout (true, &m);
+  unsigned int lindex1 = layout.insert_layer ();
+  unsigned int lindex2 = layout.insert_layer ();
+
+  db::Cell &topcell = layout.cell (layout.add_cell ("TOP"));
+
+  topcell.shapes (lindex1).insert (db::Box (1, 2, 3, 4));
+  topcell.shapes (lindex1).insert (db::Polygon (db::Box (1, 2, 3, 4)));
+
+  {
+    db::Transaction trans (&m, "T1");
+    topcell.shapes (lindex2).insert (topcell.shapes (lindex1));
+    EXPECT_EQ (shapes_to_string (_this, topcell.shapes (lindex2)), "polygon (1,2;1,4;3,4;3,2) #0\nbox (1,2;3,4) #0\n");
+  }
+
+  m.undo ();
+  EXPECT_EQ (shapes_to_string (_this, topcell.shapes (lindex2)), "");
+
+  {
+    db::Transaction trans (&m, "T1");
+    topcell.shapes (lindex2).insert (topcell.shapes (lindex1), db::ShapeIterator::Boxes);
+    EXPECT_EQ (shapes_to_string (_this, topcell.shapes (lindex2)), "box (1,2;3,4) #0\n");
+  }
+
+  m.undo ();
+  EXPECT_EQ (shapes_to_string (_this, topcell.shapes (lindex2)), "");
+
+  topcell.shapes (lindex2).insert (topcell.shapes (lindex1));
+  EXPECT_EQ (shapes_to_string (_this, topcell.shapes (lindex2)), "polygon (1,2;1,4;3,4;3,2) #0\nbox (1,2;3,4) #0\n");
+
+  {
+    db::Transaction trans (&m, "T1");
+    topcell.shapes (lindex2).clear (db::ShapeIterator::Polygons);
+    EXPECT_EQ (shapes_to_string (_this, topcell.shapes (lindex2)), "box (1,2;3,4) #0\n");
+  }
+
+  m.undo ();
+  EXPECT_EQ (shapes_to_string (_this, topcell.shapes (lindex2)), shapes_to_string (_this, topcell.shapes (lindex1)));
+}
+
 TEST(10A)
 {
   if (db::default_editable_mode ()) { 
diff --git a/src/doc/doc/about/drc_ref_global.xml b/src/doc/doc/about/drc_ref_global.xml
index 91fa1a06e..3deac6889 100644
--- a/src/doc/doc/about/drc_ref_global.xml
+++ b/src/doc/doc/about/drc_ref_global.xml
@@ -1182,6 +1182,36 @@ See <a href="/about/drc_ref_netter.xml#netlist">Netter#netlist</a> for a descrip
 <p>
 See <a href="/about/drc_ref_netter.xml">Netter</a> for more details
 </p>
+<a name="new_report"/><h2>"new_report" - Creates a new report database object for use in "output"</h2>
+<keyword name="new_report"/>
+<p>Usage:</p>
+<ul>
+<li><tt>new_report(description [, filename [, cellname ] ])</tt></li>
+</ul>
+<p>
+This method creates an independent report object. This object
+can be used in "output" to send a layer to a different report than
+the default report or target.
+</p><p>
+Arguments are the same than for <a href="/about/drc_ref_global.xml#report">report</a>.
+</p><p>
+See <a href="/about/drc_ref_layer.xml#output">Layer#output</a> for details about this feature.
+</p>
+<a name="new_target"/><h2>"new_target" - Creates a new layout target object for use in "output"</h2>
+<keyword name="new_target"/>
+<p>Usage:</p>
+<ul>
+<li><tt>new_target(what [, cellname])</tt></li>
+</ul>
+<p>
+This method creates an independent target object. This object
+can be used in "output" to send a layer to a different layout file than
+the default report or target.
+</p><p>
+Arguments are the same than for <a href="/about/drc_ref_global.xml#target">target</a>.
+</p><p>
+See <a href="/about/drc_ref_layer.xml#output">Layer#output</a> for details about this feature.
+</p>
 <a name="no_borders"/><h2>"no_borders" - Reset the tile borders</h2>
 <keyword name="no_borders"/>
 <p>Usage:</p>
@@ -1413,6 +1443,21 @@ See <a href="/about/drc_ref_source.xml#polygons">Source#polygons</a> for a descr
 The primary input of the universal DRC function is the layer the <a href="/about/drc_ref_layer.xml#drc">Layer#drc</a> function
 is called on.
 </p>
+<a name="profile"/><h2>"profile" - Profiles the script and provides a runtime + memory statistics</h2>
+<keyword name="profile"/>
+<p>Usage:</p>
+<ul>
+<li><tt>profile</tt></li>
+<li><tt>profile(n)</tt></li>
+</ul>
+<p>
+Turns profiling on or off (default). In profiling mode, the 
+system will collect statistics about rules executed, their execution time
+and memory information. The argument specifies how many operations to 
+print at the end of the run. Without an argument, all operations are
+printed. Passing "false" for the argument will disable profiling. This is the
+default.
+</p>
 <a name="props_copy"/><h2>"props_copy" - Specifies "copy properties" on operations supporting user properties constraints</h2>
 <keyword name="props_copy"/>
 <p>
diff --git a/src/doc/doc/about/drc_ref_layer.xml b/src/doc/doc/about/drc_ref_layer.xml
index 4dbd218fa..6efff2012 100644
--- a/src/doc/doc/about/drc_ref_layer.xml
+++ b/src/doc/doc/about/drc_ref_layer.xml
@@ -2217,6 +2217,26 @@ a single <class_doc href="LayerInfo">LayerInfo</class_doc> object.
 </p><p>
 See <a href="/about/drc_ref_global.xml#report">report</a> and <a href="/about/drc_ref_global.xml#target">target</a> on how to configure output to a target layout
 or report database. 
+</p><p>
+See also <a href="/about/drc_ref_global.xml#new_target">new_target</a> and <a href="/about/drc_ref_global.xml#new_report">new_report</a> on how to create additional 
+targets for output. This allows saving certain layers to different files than
+the standard target or report. To do so, create a new target or report using one
+of these functions and pass that object to the corresponding "output" call as
+an additional argument.
+</p><p>
+Example:
+</p><p>
+<pre>
+check1 = ...
+check2 = ...
+check3 = ...
+
+second_report = new_report("Only for check2", "check2.lyrdb")
+
+check1.output("Check 1")
+check2.output("Check 2", second_report)
+check3.output("Check 3")
+</pre>
 </p>
 <a name="outside"/><h2>"outside" - Selects edges or polygons of self which are outside edges or polygons from the other layer</h2>
 <keyword name="outside"/>
diff --git a/src/doc/doc/manual/drc_runsets.xml b/src/doc/doc/manual/drc_runsets.xml
index 971bf9b79..7642c4c16 100644
--- a/src/doc/doc/manual/drc_runsets.xml
+++ b/src/doc/doc/manual/drc_runsets.xml
@@ -185,7 +185,7 @@ l.output("OUT")
 l.output(17, 0, "OUT")</pre>
 
   <p>
-  Output can be sent to other layouts using the "target" function:
+  Output can be sent to other layouts using the <a href="/about/drc_ref_global.xml#target">target</a> function:
   </p>
 
   <pre>
@@ -196,7 +196,7 @@ target("@2")
 target("out.gds", "OUT_TOP")</pre>
 
   <p>
-  Output can also be sent to a report database:
+  Output can also be sent to a report database using the <a href="/about/drc_ref_global.xml#report">report</a> function:
   </p>
 
   <pre>
@@ -234,6 +234,38 @@ l.output("check1", "The first check")</pre>
   unpredictable.
   </p>
 
+  <p>
+  It is possible to open "side" reports and targets and send layers to these
+  outputs without closing the default output. 
+  </p>
+
+  <p>
+  To open a "side report", use <a href="/about/drc_ref_global.xml#new_report">new_report</a>
+  in the same way you use "report". Instead of switching the output, this function will return a 
+  new report object that can be included in the argument list of "output" 
+  for the layer that is to be sent to that side report:
+  </p>
+
+  <pre>
+# opens a new side report
+side_report = new_report("Another report")
+...
+# Send data from layer l to new category "check1" to the side report
+l.output(side_report, "check1", "The first check")</pre>
+
+  <p>
+  In the same way, "side targets" can be opened using <a href="/about/drc_ref_global.xml#new_target">new_target</a>.
+  Such side targets open a way to write certain layers to other layout files.
+  This is very handy for debugging:
+  </p>
+
+  <pre>
+# opens a new side target for debugging
+debug_out = new_target("debug.gds")
+...
+# Send data from layer l to the debug output, layer 100/0
+l.output(debug_out, 100, 0)</pre>
+
 
   <h2>Dimension specifications</h2>
 
@@ -710,12 +742,12 @@ overlaps = layer.size(0.2).raw.merged(2)</pre>
   </p>
 
   <pre>
-  layer = input(1, 0)
-  layer.raw.sized(0.1).output(100, 0)
+layer = input(1, 0)
+layer.raw.sized(0.1).output(100, 0)
 
-  # this check will now be done on a raw layer, since the 
-  # previous raw call was putting the layer into raw mode
-  layer.width(0.2).ouput(101, 0)</pre>
+# this check will now be done on a raw layer, since the 
+# previous raw call was putting the layer into raw mode
+layer.width(0.2).ouput(101, 0)</pre>
 
   <p>
   The following two images show the effect of raw and clean mode:
@@ -792,20 +824,18 @@ overlaps = layer.size(0.2).raw.merged(2)</pre>
   </p>
 
   <pre>
-  ...
-  drc_w = input(1, 0).width(0.2)
-  ...
-  </pre>
+...
+drc_w = input(1, 0).width(0.2)
+...</pre>
 
   <p>
   can be written as:
   </p>
 
   <pre>
-  ...
-  drc_w = input(1, 0).drc(width &lt; 0.2)
-  ...
-  </pre>
+...
+drc_w = input(1, 0).drc(width &lt; 0.2)
+...</pre>
 
   <p>
   The <a href="/about/drc_ref_layer.xml#drc">drc</a> method is the "universal DRC" method.
@@ -845,12 +875,11 @@ overlaps = layer.size(0.2).raw.merged(2)</pre>
   </p>
 
   <pre>
-  ...
-  l1 = input(1, 0)
-  l2 = input(2, 0)
-  drc_sep = l1.drc(separation(l2) &lt;= 0.5)
-  ...
-  </pre>
+...
+l1 = input(1, 0)
+l2 = input(2, 0)
+drc_sep = l1.drc(separation(l2) &lt;= 0.5)
+...</pre>
 
   <p>
   Options are also specified together with the measurement and follow the same notation
@@ -858,10 +887,9 @@ overlaps = layer.size(0.2).raw.merged(2)</pre>
   </p>
 
   <pre>
-  ...
-  drc_w = input(1, 0).drc(width(projection) &lt; 0.2)
-  ...
-  </pre>
+...
+drc_w = input(1, 0).drc(width(projection) &lt; 0.2)
+...</pre>
 
   <p>
   However, the universal DRC is much more than a convenient way to write checks: 
@@ -879,10 +907,9 @@ overlaps = layer.size(0.2).raw.merged(2)</pre>
   </p>
 
   <pre>
-  ...
-  drc_ws = input(1, 0).drc((width &lt; 0.2) &amp; (space &lt; 0.3))
-  ...
-  </pre>
+...
+drc_ws = input(1, 0).drc((width &lt; 0.2) &amp; (space &lt; 0.3))
+...</pre>
 
   <p>
   The boolean AND is computed between the edges on the primary shape and returns the
@@ -891,12 +918,11 @@ overlaps = layer.size(0.2).raw.merged(2)</pre>
   </p>
 
   <pre>
-  ...
-  drc_ws1 = input(1, 0).width(0.2).edges
-  drc_ws2 = input(1, 0).space(0.3).edges
-  drc_ws = drc_ws1 &amp; drc_ws2
-  ...
-  </pre>
+...
+drc_ws1 = input(1, 0).width(0.2).edges
+drc_ws2 = input(1, 0).space(0.3).edges
+drc_ws = drc_ws1 &amp; drc_ws2
+...</pre>
 
   <p>
   The reason is that performing the boolean computation in the local loop can be 
@@ -933,11 +959,10 @@ overlaps = layer.size(0.2).raw.merged(2)</pre>
   </p>
 
   <pre>
-  ...
-  drc_w = input(1, 0).width(0.2)
-  log("Number of width violations: #{drc_w.data.size}")
-  ...
-  </pre>
+...
+drc_w = input(1, 0).width(0.2)
+log("Number of width violations: #{drc_w.data.size}")
+...</pre>
 
   <p>
   The <a href="/about/drc_ref_global.xml#error">error</a> function can be used to output error messages
@@ -946,11 +971,23 @@ overlaps = layer.size(0.2).raw.merged(2)</pre>
   </p>
 
   <pre>
-  log_file("drc_log.txt")
-  verbose(true)
-  info("This message will be sent to the log file")
-  ...
-  </pre>
+log_file("drc_log.txt")
+verbose(true)
+info("This message will be sent to the log file")
+...</pre>
+
+  <p>
+  The <a href="/about/drc_ref_global.xml#profile">profile</a> function will collect profiling 
+  information during the DRC run. At the end of the script, the operations are printed to the log
+  output, sorted by their CPU time and approximate memory footprint. "profile" can be given a 
+  numerical argument indicating the number of operations to print. Lower-ranking operations are
+  skipped in that case. By default, all operations are printed.
+  </p>
+
+  <pre>
+# enables profiling
+profile
+...</pre>
   
 
   <h2>The tiling option</h2>
@@ -1003,8 +1040,7 @@ threads(4)
 # Disable tiling
 flat
 
-... non-tiled operations ...
-</pre>
+... non-tiled operations ...</pre>
 
   <p>
   Some operations implicitly specify a tile border. If the tile border is known (see length example above), explicit borders
diff --git a/src/drc/drc/built-in-macros/_drc_engine.rb b/src/drc/drc/built-in-macros/_drc_engine.rb
index 17edb9e2e..6bc5f4c72 100644
--- a/src/drc/drc/built-in-macros/_drc_engine.rb
+++ b/src/drc/drc/built-in-macros/_drc_engine.rb
@@ -13,6 +13,125 @@ module DRC
     end
   end
 
+  class OutputChannel
+    def initialize(engine)
+      @engine = engine
+    end
+    def is_rdb?
+      false
+    end
+    def cellname=(cellname)
+      # reimplement
+    end
+    def cell
+      # reimplement
+    end
+    def write
+      # reimplement
+    end
+    def finish(final)
+      # reimplement
+    end
+    def write
+      # reimplement
+    end
+    def layout
+      nil
+    end
+    def rdb
+      nil
+    end
+  end
+
+  class LayoutOutputChannel < OutputChannel
+
+    def initialize(engine, layout, cell, file_name)
+      super(engine)
+      @layout = layout
+      @cell = cell
+      @file_name = file_name
+    end
+
+    def cellname=(cellname)
+      @cell = @layout.cell(cellname) || @layout.create_cell(cellname)
+    end
+
+    def is_rdb?
+      false
+    end
+
+    def finish(final, view)
+      write
+    end
+
+    def write
+      if @file_name
+        opt = RBA::SaveLayoutOptions::new
+        gzip = opt.set_format_from_filename(@file_name)
+        @engine.info("Writing layout file: #{@file_name} ..")
+        @layout.write(@file_name, gzip, opt)
+      end
+    end
+
+    def layout
+      @layout
+    end
+
+    def cell
+      @cell
+    end
+
+  end
+
+  class RDBOutputChannel < OutputChannel
+
+    def initialize(engine, rdb, rdb_index, cellname, file_name)
+      super(engine)
+      @rdb = rdb
+      @rdb_index = rdb_index
+      @cell = cellname && rdb.create_cell(cellname)
+      @file_name = file_name
+    end
+
+    def cellname=(cellname)
+      @cell = nil
+      @rdb.each_cell do |c|
+        if c.name == cellname
+          @cell = c
+        end
+      end
+      @cell ||= @rdb.create_cell(cellname)
+    end
+
+    def is_rdb?
+      true
+    end
+
+    def finish(final, view)
+      write
+      if final && view
+        view.show_rdb(@rdb_index, view.active_cellview_index)
+      end
+    end
+
+    def write
+      if @file_name
+        rdb_file = @engine._make_path(@file_name)
+        @engine.info("Writing report database: #{rdb_file} ..")
+        @rdb.save(rdb_file)
+      end
+    end
+
+    def rdb
+      @rdb
+    end
+
+    def cell
+      @cell
+    end
+
+  end
+
   # The DRC engine
   
   # %DRC%
@@ -40,11 +159,9 @@ module DRC
       @def_source = nil
       @dbu_read = false
       use_dbu(@def_layout && @def_layout.dbu)
-      @output_layout = nil
-      @output_rdb = nil
-      @output_rdb_file = nil
-      @output_rdb_cell = nil
       @show_l2ndb = nil
+      @def_output = nil
+      @other_outputs = []
       @output_l2ndb_file = nil
       @target_netlist_file = nil
       @target_netlist_format = nil
@@ -70,6 +187,9 @@ module DRC
       dss._destroy
 
       @verbose = false
+      @profile = false
+      @profile_n = 0
+      @profile_info = {}
 
       @in_context = nil
 
@@ -711,6 +831,26 @@ module DRC
       end
     end
 
+    # %DRC%
+    # @name profile
+    # @brief Profiles the script and provides a runtime + memory statistics
+    # @synopsis profile
+    # @synopsis profile(n)
+    # Turns profiling on or off (default). In profiling mode, the 
+    # system will collect statistics about rules executed, their execution time
+    # and memory information. The argument specifies how many operations to 
+    # print at the end of the run. Without an argument, all operations are
+    # printed. Passing "false" for the argument will disable profiling. This is the
+    # default.
+
+    def profile(n = 0)
+      if !n.is_a?(1.class) && n != nil && n != false
+        raise("Argument to 'profile' must be either an integer number or nil")
+      end
+      @profile = !!n
+      @profile_n = [n || 0, 0].max
+    end
+
     # %DRC%
     # @name verbose?
     # @brief Returns true, if verbose mode is enabled
@@ -1340,46 +1480,42 @@ module DRC
 
       self._context("report") do
 
-        @output_rdb_file = filename
+        # finish what we got so far
+        _finish(false)
 
-        name = filename && File::basename(filename)
-        name ||= "DRC"
-        
-        @output_rdb_index = nil
-
-        view = RBA::LayoutView::current
-        if view
-          if self._rdb_index
-            @output_rdb = RBA::ReportDatabase::new("")   # reuse existing name
-            @output_rdb_index = view.replace_rdb(self._rdb_index, @output_rdb)
-          else
-            @output_rdb = RBA::ReportDatabase::new(name)
-            @output_rdb_index = view.add_rdb(@output_rdb)
-          end
-        else
-          @output_rdb = RBA::ReportDatabase::new(name)
-        end
-        
-        @output_layout = nil
-        @output_cell = nil
-        @output_layout_file = nil
-
-        cn = nil
-        cn ||= @def_cell && @def_cell.name
-        cn ||= source && source.cell_name
-        cn ||= cellname
-
-        cn || raise("No cell name specified - either the source was not specified before 'report' or there is no default source. In the latter case, specify a cell name as the third parameter")
-
-        @output_rdb_cell = @output_rdb.create_cell(cn)
-        @output_rdb.generator = self._generator
-        @output_rdb.top_cell_name = cn
-        @output_rdb.description = description
+        @def_output = nil
+        @def_output = _make_report(description, filename, cellname)
 
       end
       
     end
 
+    # %DRC%
+    # @name new_report
+    # @brief Creates a new report database object for use in "output"
+    # @synopsis new_report(description [, filename [, cellname ] ])
+    # 
+    # This method creates an independent report object. This object
+    # can be used in "output" to send a layer to a different report than
+    # the default report or target.
+    #
+    # Arguments are the same than for \global#report.
+    #
+    # See \Layer#output for details about this feature.
+
+    def new_report(description, filename = nil, cellname = nil)
+
+      output = nil
+
+      self._context("new_report") do
+        output = _make_report(description, filename, cellname)
+        @other_outputs << output
+      end
+
+      output
+      
+    end
+
     # %DRC%
     # @name report_netlist
     # @brief Specifies an extracted netlist report for output
@@ -1456,25 +1592,13 @@ module DRC
         # finish what we got so far
         _flush
         
-        if @output_rdb
-        
-          cell = nil
-          @output_rdb.each_cell do |c|
-            if c.name == cellname
-              cell = c
-            end
+        if ! @def_output
+          if @def_layout
+            # establish a new default output from the default layout on this occasion
+            @def_output = LayoutOutputChannel::new(self, @def_layout, cellname.to_s, nil)
           end
-          
-          cell ||= @output_rdb.create_cell(cellname)
-          @output_rdb_cell = cell
-          
         else
-        
-          @output_layout ||= @def_layout
-          if @output_layout
-            @output_cell = @output_layout.cell(cellname.to_s) || @output_layout.create_cell(cellname.to_s)
-          end
-          
+          @def_output.cellname = cellname.to_s
         end
 
       end
@@ -1512,51 +1636,40 @@ module DRC
     
         # finish what we got so far
         _finish(false)
-            
-        if arg.is_a?(String)
-        
-          if arg =~ /^@(\d+|\+)/
-            view = RBA::LayoutView::current
-            view || raise("No view open")
-            if $1 == "+"
-              n = view.create_layout(true)
-              cellname ||= (@def_cell ? @def_cell.name : "TOP")
-            else
-              n = $1.to_i - 1
-            end
-            (n >= 0 && view.cellviews > n) || raise("Invalid layout index @#{n + 1}")
-            cv = view.cellview(n)
-            cv.is_valid? || raise("Invalid layout @#{n + 1}")
-            @output_layout = cv.layout
-            @output_cell = cellname ? (@output_layout.cell(cellname.to_s) || @output_layout.create_cell(cellname.to_s)) : cv.cell
-            cv.cell = @output_cell
-            @output_layout_file = nil
-          else
-            @output_layout = RBA::Layout::new
-            @output_cell = cellname && @output_layout.create_cell(cellname.to_s)
-            @output_layout_file = arg
-          end
-          
-        elsif arg.is_a?(RBA::Layout)
-        
-          @output_layout = arg
-          @output_cell = cellname && (@output_layout.cell(cellname.to_s) || @output_layout.create_cell(cellname.to_s))
-          @output_layout_file = nil
-          
-        elsif arg.is_a?(RBA::Cell)
-        
-          @output_layout = arg.layout
-          @output_cell = arg
-          @output_layout_file = nil
 
-        else
-          raise("Invalid argument '" + arg.inspect + "'")
-        end
-    
+        @def_output = nil
+        @def_output = _make_target(arg, cellname)
+
       end
 
     end
-    
+            
+    # %DRC%
+    # @name new_target
+    # @brief Creates a new layout target object for use in "output"
+    # @synopsis new_target(what [, cellname])
+    # 
+    # This method creates an independent target object. This object
+    # can be used in "output" to send a layer to a different layout file than
+    # the default report or target.
+    #
+    # Arguments are the same than for \global#target.
+    #
+    # See \Layer#output for details about this feature.
+
+    def new_target(arg, cellname = nil)
+
+      output = nil
+
+      self._context("new_target") do
+        output = _make_target(arg, cellname)
+        @other_outputs << output
+      end
+
+      output
+      
+    end
+
     # %DRC%
     # @name box 
     # @brief Creates a box object
@@ -2267,13 +2380,16 @@ CODE
       end
       
       t = RBA::Timer::new
+
       t.start
       self._process_events
-      if @force_gc || Time::now - @time > 0.5
+      if @force_gc || Time::now - @time > 0.5 || @profile
         GC.start    # force a garbage collection before the operation to free unused memory
         @time = Time::now
       end
+      mem_before = RBA::Timer::memory_size
       res = yield
+      mem_after = RBA::Timer::memory_size
       t.stop
 
       begin
@@ -2283,15 +2399,25 @@ CODE
           # Report result statistics
           _result_info(res, 1)
 
-          mem = RBA::Timer::memory_size
-          if mem > 0
-            info("Elapsed: #{'%.3f'%(t.sys+t.user)}s  Memory: #{'%.2f'%(mem/(1024*1024))}M", 1)
+          if mem_after > 0
+            info("Elapsed: #{'%.3f'%(t.sys+t.user)}s  Memory: #{'%.2f'%(mem_after/(1024*1024))}M", 1)
           else
             info("Elapsed: #{'%.3f'%(t.sys+t.user)}s", 1)
           end
 
         end
 
+        if @profile
+
+          # calls, sys time (in sec), user time (in sec), memory added (in bytes)
+          info = (@profile_info[desc] ||= [ 0, 0.0, 0.0, 0 ])
+          info[0] += 1
+          info[1] += t.sys
+          info[2] += t.user
+          info[3] += mem_after - mem_before
+
+        end
+
       ensure
 
         # disable progress again
@@ -2477,8 +2603,8 @@ CODE
     end
 
     def _output_layout
-      if @output_layout 
-        output = @output_layout
+      if @def_output && @def_output.layout
+        output = @def_output.layout
       else
         output = @def_layout
         output || raise("No output layout specified")
@@ -2487,19 +2613,79 @@ CODE
     end
     
     def _output_cell
-      if @output_layout 
-        if @output_cell
-          output_cell = @output_cell
+      if @def_output && @def_output.layout 
+        if @def_output.cell
+          output_cell = @def_output.cell
         elsif @def_cell
-          output_cell = @output_layout.cell(@def_cell.name) || @output_layout.create_cell(@def_cell.name)
+          output_layout = @def_output.layout
+          output_cell = output_layout.cell(@def_cell.name) || output_layout.create_cell(@def_cell.name)
         end
         output_cell || raise("No output cell specified (see 'target' instruction)")
       else
-        output_cell = @output_cell || @def_cell
+        output_cell = @def_cell
         output_cell || raise("No output cell specified")
       end
       output_cell
     end
+
+    def _dump_profile
+
+      if @profile_info.empty?
+        return
+      end
+
+      desc_title = "Operation"
+      calls_title = "# calls"
+      time_title = "Time (s)"
+      memory_title = "Memory (k)"
+      titles = [ desc_title, calls_title, time_title, memory_title ]
+
+      max_len_desc  = [ @profile_info.keys.collect { |s| s.size }.max, desc_title.size ].max
+      max_len_calls = [ @profile_info.values.collect { |v| v[0].to_s.size }.max, calls_title.size ].max
+      max_len_time  = [ @profile_info.values.collect { |v| ("%.3f" % (v[1] + v[2])).to_s.size }.max, time_title.size ].max
+      max_len_mem   = [ @profile_info.values.collect { |v| v[3].to_s.size }.max, memory_title.size ].max
+
+      fmt = "%-" + max_len_desc.to_s + "s  " +
+            "%-" + max_len_calls.to_s + "d  " +
+            "%-" + max_len_time.to_s + ".3f  " + 
+            "%-" + max_len_mem.to_s + ".0f" 
+
+      fmt_title = "%-" + max_len_desc.to_s + "s  " +
+                  "%-" + max_len_calls.to_s + "s  " +
+                  "%-" + max_len_time.to_s + "s  " + 
+                  "%-" + max_len_mem.to_s + "s" 
+
+      pi = @profile_info.keys.collect { |s| [s] + @profile_info[s] }.collect do |desc,calls,sys_time,user_time,memory|
+        [ desc, calls, sys_time + user_time, memory.to_f / 1024.0 ]
+      end
+
+      self.log("")
+      self.log("Operations by execution time\n")
+      self.log(fmt_title % titles)
+      n = 1
+      pi.sort { |a,b| b[2] <=> a[2] }.each do |info|
+        self.log(fmt % info)
+        n += 1
+        if @profile_n > 0 && n > @profile_n
+          self.log("... (%d entries skipped)" % (pi.size - @profile_n))
+          break
+        end
+      end
+
+      self.log("")
+      self.log("Operations by memory adder\n")
+      self.log(fmt_title % titles)
+      n = 1
+      pi.sort { |a,b| b[3] <=> a[3] }.each do |info|
+        self.log(fmt % info)
+        n += 1
+        if @profile_n > 0 && n > @profile_n
+          self.log("... (%d entries skipped)" % (pi.size - @profile_n))
+          break
+        end
+      end
+
+    end
     
     def _start(job_description)
     
@@ -2528,39 +2714,32 @@ CODE
       begin
 
         _flush    
-        
+
         view = RBA::LayoutView::current
 
-        # save the report database if requested
-        if @output_rdb_file && final
-          rdb_file = _make_path(@output_rdb_file)
-          info("Writing report database: #{rdb_file} ..")
-          @output_rdb.save(rdb_file)
+        @def_output && @def_output.finish(final, view)
+
+        if final
+          @other_outputs.each do |output|
+            output.finish(final, view)
+          end
         end
-        if @output_rdb && final && view
-          view.show_rdb(@output_rdb_index, view.active_cellview_index)
-        end
-      
-        # save the output file if requested
-        if @output_layout && @output_layout_file
-          opt = RBA::SaveLayoutOptions::new
-          gzip = opt.set_format_from_filename(@output_layout_file)
-          info("Writing layout file: #{@output_layout_file} ..")
-          @output_layout.write(@output_layout_file, gzip, opt)
+
+        # dump the profile information
+        if @profile && final
+          _dump_profile
         end
         
         # create the new layers as visual layers if necessary
         if view
         
-          output = @output_layout || @def_layout
+          output = ( @def_output && @def_output.layout ) || @def_layout
           cv_index = nil
           view.cellviews.times do |cvi|
             view.cellview(cvi).layout == output && cv_index = cvi
           end
           if cv_index
           
-            view = RBA::LayoutView::current
-            
             # clear selection
             view.cancel 
       
@@ -2634,13 +2813,10 @@ CODE
       ensure
 
         @output_layers = []
-        @output_layout = nil
-        @output_layout_file = nil
-        @output_cell = nil
-        @output_rdb_file = nil
-        @output_rdb_cell = nil
-        @output_rdb = nil
-        @output_rdb_index = nil
+        @def_output = nil
+        if final
+          @other_outputs = []
+        end
         @show_l2ndb = nil
         @output_l2ndb_file = nil
 
@@ -2933,21 +3109,36 @@ CODE
     
     def _output(data, *args)
 
-      if @output_rdb
+      channel = args.find { |a| a.is_a?(OutputChannel) }
+      if ! channel
+        if ! @def_output
+          @def_output = LayoutOutputChannel::new(self, self._output_layout, self._output_cell, nil)
+        end
+        channel = @def_output
+      end
+
+      args = args.select { |a| !a.is_a?(OutputChannel) }
+
+      if channel.rdb
         
         if args.size < 1
           raise("Invalid number of arguments - category name and optional description expected")
         end
 
-        cat = @output_rdb.create_category(args[0].to_s)
+        output_rdb = channel.rdb
+        output_cell = channel.cell
+
+        cat = output_rdb.create_category(args[0].to_s)
         args[1] && cat.description = args[1]
 
-        cat.scan_collection(@output_rdb_cell, RBA::CplxTrans::new(self.dbu), data)
+        cat.scan_collection(output_cell, RBA::CplxTrans::new(self.dbu), data)
       
-      else 
+      end
 
-        output = self._output_layout
-        output_cell = self._output_cell
+      if channel.layout
+
+        output = channel.layout
+        output_cell = channel.cell
 
         info = nil
         if args.size == 1
@@ -2977,14 +3168,16 @@ CODE
 
         begin
 
-          if !@used_output_layers[li]
-            @output_layers.push(li)
-            # Note: to avoid issues with output onto the input layer, we
-            # output to a temp layer and later swap both. The simple implementation
-            # did a clear here and the effect of that was that the data potentially
-            # got invalidated.
-            tmp = output.insert_layer(RBA::LayerInfo::new)
-            @used_output_layers[li] = true
+          if channel == @def_output
+            if !@used_output_layers[li]
+              @output_layers.push(li)
+              # Note: to avoid issues with output onto the input layer, we
+              # output to a temp layer and later swap both. The simple implementation
+              # did a clear here and the effect of that was that the data potentially
+              # got invalidated.
+              tmp = output.insert_layer(RBA::LayerInfo::new)
+              @used_output_layers[li] = true
+            end
           end
 
           # insert the data into the output layer
@@ -3020,7 +3213,111 @@ CODE
       @layout_sources[name] = src
       src
     end
+    
+    def _make_report(description, filename, cellname)
 
+      output_rdb_file = filename
+
+      name = filename && File::basename(filename)
+      name ||= "DRC"
+      
+      output_rdb_index = nil
+
+      view = RBA::LayoutView::current
+      if view
+        if self._rdb_index
+          output_rdb = RBA::ReportDatabase::new("")   # reuse existing name
+          output_rdb_index = view.replace_rdb(self._rdb_index, output_rdb)
+        else
+          output_rdb = RBA::ReportDatabase::new(name)
+          output_rdb_index = view.add_rdb(output_rdb)
+        end
+      else
+        output_rdb = RBA::ReportDatabase::new(name)
+      end
+      
+      cn = cellname && cellname.to_s
+      cn ||= @def_cell && @def_cell.name
+      cn ||= source && source.cell_name
+
+      cn || raise("No cell name specified - either the source was not specified before 'report' or there is no default source. In the latter case, specify a cell name as the third parameter")
+
+      output_rdb.generator = self._generator
+      output_rdb.top_cell_name = cn
+      output_rdb.description = description
+
+      RDBOutputChannel::new(self, output_rdb, output_rdb_index, cn, output_rdb_file)
+      
+    end
+
+    def _make_target(arg, cellname = nil)
+
+      if arg.is_a?(String)
+      
+        if arg =~ /^@(\d+|\+)/
+
+          view = RBA::LayoutView::current
+          view || raise("No view open")
+          if $1 == "+"
+            n = view.create_layout(true)
+            cellname ||= (@def_cell ? @def_cell.name : "TOP")
+          else
+            n = $1.to_i - 1
+          end
+
+          (n >= 0 && view.cellviews > n) || raise("Invalid layout index @#{n + 1}")
+
+          cv = view.cellview(n)
+          cv.is_valid? || raise("Invalid layout @#{n + 1}")
+
+          output_layout = cv.layout
+          output_cell = cellname ? (output_layout.cell(cellname.to_s) || output_layout.create_cell(cellname.to_s)) : cv.cell
+          cv.cell = output_cell
+          output_layout_file = nil
+
+        else
+
+          cn = cellname && cellname.to_s
+          cn ||= @def_cell && @def_cell.name
+          cn ||= @def_source && @def_source.cell_obj && @def_source.cell_obj.name
+
+          cn || raise("No cell name specified - either the source was not specified before 'report' or there is no default source. In the latter case, specify a cell name as the third parameter")
+
+          output_layout = RBA::Layout::new
+          output_cell = output_layout.create_cell(cn)
+          output_layout_file = arg
+
+        end
+        
+      elsif arg.is_a?(RBA::Layout)
+      
+        output_layout = arg
+
+        output_cell = cellname && (output_layout.cell(cellname.to_s) || output_layout.create_cell(cellname.to_s))
+        if ! output_cell
+          begin
+            output_cell = output_layout.top_cell
+          rescue 
+            raise("No cell name specified and the layout does not have a unique top cell - specify the name of the top cell to write the output to")
+          end
+        end
+
+        output_layout_file = nil
+        
+      elsif arg.is_a?(RBA::Cell)
+      
+        output_layout = arg.layout
+        output_cell = arg
+        output_layout_file = nil
+
+      else
+        raise("Invalid argument '" + arg.inspect + "'")
+      end
+    
+      output = LayoutOutputChannel::new(self, output_layout, output_cell, output_layout_file)
+
+    end
+    
   end
  
 end
diff --git a/src/drc/drc/built-in-macros/_drc_layer.rb b/src/drc/drc/built-in-macros/_drc_layer.rb
index e434c9d1d..30ea3a692 100644
--- a/src/drc/drc/built-in-macros/_drc_layer.rb
+++ b/src/drc/drc/built-in-macros/_drc_layer.rb
@@ -5007,6 +5007,26 @@ CODE
     #
     # See \global#report and \global#target on how to configure output to a target layout
     # or report database. 
+    # 
+    # See also \global#new_target and \global#new_report on how to create additional 
+    # targets for output. This allows saving certain layers to different files than
+    # the standard target or report. To do so, create a new target or report using one
+    # of these functions and pass that object to the corresponding "output" call as
+    # an additional argument.
+    #
+    # Example:
+    #
+    # @code
+    # check1 = ...
+    # check2 = ...
+    # check3 = ...
+    #
+    # second_report = new_report("Only for check2", "check2.lyrdb")
+    #
+    # check1.output("Check 1")
+    # check2.output("Check 2", second_report)
+    # check3.output("Check 3")
+    # @/code
     
     def output(*args)
       @engine._context("output") do
diff --git a/src/drc/unit_tests/drcSimpleTests.cc b/src/drc/unit_tests/drcSimpleTests.cc
index 8b24c918d..c0825e751 100644
--- a/src/drc/unit_tests/drcSimpleTests.cc
+++ b/src/drc/unit_tests/drcSimpleTests.cc
@@ -731,6 +731,75 @@ TEST(14_SwitchingTargets)
   db::compare_layouts (_this, layout2, au2, db::NoNormalization);
 }
 
+TEST(14b_SideTargetsAndReports)
+{
+  std::string rs = tl::testdata ();
+  rs += "/drc/drcSimpleTests_14b.drc";
+
+  std::string input = tl::testdata ();
+  input += "/drc/drcSimpleTests_14b.gds";
+
+  std::string au = tl::testdata ();
+  au += "/drc/drcSimpleTests_au14b.gds";
+
+  std::string au2 = tl::testdata ();
+  au2 += "/drc/drcSimpleTests_au14b_2.gds";
+
+  std::string au_report = tl::testdata ();
+  au_report += "/drc/drcSimpleTests_au14b.lyrdb";
+
+  std::string au_report2 = tl::testdata ();
+  au_report2 += "/drc/drcSimpleTests_au14b_2.lyrdb";
+
+  std::string output = this->tmp_file ("tmp.gds");
+  std::string output2 = this->tmp_file ("tmp2.gds");
+  std::string report = this->tmp_file ("tmp.lydrc");
+  std::string report2 = this->tmp_file ("tmp2.lydrc");
+
+  {
+    //  Set some variables
+    lym::Macro config;
+    config.set_text (tl::sprintf (
+        "$drc_force_gc = true\n"
+        "$drc_test_source = '%s'\n"
+        "$drc_test_target = '%s'\n"
+        "$drc_test_target2 = '%s'\n"
+        "$drc_test_report = '%s'\n"
+        "$drc_test_report2 = '%s'\n"
+      , input, output, output2, report, report2)
+    );
+    config.set_interpreter (lym::Macro::Ruby);
+    EXPECT_EQ (config.run (), 0);
+  }
+
+  lym::Macro drc;
+  drc.load_from (rs);
+  EXPECT_EQ (drc.run (), 0);
+
+  db::Layout layout;
+
+  {
+    tl::InputStream stream (output);
+    db::Reader reader (stream);
+    reader.read (layout);
+  }
+
+  db::compare_layouts (_this, layout, au, db::NoNormalization);
+
+  db::Layout layout2;
+
+  {
+    tl::InputStream stream (output2);
+    db::Reader reader (stream);
+    reader.read (layout2);
+  }
+
+  db::compare_layouts (_this, layout2, au2, db::NoNormalization);
+
+  compare_text_files (report, au_report);
+  compare_text_files (report2, au_report2);
+}
+
 TEST(15_issue548)
 {
   std::string rs = tl::testdata ();
diff --git a/src/lay/lay/layGSIHelpProvider.cc b/src/lay/lay/layGSIHelpProvider.cc
index eda190c67..c79df181f 100644
--- a/src/lay/lay/layGSIHelpProvider.cc
+++ b/src/lay/lay/layGSIHelpProvider.cc
@@ -118,6 +118,10 @@ std::string escape_xml_with_formatting (const std::string &s, bool &in_code)
         r += "<u>";
       } else if (sc.test ("@/u")) {
         r += "</u>";
+      } else if (sc.test ("@tt")) {
+        r += "<tt>";
+      } else if (sc.test ("@/tt")) {
+        r += "</tt>";
       } else if (sc.test ("@i")) {
         r += "<i>";
       } else if (sc.test ("@/i")) {
diff --git a/src/plugins/streamers/gds2/db_plugin/dbGDS2Reader.cc b/src/plugins/streamers/gds2/db_plugin/dbGDS2Reader.cc
index 8167b02d5..64253e5e0 100644
--- a/src/plugins/streamers/gds2/db_plugin/dbGDS2Reader.cc
+++ b/src/plugins/streamers/gds2/db_plugin/dbGDS2Reader.cc
@@ -127,11 +127,19 @@ GDS2Reader::get_record ()
   return rec_id;
 }
 
+void
+GDS2Reader::record_underflow_error ()
+{
+  error (tl::to_string (tr ("Record too short")));
+}
+
 inline int 
 GDS2Reader::get_int ()
 {
   unsigned char *b = mp_rec_buf + m_recptr;
-  m_recptr += 4;
+  if ((m_recptr += 4) > m_reclen) {
+    record_underflow_error ();
+  }
 
   int32_t l = *((int32_t *)b);
   gds2h (l);
@@ -142,7 +150,9 @@ inline short
 GDS2Reader::get_short ()
 {
   unsigned char *b = mp_rec_buf + m_recptr;
-  m_recptr += 2;
+  if ((m_recptr += 2) > m_reclen) {
+    record_underflow_error ();
+  }
 
   int16_t s = *((int16_t *)b);
   gds2h (s);
@@ -153,7 +163,9 @@ inline unsigned short
 GDS2Reader::get_ushort ()
 {
   unsigned char *b = mp_rec_buf + m_recptr;
-  m_recptr += 2;
+  if ((m_recptr += 2) > m_reclen) {
+    record_underflow_error ();
+  }
 
   uint16_t s = *((uint16_t *)b);
   gds2h ((int16_t &) s);
@@ -164,7 +176,9 @@ inline double
 GDS2Reader::get_double ()
 {
   unsigned char *b = mp_rec_buf + m_recptr;
-  m_recptr += 8;
+  if ((m_recptr += 8) > m_reclen) {
+    record_underflow_error ();
+  }
 
   uint32_t l0 = ((uint32_t *)b) [0];
   gds2h ((int32_t &) l0);
diff --git a/src/plugins/streamers/gds2/db_plugin/dbGDS2Reader.h b/src/plugins/streamers/gds2/db_plugin/dbGDS2Reader.h
index 33cce1401..17eb2b504 100644
--- a/src/plugins/streamers/gds2/db_plugin/dbGDS2Reader.h
+++ b/src/plugins/streamers/gds2/db_plugin/dbGDS2Reader.h
@@ -106,6 +106,8 @@ private:
   virtual void get_time (unsigned int *mod_time, unsigned int *access_time);
   virtual GDS2XY *get_xy_data (unsigned int &length);
   virtual void progress_checkpoint ();
+
+  void record_underflow_error ();
 };
 
 }
diff --git a/src/plugins/streamers/gds2/db_plugin/dbGDS2ReaderBase.cc b/src/plugins/streamers/gds2/db_plugin/dbGDS2ReaderBase.cc
index 90e84d65d..ad6eed607 100644
--- a/src/plugins/streamers/gds2/db_plugin/dbGDS2ReaderBase.cc
+++ b/src/plugins/streamers/gds2/db_plugin/dbGDS2ReaderBase.cc
@@ -278,6 +278,10 @@ GDS2ReaderBase::do_read (db::Layout &layout)
 
     get_string (m_cellname);
 
+    if (m_cellname.empty ()) {
+      error (tl::to_string (tr ("Empty cell name")));
+    }
+
     //  if the first cell is the dummy cell containing the context information
     //  read this cell in a special way and store the context information separately.
     if (first_cell && m_cellname == "$$$CONTEXT_INFO$$$") {
diff --git a/src/plugins/tools/diff/lay_plugin/DiffToolDialog.ui b/src/plugins/tools/diff/lay_plugin/DiffToolDialog.ui
index a14df4d1a..1995401fc 100644
--- a/src/plugins/tools/diff/lay_plugin/DiffToolDialog.ui
+++ b/src/plugins/tools/diff/lay_plugin/DiffToolDialog.ui
@@ -1,76 +1,73 @@
-<ui version="4.0" >
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
  <class>DiffToolDialog</class>
- <widget class="QDialog" name="DiffToolDialog" >
-  <property name="geometry" >
+ <widget class="QDialog" name="DiffToolDialog">
+  <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>498</width>
+    <width>503</width>
     <height>404</height>
    </rect>
   </property>
-  <property name="windowTitle" >
+  <property name="windowTitle">
    <string>Diff Tool</string>
   </property>
-  <layout class="QVBoxLayout" >
-   <property name="margin" >
-    <number>9</number>
-   </property>
-   <property name="spacing" >
+  <layout class="QVBoxLayout">
+   <property name="spacing">
     <number>6</number>
    </property>
+   <property name="margin" stdset="0">
+    <number>9</number>
+   </property>
    <item>
-    <widget class="QGroupBox" name="groupBox" >
-     <property name="title" >
+    <widget class="QGroupBox" name="groupBox">
+     <property name="title">
       <string>Input</string>
      </property>
-     <layout class="QGridLayout" >
-      <property name="margin" >
+     <layout class="QGridLayout">
+      <property name="margin" stdset="0">
        <number>9</number>
       </property>
-      <property name="spacing" >
+      <property name="spacing">
        <number>6</number>
       </property>
-      <item row="0" column="0" >
-       <widget class="QLabel" name="label" >
-        <property name="text" >
+      <item row="0" column="0">
+       <widget class="QLabel" name="label">
+        <property name="text">
          <string>Layout A   </string>
         </property>
        </widget>
       </item>
-      <item row="1" column="0" >
-       <widget class="QLabel" name="label_2" >
-        <property name="text" >
+      <item row="1" column="0">
+       <widget class="QLabel" name="label_2">
+        <property name="text">
          <string>Layout B</string>
         </property>
        </widget>
       </item>
-      <item row="0" column="1" >
-       <widget class="lay::CellViewSelectionComboBox" name="layouta" >
-        <property name="sizePolicy" >
-         <sizepolicy>
-          <hsizetype>7</hsizetype>
-          <vsizetype>5</vsizetype>
+      <item row="0" column="1">
+       <widget class="lay::CellViewSelectionComboBox" name="layouta">
+        <property name="sizePolicy">
+         <sizepolicy hsizetype="Expanding" vsizetype="Preferred">
           <horstretch>0</horstretch>
           <verstretch>0</verstretch>
          </sizepolicy>
         </property>
-        <property name="sizeAdjustPolicy" >
+        <property name="sizeAdjustPolicy">
          <enum>QComboBox::AdjustToContentsOnFirstShow</enum>
         </property>
        </widget>
       </item>
-      <item row="1" column="1" >
-       <widget class="lay::CellViewSelectionComboBox" name="layoutb" >
-        <property name="sizePolicy" >
-         <sizepolicy>
-          <hsizetype>7</hsizetype>
-          <vsizetype>5</vsizetype>
+      <item row="1" column="1">
+       <widget class="lay::CellViewSelectionComboBox" name="layoutb">
+        <property name="sizePolicy">
+         <sizepolicy hsizetype="Expanding" vsizetype="Preferred">
           <horstretch>0</horstretch>
           <verstretch>0</verstretch>
          </sizepolicy>
         </property>
-        <property name="sizeAdjustPolicy" >
+        <property name="sizeAdjustPolicy">
          <enum>QComboBox::AdjustToContentsOnFirstShow</enum>
         </property>
        </widget>
@@ -79,77 +76,84 @@
     </widget>
    </item>
    <item>
-    <widget class="QGroupBox" name="groupBox_2" >
-     <property name="title" >
+    <widget class="QGroupBox" name="groupBox_2">
+     <property name="title">
       <string>Options</string>
      </property>
-     <layout class="QVBoxLayout" >
-      <property name="margin" >
-       <number>9</number>
-      </property>
-      <property name="spacing" >
+     <layout class="QVBoxLayout">
+      <property name="spacing">
        <number>6</number>
       </property>
+      <property name="margin" stdset="0">
+       <number>9</number>
+      </property>
       <item>
-       <widget class="QCheckBox" name="smart_cbx" >
-        <property name="text" >
+       <widget class="QCheckBox" name="smart_cbx">
+        <property name="text">
          <string>Don't use names to match cells (use geometrical properties)</string>
         </property>
-        <property name="checked" >
+        <property name="checked">
          <bool>true</bool>
         </property>
        </widget>
       </item>
       <item>
-       <widget class="QCheckBox" name="xor_cbx" >
-        <property name="text" >
+       <widget class="QCheckBox" name="xor_cbx">
+        <property name="text">
          <string>Run XOR on differences</string>
         </property>
        </widget>
       </item>
       <item>
-       <widget class="QCheckBox" name="summarize_cbx" >
-        <property name="text" >
+       <widget class="QCheckBox" name="summarize_cbx">
+        <property name="text">
          <string>Summarize missing layers</string>
         </property>
-        <property name="checked" >
+        <property name="checked">
          <bool>true</bool>
         </property>
        </widget>
       </item>
       <item>
-       <widget class="QCheckBox" name="detailed_cbx" >
-        <property name="text" >
+       <widget class="QCheckBox" name="detailed_cbx">
+        <property name="text">
          <string>Detailed information</string>
         </property>
-        <property name="checked" >
+        <property name="checked">
          <bool>true</bool>
         </property>
        </widget>
       </item>
       <item>
-       <widget class="QCheckBox" name="expand_cell_arrays_cbx" >
-        <property name="text" >
+       <widget class="QCheckBox" name="expand_cell_arrays_cbx">
+        <property name="text">
          <string>Expand cell arrays (compare single instance by instance)</string>
         </property>
        </widget>
       </item>
       <item>
-       <widget class="QCheckBox" name="exact_cbx" >
-        <property name="text" >
+       <widget class="QCheckBox" name="exact_cbx">
+        <property name="text">
          <string>Exact compare (includes properties, text orientation and similar)</string>
         </property>
        </widget>
       </item>
+      <item>
+       <widget class="QCheckBox" name="ignore_duplicates_cbx">
+        <property name="text">
+         <string>Ignore duplicate instances and shapes</string>
+        </property>
+       </widget>
+      </item>
      </layout>
     </widget>
    </item>
    <item>
     <spacer>
-     <property name="orientation" >
+     <property name="orientation">
       <enum>Qt::Vertical</enum>
      </property>
-     <property name="sizeHint" >
+     <property name="sizeHint" stdset="0">
       <size>
        <width>472</width>
        <height>16</height>
@@ -158,12 +162,12 @@
     </spacer>
    </item>
    <item>
-    <widget class="QDialogButtonBox" name="buttonBox" >
-     <property name="orientation" >
+    <widget class="QDialogButtonBox" name="buttonBox">
+     <property name="orientation">
       <enum>Qt::Horizontal</enum>
      </property>
-     <property name="standardButtons" >
-      <set>QDialogButtonBox::Cancel|QDialogButtonBox::NoButton|QDialogButtonBox::Ok</set>
+     <property name="standardButtons">
+      <set>QDialogButtonBox::Cancel|QDialogButtonBox::Ok</set>
      </property>
     </widget>
    </item>
@@ -187,11 +191,11 @@
    <receiver>DiffToolDialog</receiver>
    <slot>accept()</slot>
    <hints>
-    <hint type="sourcelabel" >
+    <hint type="sourcelabel">
      <x>248</x>
      <y>254</y>
     </hint>
-    <hint type="destinationlabel" >
+    <hint type="destinationlabel">
      <x>157</x>
      <y>274</y>
     </hint>
@@ -203,11 +207,11 @@
    <receiver>DiffToolDialog</receiver>
    <slot>reject()</slot>
    <hints>
-    <hint type="sourcelabel" >
+    <hint type="sourcelabel">
      <x>316</x>
      <y>260</y>
     </hint>
-    <hint type="destinationlabel" >
+    <hint type="destinationlabel">
      <x>286</x>
      <y>274</y>
     </hint>
diff --git a/src/plugins/tools/diff/lay_plugin/layDiffToolDialog.cc b/src/plugins/tools/diff/lay_plugin/layDiffToolDialog.cc
index 1285f72bb..5ae9dcafb 100644
--- a/src/plugins/tools/diff/lay_plugin/layDiffToolDialog.cc
+++ b/src/plugins/tools/diff/lay_plugin/layDiffToolDialog.cc
@@ -46,6 +46,7 @@ std::string cfg_diff_smart ("diff-smart");
 std::string cfg_diff_summarize ("diff-summarize");
 std::string cfg_diff_expand_cell_arrays ("diff-expand-cell-arrays");
 std::string cfg_diff_exact ("diff-exact");
+std::string cfg_diff_ignore_duplicates ("diff-ignore-duplicates");
 
 // ------------------------------------------------------------------------------
 //  RdbDifferenceReceiver definition
@@ -650,6 +651,9 @@ DiffToolDialog::exec_dialog (lay::LayoutViewBase *view)
   if (config_root->config_get (cfg_diff_exact, f)) {
     mp_ui->exact_cbx->setChecked (f);
   }
+  if (config_root->config_get (cfg_diff_ignore_duplicates, f)) {
+    mp_ui->ignore_duplicates_cbx->setChecked (f);
+  }
 
   update ();
 
@@ -686,6 +690,7 @@ BEGIN_PROTECTED
   config_root->config_set (cfg_diff_summarize, mp_ui->summarize_cbx->isChecked ());
   config_root->config_set (cfg_diff_expand_cell_arrays, mp_ui->expand_cell_arrays_cbx->isChecked ());
   config_root->config_set (cfg_diff_exact, mp_ui->exact_cbx->isChecked ());
+  config_root->config_set (cfg_diff_ignore_duplicates, mp_ui->ignore_duplicates_cbx->isChecked ());
   config_root->config_end ();
 
   QDialog::accept ();
@@ -712,6 +717,7 @@ DiffToolDialog::run_diff ()
   bool summarize = !run_xor && mp_ui->summarize_cbx->isChecked ();
   bool expand_cell_arrays = !run_xor && mp_ui->expand_cell_arrays_cbx->isChecked ();
   bool exact = !run_xor && mp_ui->exact_cbx->isChecked ();
+  bool ignore_duplicates = mp_ui->ignore_duplicates_cbx->isChecked ();
 
   int cv_index_a = mp_ui->layouta->current_cv_index ();
   int cv_index_b = mp_ui->layoutb->current_cv_index ();
@@ -740,6 +746,9 @@ DiffToolDialog::run_diff ()
   if (smart) {
     flags |= db::layout_diff::f_smart_cell_mapping;
   }
+  if (ignore_duplicates) {
+    flags |= db::layout_diff::f_ignore_duplicates;
+  }
 
   //  TODO: make an parameter
   db::Coord tolerance = 0;
diff --git a/src/pya/pya/pya.cc b/src/pya/pya/pya.cc
index 53d0d9496..44f31d88a 100644
--- a/src/pya/pya/pya.cc
+++ b/src/pya/pya/pya.cc
@@ -34,6 +34,7 @@
 #include "gsiDecl.h"
 #include "gsiDeclBasic.h"
 #include "tlLog.h"
+#include "tlEnv.h"
 #include "tlStream.h"
 #include "tlTimer.h"
 #include "tlFileUtils.h"
@@ -140,6 +141,16 @@ public:
 
   virtual size_t scope_index () const
   {
+    static int consider_scope = -1;
+
+    //  disable scoped debugging (e.g. DRC script lines) if $KLAYOUT_PYA_DEBUG_SCOPE is set.
+    if (consider_scope < 0) {
+      consider_scope = tl::app_flag ("pya-debug-scope") ? 0 : 1;
+    }
+    if (! consider_scope) {
+      return 0;
+    }
+
     if (! m_scope.empty ()) {
       for (size_t i = 0; i < m_stack_trace.size (); ++i) {
         if (m_stack_trace [i].file == m_scope) {
diff --git a/src/rba/rba/rba.cc b/src/rba/rba/rba.cc
index 27af10ed0..00826361c 100644
--- a/src/rba/rba/rba.cc
+++ b/src/rba/rba/rba.cc
@@ -111,7 +111,7 @@ RubyStackTraceProvider::scope_index (const std::vector<tl::BacktraceElement> &bt
 
     //  disable scoped debugging (e.g. DRC script lines) if $KLAYOUT_RBA_DEBUG_SCOPE is set.
     if (consider_scope < 0) {
-      consider_scope = tl::has_env ("KLAYOUT_RBA_DEBUG_SCOPE") ? 0 : 1;
+      consider_scope = tl::app_flag ("rba-debug-scope") ? 0 : 1;
     }
     if (! consider_scope) {
       return 0;
diff --git a/testdata/algo/hlp18.oas b/testdata/algo/hlp18.oas
new file mode 100644
index 000000000..2c45f1226
Binary files /dev/null and b/testdata/algo/hlp18.oas differ
diff --git a/testdata/drc/drcSimpleTests_14b.drc b/testdata/drc/drcSimpleTests_14b.drc
new file mode 100644
index 000000000..0d4daa56a
--- /dev/null
+++ b/testdata/drc/drcSimpleTests_14b.drc
@@ -0,0 +1,24 @@
+
+source($drc_test_source)
+
+target($drc_test_target)
+
+l1 = input(1, 0)
+l2 = input(2, 0)
+
+tcopy = new_target($drc_test_target2)
+rcopy = new_report("Report 2", $drc_test_report2)
+
+l1.output(tcopy, 101, 0)
+l2.output(tcopy, 102, 0)
+
+l1.output(1, 0)
+l1.space(1.0.um).output(100, 0)
+
+report("Report 1", $drc_test_report)
+
+l2.space(1.0.um).output("l2 space < 1µm")
+l1.width(1.0.um).output("l1 width < 1µm")
+
+l1.sep(l2, 1.0.um).output(rcopy, "l1 sep l2 < 1µm")
+
diff --git a/testdata/drc/drcSimpleTests_14b.gds b/testdata/drc/drcSimpleTests_14b.gds
new file mode 100644
index 000000000..c43c2fae9
Binary files /dev/null and b/testdata/drc/drcSimpleTests_14b.gds differ
diff --git a/testdata/drc/drcSimpleTests_au14b.gds b/testdata/drc/drcSimpleTests_au14b.gds
new file mode 100644
index 000000000..af3ebbcfb
Binary files /dev/null and b/testdata/drc/drcSimpleTests_au14b.gds differ
diff --git a/testdata/drc/drcSimpleTests_au14b.lyrdb b/testdata/drc/drcSimpleTests_au14b.lyrdb
new file mode 100644
index 000000000..0b6c00a9d
--- /dev/null
+++ b/testdata/drc/drcSimpleTests_au14b.lyrdb
@@ -0,0 +1,88 @@
+<?xml version="1.0" encoding="utf-8"?>
+<report-database>
+ <description>Report 1</description>
+ <original-file/>
+ <generator>drc: script='.drc'</generator>
+ <top-cell>TOP</top-cell>
+ <tags>
+ </tags>
+ <categories>
+  <category>
+   <name>l2 space &lt; 1µm</name>
+   <description/>
+   <categories>
+   </categories>
+  </category>
+  <category>
+   <name>l1 width &lt; 1µm</name>
+   <description/>
+   <categories>
+   </categories>
+  </category>
+ </categories>
+ <cells>
+  <cell>
+   <name>TOP</name>
+   <variant/>
+   <references>
+   </references>
+  </cell>
+ </cells>
+ <items>
+  <item>
+   <tags/>
+   <category>'l2 space &lt; 1\302\265m'</category>
+   <cell>TOP</cell>
+   <visited>false</visited>
+   <multiplicity>1</multiplicity>
+   <image/>
+   <values>
+    <value>edge-pair: (-0.2,0.7;1,0.7)|(1,1.1;-0.2,1.1)</value>
+   </values>
+  </item>
+  <item>
+   <tags/>
+   <category>'l1 width &lt; 1\302\265m'</category>
+   <cell>TOP</cell>
+   <visited>false</visited>
+   <multiplicity>1</multiplicity>
+   <image/>
+   <values>
+    <value>edge-pair: (0,0;0,0.9)|(0.3,0.9;0.3,0)</value>
+   </values>
+  </item>
+  <item>
+   <tags/>
+   <category>'l1 width &lt; 1\302\265m'</category>
+   <cell>TOP</cell>
+   <visited>false</visited>
+   <multiplicity>1</multiplicity>
+   <image/>
+   <values>
+    <value>edge-pair: (0.3,0;0,0)|(0,0.9;0.3,0.9)</value>
+   </values>
+  </item>
+  <item>
+   <tags/>
+   <category>'l1 width &lt; 1\302\265m'</category>
+   <cell>TOP</cell>
+   <visited>false</visited>
+   <multiplicity>1</multiplicity>
+   <image/>
+   <values>
+    <value>edge-pair: (0.5,0;0.5,0.9)|(0.8,0.9;0.8,0)</value>
+   </values>
+  </item>
+  <item>
+   <tags/>
+   <category>'l1 width &lt; 1\302\265m'</category>
+   <cell>TOP</cell>
+   <visited>false</visited>
+   <multiplicity>1</multiplicity>
+   <image/>
+   <values>
+    <value>edge-pair: (0.8,0;0.5,0)|(0.5,0.9;0.8,0.9)</value>
+   </values>
+  </item>
+ </items>
+</report-database>
diff --git a/testdata/drc/drcSimpleTests_au14b_2.gds b/testdata/drc/drcSimpleTests_au14b_2.gds
new file mode 100644
index 000000000..b3a512645
Binary files /dev/null and b/testdata/drc/drcSimpleTests_au14b_2.gds differ
diff --git a/testdata/drc/drcSimpleTests_au14b_2.lyrdb b/testdata/drc/drcSimpleTests_au14b_2.lyrdb
new file mode 100644
index 000000000..f3430532f
--- /dev/null
+++ b/testdata/drc/drcSimpleTests_au14b_2.lyrdb
@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="utf-8"?>
+<report-database>
+ <description>Report 2</description>
+ <original-file/>
+ <generator>drc: script='.drc'</generator>
+ <top-cell>TOP</top-cell>
+ <tags>
+ </tags>
+ <categories>
+  <category>
+   <name>l1 sep l2 &lt; 1µm</name>
+   <description/>
+   <categories>
+   </categories>
+  </category>
+ </categories>
+ <cells>
+  <cell>
+   <name>TOP</name>
+   <variant/>
+   <references>
+   </references>
+  </cell>
+ </cells>
+ <items>
+  <item>
+   <tags/>
+   <category>'l1 sep l2 &lt; 1\302\265m'</category>
+   <cell>TOP</cell>
+   <visited>false</visited>
+   <multiplicity>1</multiplicity>
+   <image/>
+   <values>
+    <value>edge-pair: (0,0.9;0.3,0.9)/(1,1.1;-0.2,1.1)</value>
+   </values>
+  </item>
+  <item>
+   <tags/>
+   <category>'l1 sep l2 &lt; 1\302\265m'</category>
+   <cell>TOP</cell>
+   <visited>false</visited>
+   <multiplicity>1</multiplicity>
+   <image/>
+   <values>
+    <value>edge-pair: (0.5,0.9;0.8,0.9)/(1,1.1;-0.2,1.1)</value>
+   </values>
+  </item>
+ </items>
+</report-database>
diff --git a/testdata/pymod/import_db.py b/testdata/pymod/import_db.py
index 2c1881260..154bd7198 100755
--- a/testdata/pymod/import_db.py
+++ b/testdata/pymod/import_db.py
@@ -41,6 +41,12 @@ class BasicTest(unittest.TestCase):
     v.read(os.path.join(os.path.dirname(__file__), "..", "gds", "t10.gds"))
     self.assertEqual(v.top_cell().name, "RINGO")
 
+  def test_4(self):
+    # gds2_text plugin loaded? (issue #1393)
+    v = db.Layout()
+    v.read(os.path.join(os.path.dirname(__file__), "..", "gds2_txt", "read.txt"))
+    self.assertEqual(v.top_cell().name, "RINGO")
+
 # run unit tests
 if __name__ == '__main__':
   suite = unittest.TestSuite()
diff --git a/testdata/ruby/dbLayoutTests1.rb b/testdata/ruby/dbLayoutTests1.rb
index dca1b4b8b..c6734efb3 100644
--- a/testdata/ruby/dbLayoutTests1.rb
+++ b/testdata/ruby/dbLayoutTests1.rb
@@ -1971,6 +1971,66 @@ class DBLayoutTests1_TestClass < TestBase
 
   end
 
+  def test_23
+
+    # layer operations with shape types
+   
+    m = RBA::Manager::new
+
+    l = RBA::Layout.new(m)
+    l1 = l.insert_layer(RBA::LayerInfo.new(1, 0))
+    l2 = l.insert_layer(RBA::LayerInfo.new(2, 0))
+    c0 = l.cell(l.add_cell("c0"))
+    c1 = l.cell(l.add_cell("c1"))
+  
+    c0.shapes(l1).insert(RBA::Box::new(1, 2, 3, 4))
+    c1.shapes(l1).insert(RBA::Polygon::new(RBA::Box::new(1, 2, 3, 4)))
+
+    str1 = l.each_cell.collect { |c| c.name + ":" + c.shapes(l1).each.collect { |sh| sh.to_s }.join(";") }.join("\n")
+    assert_equal(str1, "c0:box (1,2;3,4)\nc1:polygon (1,2;1,4;3,4;3,2)")
+
+    m.transaction("T")
+    l.clear_layer(l1, RBA::Shapes::SPolygons)
+    m.commit
+
+    str1 = l.each_cell.collect { |c| c.name + ":" + c.shapes(l1).each.collect { |sh| sh.to_s }.join(";") }.join("\n")
+    assert_equal(str1, "c0:box (1,2;3,4)\nc1:")
+
+    m.undo 
+
+    str1 = l.each_cell.collect { |c| c.name + ":" + c.shapes(l1).each.collect { |sh| sh.to_s }.join(";") }.join("\n")
+    assert_equal(str1, "c0:box (1,2;3,4)\nc1:polygon (1,2;1,4;3,4;3,2)")
+
+    m.transaction("T")
+    l.move_layer(l1, l2, RBA::Shapes::SPolygons)
+    m.commit
+
+    str1 = l.each_cell.collect { |c| c.name + ":" + c.shapes(l1).each.collect { |sh| sh.to_s }.join(";") }.join("\n")
+    assert_equal(str1, "c0:box (1,2;3,4)\nc1:")
+
+    str2 = l.each_cell.collect { |c| c.name + ":" + c.shapes(l2).each.collect { |sh| sh.to_s }.join(";") }.join("\n")
+    assert_equal(str2, "c0:\nc1:polygon (1,2;1,4;3,4;3,2)")
+
+    m.undo 
+
+    str1 = l.each_cell.collect { |c| c.name + ":" + c.shapes(l1).each.collect { |sh| sh.to_s }.join(";") }.join("\n")
+    assert_equal(str1, "c0:box (1,2;3,4)\nc1:polygon (1,2;1,4;3,4;3,2)")
+
+    str2 = l.each_cell.collect { |c| c.name + ":" + c.shapes(l2).each.collect { |sh| sh.to_s }.join(";") }.join("\n")
+    assert_equal(str2, "c0:\nc1:")
+
+    m.transaction("T")
+    l.copy_layer(l1, l2, RBA::Shapes::SPolygons)
+    m.commit
+
+    str1 = l.each_cell.collect { |c| c.name + ":" + c.shapes(l1).each.collect { |sh| sh.to_s }.join(";") }.join("\n")
+    assert_equal(str1, "c0:box (1,2;3,4)\nc1:polygon (1,2;1,4;3,4;3,2)")
+
+    str2 = l.each_cell.collect { |c| c.name + ":" + c.shapes(l2).each.collect { |sh| sh.to_s }.join(";") }.join("\n")
+    assert_equal(str2, "c0:\nc1:polygon (1,2;1,4;3,4;3,2)")
+
+  end
+
   # Iterating while flatten
   def test_issue200
 
diff --git a/testdata/ruby/dbShapesTest.rb b/testdata/ruby/dbShapesTest.rb
index 76bb1df85..a55ffa4f8 100644
--- a/testdata/ruby/dbShapesTest.rb
+++ b/testdata/ruby/dbShapesTest.rb
@@ -1595,6 +1595,34 @@ class DBShapes_TestClass < TestBase
 
   end
 
+  # Shapes with shape-type specific insert and clear
+  def test_11
+
+    s = RBA::Shapes::new
+    s.insert(RBA::Box::new(1, 2, 3, 4))
+    s.insert(RBA::Polygon::new(RBA::Box::new(1, 2, 3, 4)))
+
+    assert_equal(s.each.collect { |sh| sh.to_s }.join("; "), "polygon (1,2;1,4;3,4;3,2); box (1,2;3,4)")
+
+    s2 = RBA::Shapes::new
+    s2.insert(s)
+
+    assert_equal(s2.each.collect { |sh| sh.to_s }.join("; "), "polygon (1,2;1,4;3,4;3,2); box (1,2;3,4)")
+
+    s2.clear(RBA::Shapes::SPolygons)
+
+    assert_equal(s2.each.collect { |sh| sh.to_s }.join("; "), "box (1,2;3,4)")
+
+    s2.clear
+    
+    assert_equal(s2.each.collect { |sh| sh.to_s }.join("; "), "")
+
+    s2.insert(s, RBA::Shapes::SPolygons)
+
+    assert_equal(s2.each.collect { |sh| sh.to_s }.join("; "), "polygon (1,2;1,4;3,4;3,2)")
+
+  end
+
 end
 
 load("test_epilogue.rb")