diff --git a/src/db/db/dbCompoundOperation.cc b/src/db/db/dbCompoundOperation.cc
index d5df599f4..272fa0181 100644
--- a/src/db/db/dbCompoundOperation.cc
+++ b/src/db/db/dbCompoundOperation.cc
@@ -1,4 +1,25 @@
 
+/*
+
+  KLayout Layout Viewer
+  Copyright (C) 2006-2020 Matthias Koefferlein
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+*/
+
 #include "dbCompoundOperation.h"
 #include "dbRegion.h"
 
@@ -25,6 +46,18 @@ namespace db
 
 // ---------------------------------------------------------------------------------------------
 
+CompoundRegionOperationNode::CompoundRegionOperationNode ()
+{
+  invalidate_cache ();
+}
+
+CompoundRegionOperationNode::~CompoundRegionOperationNode ()
+{
+  // .. nothing yet ..
+}
+
+// ---------------------------------------------------------------------------------------------
+
 void
 CompoundRegionOperationNode::compute_local (db::Layout *layout, const shape_interactions<db::Polygon, db::Polygon> &interactions, std::vector<std::unordered_set<db::PolygonRef> > &results, size_t max_vertex_count, double area_ratio) const
 {
@@ -61,6 +94,16 @@ CompoundRegionOperationPrimaryNode::CompoundRegionOperationPrimaryNode ()
   //  .. nothing yet ..
 }
 
+CompoundRegionOperationPrimaryNode::~CompoundRegionOperationPrimaryNode ()
+{
+  //  .. nothing yet ..
+}
+
+std::string CompoundRegionOperationPrimaryNode::description () const
+{
+  return std::string ("this");
+}
+
 std::vector<db::Region *> CompoundRegionOperationPrimaryNode::inputs () const
 {
   return std::vector<db::Region *> ();
@@ -88,6 +131,16 @@ CompoundRegionOperationSecondaryNode::CompoundRegionOperationSecondaryNode (db::
   //  .. nothing yet ..
 }
 
+CompoundRegionOperationSecondaryNode::~CompoundRegionOperationSecondaryNode ()
+{
+  //  .. nothing yet ..
+}
+
+std::string CompoundRegionOperationSecondaryNode::description () const
+{
+  return std::string ("other");
+}
+
 std::vector<db::Region *> CompoundRegionOperationSecondaryNode::inputs () const
 {
   std::vector<db::Region *> iv;
@@ -949,3 +1002,4 @@ CompoundRegionToEdgePairProcessingOperationNode::processed (db::Layout *, const
 }
 
 }
+
diff --git a/src/db/db/dbCompoundOperation.h b/src/db/db/dbCompoundOperation.h
index f5e4cbf1c..d5874058b 100644
--- a/src/db/db/dbCompoundOperation.h
+++ b/src/db/db/dbCompoundOperation.h
@@ -23,6 +23,7 @@
 #ifndef HDR_dbCompoundOperation
 #define HDR_dbCompoundOperation
 
+#include "dbCommon.h"
 #include "dbLocalOperation.h"
 #include "dbHierProcessor.h"
 #include "dbRegionDelegate.h"
@@ -46,12 +47,8 @@ class DB_PUBLIC CompoundRegionOperationNode
 public:
   enum  ResultType { Region, Edges, EdgePairs };
 
-  CompoundRegionOperationNode ()
-  {
-    invalidate_cache ();
-  }
-
-  virtual ~CompoundRegionOperationNode () { }
+  CompoundRegionOperationNode ();
+  virtual ~CompoundRegionOperationNode ();
 
   virtual db::Coord dist () const = 0;
   virtual std::string description () const = 0;
@@ -221,10 +218,12 @@ class DB_PUBLIC CompoundRegionOperationPrimaryNode
 {
 public:
   CompoundRegionOperationPrimaryNode ();
+  virtual ~CompoundRegionOperationPrimaryNode ();
 
   virtual std::string description () const;
-
   virtual std::vector<db::Region *> inputs () const;
+  virtual db::Coord dist () const { return 0; }
+  virtual ResultType result_type () const { return Region; }
 
   virtual void do_compute_local (db::Layout *layout, const shape_interactions<db::Polygon, db::Polygon> &interactions, std::vector<std::unordered_set<db::Polygon> > &results, size_t max_vertex_count, double area_ratio) const;
   virtual void do_compute_local (db::Layout *layout, const shape_interactions<db::PolygonRef, db::PolygonRef> &interactions, std::vector<std::unordered_set<db::PolygonRef> > &results, size_t max_vertex_count, double area_ratio) const;
@@ -236,10 +235,12 @@ class DB_PUBLIC CompoundRegionOperationSecondaryNode
 {
 public:
   CompoundRegionOperationSecondaryNode (db::Region *input);
+  virtual ~CompoundRegionOperationSecondaryNode ();
 
   virtual std::string description () const;
-
   virtual std::vector<db::Region *> inputs () const;
+  virtual db::Coord dist () const { return 0; }
+  virtual ResultType result_type () const { return Region; }
 
   virtual void do_compute_local (db::Layout *layout, const shape_interactions<db::Polygon, db::Polygon> &interactions, std::vector<std::unordered_set<db::Polygon> > &results, size_t max_vertex_count, double area_ratio) const;
   virtual void do_compute_local (db::Layout *layout, const shape_interactions<db::PolygonRef, db::PolygonRef> &interactions, std::vector<std::unordered_set<db::PolygonRef> > &results, size_t max_vertex_count, double area_ratio) const;