diff --git a/src/db/db/dbAsIfFlatEdges.cc b/src/db/db/dbAsIfFlatEdges.cc
index f370532e0..0f09068b5 100644
--- a/src/db/db/dbAsIfFlatEdges.cc
+++ b/src/db/db/dbAsIfFlatEdges.cc
@@ -743,9 +743,17 @@ AsIfFlatEdges::filtered_pair (const EdgeFilterBase &filter) const
 
   for (EdgesIterator p (begin_merged ()); ! p.at_end (); ++p) {
     if (filter.selected (*p, p.prop_id ())) {
-      new_region_true->insert (*p);
+      if (p.prop_id () != 0) {
+        new_region_true->insert (db::EdgeWithProperties (*p, p.prop_id ()));
+      } else {
+        new_region_true->insert (*p);
+      }
     } else {
-      new_region_false->insert (*p);
+      if (p.prop_id () != 0) {
+        new_region_false->insert (db::EdgeWithProperties (*p, p.prop_id ()));
+      } else {
+        new_region_false->insert (*p);
+      }
     }
   }
 
diff --git a/src/db/db/dbAsIfFlatRegion.cc b/src/db/db/dbAsIfFlatRegion.cc
index 8747324ff..56e5d608b 100644
--- a/src/db/db/dbAsIfFlatRegion.cc
+++ b/src/db/db/dbAsIfFlatRegion.cc
@@ -526,9 +526,17 @@ AsIfFlatRegion::filtered_pair (const PolygonFilterBase &filter) const
 
   for (RegionIterator p (begin_merged ()); ! p.at_end (); ++p) {
     if (filter.selected (*p, p.prop_id ())) {
-      new_region_true->insert (*p);
+      if (p.prop_id () != 0) {
+        new_region_true->insert (db::PolygonWithProperties (*p, p.prop_id ()));
+      } else {
+        new_region_true->insert (*p);
+      }
     } else {
-      new_region_false->insert (*p);
+      if (p.prop_id () != 0) {
+        new_region_false->insert (db::PolygonWithProperties (*p, p.prop_id ()));
+      } else {
+        new_region_false->insert (*p);
+      }
     }
   }
 
diff --git a/src/db/db/dbAsIfFlatTexts.cc b/src/db/db/dbAsIfFlatTexts.cc
index d4fe8cad8..f8dd3e086 100644
--- a/src/db/db/dbAsIfFlatTexts.cc
+++ b/src/db/db/dbAsIfFlatTexts.cc
@@ -179,9 +179,17 @@ AsIfFlatTexts::filtered_pair (const TextFilterBase &filter) const
 
   for (TextsIterator p (begin ()); ! p.at_end (); ++p) {
     if (filter.selected (*p, p.prop_id ())) {
-      new_texts_true->insert (*p);
+      if (p.prop_id () != 0) {
+        new_texts_true->insert (db::TextWithProperties (*p, p.prop_id ()));
+      } else {
+        new_texts_true->insert (*p);
+      }
     } else {
-      new_texts_false->insert (*p);
+      if (p.prop_id () != 0) {
+        new_texts_false->insert (db::TextWithProperties (*p, p.prop_id ()));
+      } else {
+        new_texts_false->insert (*p);
+      }
     }
   }
 
diff --git a/src/db/db/dbLayoutToNetlist.cc b/src/db/db/dbLayoutToNetlist.cc
index 856e889cc..6c26ae12f 100644
--- a/src/db/db/dbLayoutToNetlist.cc
+++ b/src/db/db/dbLayoutToNetlist.cc
@@ -2105,12 +2105,18 @@ LayoutToNetlist::measure_net (const db::Region &primary, const std::map<std::str
         continue;
       }
 
-      eval.reset (*cid, *c);
-      compiled_expr.execute ();
+      try {
 
-      if (! eval.skip ()) {
-        db::Shapes &shapes = ly.cell (*cid).shapes (dl.layer ());
-        get_merged_shapes_of_net (*cid, *c, primary_layer, shapes, db::properties_id (eval.prop_set_out ()));
+        eval.reset (*cid, *c);
+        compiled_expr.execute ();
+
+        if (! eval.skip ()) {
+          db::Shapes &shapes = ly.cell (*cid).shapes (dl.layer ());
+          get_merged_shapes_of_net (*cid, *c, primary_layer, shapes, db::properties_id (eval.prop_set_out ()));
+        }
+
+      } catch (tl::Exception &ex) {
+        tl::warn << ex.msg ();
       }
 
     }
diff --git a/src/db/db/dbMeasureEval.cc b/src/db/db/dbMeasureEval.cc
index e2288934c..eaa73a8d3 100644
--- a/src/db/db/dbMeasureEval.cc
+++ b/src/db/db/dbMeasureEval.cc
@@ -51,6 +51,28 @@ private:
   MeasureEval *mp_eval;
 };
 
+class SkipFunction
+  : public tl::EvalFunction
+{
+public:
+  SkipFunction (MeasureEval *eval)
+    : mp_eval (eval)
+  {
+    //  .. nothing yet ..
+  }
+
+  virtual void execute (const tl::ExpressionParserContext &context, tl::Variant & /*out*/, const std::vector<tl::Variant> &args, const std::map<std::string, tl::Variant> * /*kwargs*/) const
+  {
+    if (args.size () != 1) {
+      throw tl::EvalError (tl::to_string (tr ("'skip' function takes one argument (flag)")), context);
+    }
+    mp_eval->skip_func (args [0].to_bool ());
+  }
+
+private:
+  MeasureEval *mp_eval;
+};
+
 class ValueFunction
   : public tl::EvalFunction
 {
@@ -144,7 +166,7 @@ private:
 //  MeasureEval implementation
 
 MeasureEval::MeasureEval (double dbu, bool with_put)
-  : m_shape_type (None), m_prop_id (0), m_dbu (dbu), m_with_put (with_put)
+  : m_shape_type (None), m_prop_id (0), m_skip (false), m_dbu (dbu), m_with_put (with_put)
 {
   mp_shape.any = 0;
 }
@@ -154,6 +176,7 @@ MeasureEval::init ()
 {
   if (m_with_put) {
     define_function ("put", new PutFunction (this));
+    define_function ("skip", new SkipFunction (this));
   }
 
   define_function ("shape", new ShapeFunction (this));
@@ -161,14 +184,6 @@ MeasureEval::init ()
   define_function ("values", new ValuesFunction (this));
 }
 
-void
-MeasureEval::reset_shape () const
-{
-  m_shape_type = None;
-  mp_shape.any = 0;
-  m_prop_id = 0;
-}
-
 void
 MeasureEval::set_shape (const db::Polygon *poly) const
 {
@@ -205,9 +220,10 @@ MeasureEval::set_shape (const db::Text *text) const
 }
 
 void
-MeasureEval::set_prop_id (db::properties_id_type prop_id) const
+MeasureEval::reset (db::properties_id_type prop_id) const
 {
   m_prop_id = prop_id;
+  m_skip = false;
 }
 
 void
@@ -223,6 +239,12 @@ MeasureEval::resolve_name (const std::string &name, const tl::EvalFunction *&fun
   }
 }
 
+void
+MeasureEval::skip_func (bool f) const
+{
+  m_skip = f;
+}
+
 tl::Variant
 MeasureEval::shape_func () const
 {
diff --git a/src/db/db/dbMeasureEval.h b/src/db/db/dbMeasureEval.h
index aaf899138..0abbc0140 100644
--- a/src/db/db/dbMeasureEval.h
+++ b/src/db/db/dbMeasureEval.h
@@ -49,13 +49,17 @@ public:
 
   void init ();
 
-  void reset_shape () const;
+  void reset (db::properties_id_type prop_id) const;
   void set_shape (const db::Polygon *poly) const;
   void set_shape (const db::PolygonRef *poly) const;
   void set_shape (const db::Edge *edge) const;
   void set_shape (const db::EdgePair *edge_pair) const;
   void set_shape (const db::Text *text) const;
-  void set_prop_id (db::properties_id_type prop_id) const;
+
+  bool skip () const
+  {
+    return m_skip;
+  }
 
   db::PropertiesSet &prop_set_out () const
   {
@@ -67,6 +71,7 @@ protected:
 
 private:
   friend class ShapeFunction;
+  friend class SkipFunction;
   friend class ValueFunction;
   friend class ValuesFunction;
   friend class PropertyFunction;
@@ -95,6 +100,7 @@ private:
   mutable ShapeType m_shape_type;
   mutable ShapeRef mp_shape;
   mutable db::properties_id_type m_prop_id;
+  mutable bool m_skip;
   mutable db::PropertiesSet m_prop_set_out;
   double m_dbu;
   bool m_with_put;
@@ -104,6 +110,7 @@ private:
   tl::Variant value_func (const tl::Variant &name) const;
   tl::Variant values_func (const tl::Variant &name) const;
   void put_func (const tl::Variant &name, const tl::Variant &value) const;
+  void skip_func (bool f) const;
 };
 
 /**
diff --git a/src/db/db/gsiDeclDbEdgePairs.cc b/src/db/db/gsiDeclDbEdgePairs.cc
index b5c6c4747..3c83fe30c 100644
--- a/src/db/db/gsiDeclDbEdgePairs.cc
+++ b/src/db/db/gsiDeclDbEdgePairs.cc
@@ -300,13 +300,14 @@ Class<property_computation_processor<db::EdgePairProcessorBase, db::EdgePairs> >
   "is attached to the output edge pairs as user properties with the given names.\n"
   "\n"
   "Alternatively, a single expression can be given. In that case, 'put' needs to be used to attach properties "
-  "to the output shape.\n"
+  "to the output shape. You can also use 'skip' to drop shapes in that case.\n"
   "\n"
   "The expression may use the following variables and functions:\n"
   "\n"
   "@ul\n"
   "@li @b shape @/b: The current shape (i.e. 'EdgePair' without DBU specified or 'DEdgePair' otherwise) @/li\n"
   "@li @b put(<name>, <value>) @/b: Attaches the given value as a property with name 'name' to the output shape @/li\n"
+  "@li @b skip(<flag>) @/b: If called with a 'true' value, the shape is dropped from the output @/li\n"
   "@li @b value(<name>) @/b: The value of the property with the given name (the first one if there are multiple properties with the same name) @/li\n"
   "@li @b values(<name>) @/b: All values of the properties with the given name (returns a list) @/li\n"
   "@li @b <name> @/b: A shortcut for 'value(<name>)' (<name> is used as a symbol) @/li\n"
diff --git a/src/db/db/gsiDeclDbEdges.cc b/src/db/db/gsiDeclDbEdges.cc
index 9a98cfb89..109101272 100644
--- a/src/db/db/gsiDeclDbEdges.cc
+++ b/src/db/db/gsiDeclDbEdges.cc
@@ -305,13 +305,14 @@ Class<property_computation_processor<db::EdgeProcessorBase, db::Edges> > decl_Ed
   "is attached to the output edge pairs as user properties with the given names.\n"
   "\n"
   "Alternatively, a single expression can be given. In that case, 'put' needs to be used to attach properties "
-  "to the output shape.\n"
+  "to the output shape. You can also use 'skip' to drop shapes in that case.\n"
   "\n"
   "The expression may use the following variables and functions:\n"
   "\n"
   "@ul\n"
   "@li @b shape @/b: The current shape (i.e. 'Edge' without DBU specified or 'DEdge' otherwise) @/li\n"
   "@li @b put(<name>, <value>) @/b: Attaches the given value as a property with name 'name' to the output shape @/li\n"
+  "@li @b skip(<flag>) @/b: If called with a 'true' value, the shape is dropped from the output @/li\n"
   "@li @b value(<name>) @/b: The value of the property with the given name (the first one if there are multiple properties with the same name) @/li\n"
   "@li @b values(<name>) @/b: All values of the properties with the given name (returns a list) @/li\n"
   "@li @b <name> @/b: A shortcut for 'value(<name>)' (<name> is used as a symbol) @/li\n"
diff --git a/src/db/db/gsiDeclDbMeasureHelpers.h b/src/db/db/gsiDeclDbMeasureHelpers.h
index d31445288..80bc65bdf 100644
--- a/src/db/db/gsiDeclDbMeasureHelpers.h
+++ b/src/db/db/gsiDeclDbMeasureHelpers.h
@@ -121,36 +121,44 @@ public:
 
   virtual void process (const db::object_with_properties<shape_type> &shape, std::vector<db::object_with_properties<shape_type> > &res) const
   {
-    res.push_back (shape);
+    try {
 
-    m_eval.set_prop_id (shape.properties_id ());
-    m_eval.set_shape (&shape);
+      m_eval.reset (shape.properties_id ());
+      m_eval.set_shape (&shape);
+
+      db::PropertiesSet &ps_out = m_eval.prop_set_out ();
+      if (m_copy_properties) {
+        ps_out = db::properties (shape.properties_id ());
+        for (auto e = m_expressions.begin (); e != m_expressions.end (); ++e) {
+          if (e->first != db::property_names_id_type (0)) {
+            ps_out.erase (e->first);
+          }
+        }
+      } else {
+        ps_out.clear ();
+      }
 
-    db::PropertiesSet &ps_out = m_eval.prop_set_out ();
-    if (m_copy_properties) {
-      ps_out = db::properties (shape.properties_id ());
       for (auto e = m_expressions.begin (); e != m_expressions.end (); ++e) {
         if (e->first != db::property_names_id_type (0)) {
-          ps_out.erase (e->first);
+          ps_out.insert (e->first, e->second.execute ());
         }
       }
-    } else {
-      ps_out.clear ();
-    }
 
-    for (auto e = m_expressions.begin (); e != m_expressions.end (); ++e) {
-      if (e->first != db::property_names_id_type (0)) {
-        ps_out.insert (e->first, e->second.execute ());
+      for (auto e = m_expressions.begin (); e != m_expressions.end (); ++e) {
+        if (e->first == db::property_names_id_type (0)) {
+          e->second.execute ();
+        }
       }
-    }
 
-    for (auto e = m_expressions.begin (); e != m_expressions.end (); ++e) {
-      if (e->first == db::property_names_id_type (0)) {
-        e->second.execute ();
+      if (! m_eval.skip ()) {
+        res.push_back (shape);
+        res.back ().properties_id (db::properties_id (ps_out));
       }
-    }
 
-    res.back ().properties_id (db::properties_id (ps_out));
+    } catch (tl::Exception &ex) {
+      tl::warn << ex.msg ();
+      res.clear ();
+    }
   }
 
 public:
@@ -190,21 +198,35 @@ public:
 
   virtual bool selected (const shape_type &shape, db::properties_id_type prop_id) const
   {
-    m_eval.set_prop_id (prop_id);
-    m_eval.set_shape (&shape);
+    try {
 
-    bool res = m_expression.execute ().to_bool ();
-    return m_inverse ? !res : res;
+      m_eval.reset (prop_id);
+      m_eval.set_shape (&shape);
+
+      bool res = m_expression.execute ().to_bool ();
+      return m_inverse ? !res : res;
+
+    } catch (tl::Exception &ex) {
+      tl::warn << ex.msg ();
+      return false;
+    }
   }
 
   //  only needed for PolygonFilterBase
   virtual bool selected (const db::PolygonRef &shape, db::properties_id_type prop_id) const
   {
-    m_eval.set_prop_id (prop_id);
-    m_eval.set_shape (&shape);
+    try {
 
-    bool res = m_expression.execute ().to_bool ();
-    return m_inverse ? !res : res;
+      m_eval.reset (prop_id);
+      m_eval.set_shape (&shape);
+
+      bool res = m_expression.execute ().to_bool ();
+      return m_inverse ? !res : res;
+
+    } catch (tl::Exception &ex) {
+      tl::warn << ex.msg ();
+      return false;
+    }
   }
 
 public:
diff --git a/src/db/db/gsiDeclDbRegion.cc b/src/db/db/gsiDeclDbRegion.cc
index 496e6fd02..3e72eef94 100644
--- a/src/db/db/gsiDeclDbRegion.cc
+++ b/src/db/db/gsiDeclDbRegion.cc
@@ -320,13 +320,14 @@ Class<property_computation_processor<db::PolygonProcessorBase, db::Region> > dec
   "is attached to the output edge pairs as user properties with the given names.\n"
   "\n"
   "Alternatively, a single expression can be given. In that case, 'put' needs to be used to attach properties "
-  "to the output shape.\n"
+  "to the output shape. You can also use 'skip' to drop shapes in that case.\n"
   "\n"
   "The expression may use the following variables and functions:\n"
   "\n"
   "@ul\n"
   "@li @b shape @/b: The current shape (i.e. 'Polygon' without DBU specified or 'DPolygon' otherwise) @/li\n"
   "@li @b put(<name>, <value>) @/b: Attaches the given value as a property with name 'name' to the output shape @/li\n"
+  "@li @b skip(<flag>) @/b: If called with a 'true' value, the shape is dropped from the output @/li\n"
   "@li @b value(<name>) @/b: The value of the property with the given name (the first one if there are multiple properties with the same name) @/li\n"
   "@li @b values(<name>) @/b: All values of the properties with the given name (returns a list) @/li\n"
   "@li @b <name> @/b: A shortcut for 'value(<name>)' (<name> is used as a symbol) @/li\n"
diff --git a/src/db/db/gsiDeclDbTexts.cc b/src/db/db/gsiDeclDbTexts.cc
index 8cb899b5a..476813cf7 100644
--- a/src/db/db/gsiDeclDbTexts.cc
+++ b/src/db/db/gsiDeclDbTexts.cc
@@ -299,13 +299,14 @@ Class<property_computation_processor<db::TextProcessorBase, db::Texts> > decl_Te
   "is attached to the output edge pairs as user properties with the given names.\n"
   "\n"
   "Alternatively, a single expression can be given. In that case, 'put' needs to be used to attach properties "
-  "to the output shape.\n"
+  "to the output shape. You can also use 'skip' to drop shapes in that case.\n"
   "\n"
   "The expression may use the following variables and functions:\n"
   "\n"
   "@ul\n"
   "@li @b shape @/b: The current shape (i.e. 'Text' without DBU specified or 'DText' otherwise) @/li\n"
   "@li @b put(<name>, <value>) @/b: Attaches the given value as a property with name 'name' to the output shape @/li\n"
+  "@li @b skip(<flag>) @/b: If called with a 'true' value, the shape is dropped from the output @/li\n"
   "@li @b value(<name>) @/b: The value of the property with the given name (the first one if there are multiple properties with the same name) @/li\n"
   "@li @b values(<name>) @/b: All values of the properties with the given name (returns a list) @/li\n"
   "@li @b <name> @/b: A shortcut for 'value(<name>)' (<name> is used as a symbol) @/li\n"
diff --git a/src/drc/drc/built-in-macros/_drc_engine.rb b/src/drc/drc/built-in-macros/_drc_engine.rb
index 600d1b053..40f770d77 100644
--- a/src/drc/drc/built-in-macros/_drc_engine.rb
+++ b/src/drc/drc/built-in-macros/_drc_engine.rb
@@ -453,6 +453,19 @@ module DRC
         DRCPropertyName::new(k)
       end
     end
+
+    def aniso(expression)
+      DRCTransformationVariantHint::new(expression, :is_scale_invariant)
+    end
+
+    def scales(expression)
+      DRCTransformationVariantHint::new(expression, :is_isotropic)
+    end
+
+    def aniso_and_scales(expression)
+      DRCTransformationVariantHint::new(expression, nil)
+    end
+
     
     # %DRC%
     # @brief Specifies "same properties" for operations supporting user properties constraints
diff --git a/src/drc/drc/built-in-macros/_drc_layer.rb b/src/drc/drc/built-in-macros/_drc_layer.rb
index 4f40794b0..acfbba82f 100644
--- a/src/drc/drc/built-in-macros/_drc_layer.rb
+++ b/src/drc/drc/built-in-macros/_drc_layer.rb
@@ -5176,7 +5176,7 @@ CODE
     # %DRC%
     # @name evaluate
     # @brief Evaluate expressions on the shapes of the layer
-    # @synopsis layer.evaluate(expression [, variables])
+    # @synopsis layer.evaluate(expression [, variables [, keep_properties ]])
     #
     # Evaluates the given expression on the shapes of the layer.
     # The expression needs to be written in the KLayout expressions
@@ -5185,12 +5185,14 @@ CODE
     # The expressions can place properties on the shapes using the 
     # "put" function. As input, the expressions will receive the
     # (merged) shapes in micrometer units (e.g. RBA::DPolygon type) 
-    # by calling the "shape" function.
+    # by calling the "shape" function. You can also call 'skip' with
+    # a 'true' value to drop the shape from the output entirely.
     #
     # Available functions are:
     # 
     # @ul
-    # @li "put(name, value)": creates a property with name 'name' and 'value' value @/li
+    # @li "put(name, value)": creates a property with the given name and value @/li
+    # @li "skip(flag)": if called with a 'true' value, the shape will be dropped from the output @/li
     # @li "shape": the current shape in micrometer units @/li
     # @li "value(name)": the value of a property with name 'name' or nil if the current shape does not have a property with this name @/li
     # @ul
@@ -5202,50 +5204,106 @@ CODE
     # becomes available as variables in the expression. This eliminates the need
     # to build expression strings to pass variable values.
     #
-    # The following example computes the area of the shapes and puts them
-    # into a property 'AREA':
+    # If 'keep_properties' is true, the existing properties of the shape will be kept.
+    # Otherwise (the default), existing properties will be removed before adding new
+    # ones with 'put'.
+    #
+    # The expressions require a hint
+    # whether the they make use of anisotropic or scale-dependent properties.
+    # For example, the height of a box is an anisotropic property. If a check is made
+    # inside a rotated cell, the height transforms to a width and the check renders 
+    # different results for the same cell if the cell is placed rotated and non-rotated.
+    # The solution is cell variant formation.
+    # 
+    # Similarly, if a check is made against physical dimensions, the check will have
+    # different results for cells placed with different magnifications. Such a check
+    # is not scale-invariant.
+    #
+    # By default it is assumed that the expressions are isotropic and scale invariant.
+    # You can mark an expression as anisotropic and/or scale dependent using the following
+    # expression modifiers:
     #
     # @code
-    # layer.evalute("put('AREA', shape.area)")
+    # # isotropic and scale invariant
+    # layer.evaluate("put('holes', shape.holes)")
+    #
+    # # anisotropic, but scale invariant
+    # layer.evaluate(aniso("put('aspect_ratio', shape.bbox.height/shape.bbox.width)"))
+    #
+    # # isotropic, but not scale invariant
+    # layer.evaluate(scales("put('area', shape.area)"))
+    #
+    # # anisotropic and not scale invariant
+    # layer.evaluate(aniso_and_scales("put('width', shape.bbox.width)"))
     # @/code
     #
+    # If you forget to specify this hint, the expression will use the local 
+    # shape properties and fail to correctly produce the results in the presence
+    # of deep mode and rotated or magnified cell instances.
+    #
+    # The following example computes the area of the shapes and puts them
+    # into a property 'area':
+    #
+    # @code
+    # layer.evaluate(scales("put('area', shape.area)"))
+    # @/code
+    #
+    # NOTE: GDS does not support properties with string names, so 
+    # either save to OASIS or use integer numbers for the property names.
+    #
     # This version modifies the input layer. A version that returns
     # a new layer is \evaluated.
     
     # %DRC%
     # @name evaluated
     # @brief Evaluate expressions on the shapes of the layer and returns a new layer
-    # @synopsis layer.evaluated(expression [, variables])
+    # @synopsis layer.evaluated(expression [, variables [, keep_properties]])
     # 
     # This method is the out-of-place version of \evaluate.
 
-    def _make_proc(expression, variables)
+    def _make_proc(expression, variables, keep_properties)
 
-      expression.is_a?(String) || raise("'expression' must be a string")
+      if expression.is_a?(String)
+        expression = DRCTransformationVariantHint::new(expression)
+      elsif expression.is_a?(DRCTransformationVariantHint)
+        expression.expression.is_a?(String) || raise("'expression' must be a string")
+      else
+        raise("'expression' must be a string or a string decorated with a transformation variant hint")
+      end
       variables.is_a?(Hash) || raise("'variables' must be a hash")
 
       if data.is_a?(RBA::Region)
-        RBA::PolygonPropertiesExpressions::new(data, expression, dbu: @engine.dbu, variables: variables)
+        pr = RBA::PolygonPropertiesExpressions::new(data, expression.expression, copy_properties: keep_properties, dbu: @engine.dbu, variables: variables)
       elsif data.is_a?(RBA::Edges)
-        RBA::EdgePropertiesExpressions::new(data, expression, dbu: @engine.dbu, variables: variables)
+        pr = RBA::EdgePropertiesExpressions::new(data, expression.expression, copy_properties: keep_properties, dbu: @engine.dbu, variables: variables)
       elsif data.is_a?(RBA::EdgePairs)
-        RBA::EdgePairPropertiesExpressions::new(data, expression, dbu: @engine.dbu, variables: variables)
+        pr = RBA::EdgePairPropertiesExpressions::new(data, expression.expression, copy_properties: keep_properties, dbu: @engine.dbu, variables: variables)
       elsif data.is_a?(RBA::Texts)
-        RBA::TextPropertiesExpressions::new(data, expression, dbu: @engine.dbu, variables: variables)
+        pr = RBA::TextPropertiesExpressions::new(data, expression.expression, copy_properties: keep_properties, dbu: @engine.dbu, variables: variables)
       else
-        nil
+        pr = nil
       end
 
+      pr && expression.apply(pr)
+      pr
+
     end
 
-    def evaluate(expression, variables = {})
+    def evaluate(expression, variables = {}, keep_properties = false)
       @engine._context("evaluate") do
-        pr = _make_proc(expression, variables)
+        pr = _make_proc(expression, variables, keep_properties)
         @engine._tcmd(self.data, 0, self.data.class, :process, pr)
         self
       end
     end
     
+    def evaluated(expression, variables = {}, keep_properties = false)
+      @engine._context("evaluated") do
+        pr = _make_proc(expression, variables, keep_properties)
+        DRCLayer::new(@engine, @engine._tcmd(self.data, 0, self.data.class, :processed, pr))
+      end
+    end
+    
     # %DRC%
     # @name select_if
     # @brief Selects shapes of a layer based on the evaluation of an expression
@@ -5255,6 +5313,8 @@ CODE
     # If the evaluation gives a 'true' value, the shape is selected. Otherwise
     # it is discarded.
     #
+    # The expression is written in KLayout expression notation. 
+    #
     # As input, the expressions will receive the
     # (merged) shapes in micrometer units (e.g. RBA::DPolygon type) 
     # by calling the "shape" function.
@@ -5269,6 +5329,39 @@ CODE
     # Properties with well-formed names (e.g. "VALUE") are available as
     # variables in the expressions as a shortcut.
     #
+    # The expressions require a hint
+    # whether the they make use of anisotropic or scale-dependent properties.
+    # For example, the height of a box is an anisotropic property. If a check is made
+    # inside a rotated cell, the height transforms to a width and the check renders 
+    # different results for the same cell if the cell is placed rotated and non-rotated.
+    # The solution is cell variant formation.
+    # 
+    # Similarly, if a check is made against physical dimensions, the check will have
+    # different results for cells placed with different magnifications. Such a check
+    # is not scale-invariant.
+    #
+    # By default it is assumed that the expressions are isotropic and scale invariant.
+    # You can mark an expression as anisotropic and/or scale dependent using the following
+    # expression modifiers:
+    #
+    # @code
+    # # isotropic and scale invariant
+    # layer.select_if("shape.holes > 0")
+    #
+    # # anisotropic, but scale invariant
+    # layer.select_if(aniso("shape.bbox.height/shape.bbox.width > 2"))
+    #
+    # # isotropic, but not scale invariant
+    # layer.select_if(scales("shape.area > 10.0"))
+    #
+    # # anisotropic and not scale invariant
+    # layer.select_if(aniso_and_scales("shape.bbox.width > 10.0"))
+    # @/code
+    #
+    # If you forget to specify this hint, the expression will use the local 
+    # shape properties and fail to correctly produce the results in the presence
+    # of deep mode and rotated or magnified cell instances.
+    #
     # 'variables' can be a hash of arbitrary names and values. Each of these values
     # becomes available as variables in the expression. This eliminates the need
     # to build expression strings to pass variable values.
@@ -5277,7 +5370,7 @@ CODE
     # less than 10 square micrometers:
     #
     # @code
-    # layer.select("shape.area < 10.0")
+    # layer.select(scales("shape.area < 10.0"))
     # @/code
     #
     # This version modifies the input layer. A version that returns
@@ -5302,30 +5395,39 @@ CODE
     # less than 10 square micrometers and one with the shapes with a bigger area:
     #
     # @code
-    # (smaller, bigger) = layer.split_if("shape.area < 10.0")
+    # (smaller, bigger) = layer.split_if(scales("shape.area < 10.0"))
     # @/code
 
     def _make_filter(expression, variables)
 
-      expression.is_a?(String) || raise("'expression' must be a string")
+      if expression.is_a?(String)
+        expression = DRCTransformationVariantHint::new(expression)
+      elsif expression.is_a?(DRCTransformationVariantHint)
+        expression.expression.is_a?(String) || raise("'expression' must be a string")
+      else
+        raise("'expression' must be a string or a string decorated with a transformation variant hint")
+      end
       variables.is_a?(Hash) || raise("'variables' must be a hash")
 
       if data.is_a?(RBA::Region)
-        RBA::PolygonFilterBase::expression_filter(expression, variables: variables)
+        f = RBA::PolygonFilterBase::expression_filter(expression.expression, dbu: @engine.dbu, variables: variables)
       elsif data.is_a?(RBA::Edges)
-        RBA::EdgeFilterBase::expression_filter(expression, variables: variables)
+        f = RBA::EdgeFilterBase::expression_filter(expression.expression, dbu: @engine.dbu, variables: variables)
       elsif data.is_a?(RBA::EdgePairs)
-        RBA::EdgeFilterBase::expression_filter(expression, variables: variables)
+        f = RBA::EdgeFilterBase::expression_filter(expression.expression, dbu: @engine.dbu, variables: variables)
       elsif data.is_a?(RBA::Texts)
-        RBA::TextFilterBase::expression_filter(expression, variables: variables)
+        f = RBA::TextFilterBase::expression_filter(expression.expression, dbu: @engine.dbu, variables: variables)
       else
-        nil
+        f = nil
       end
 
+      f && expression.apply(f)
+      f
+
     end
 
     def select_if(expression, variables = {})
-      @engine._context("evaluate") do
+      @engine._context("select_if") do
         f = _make_filter(expression, variables)
         @engine._tcmd(self.data, 0, self.data.class, :filter, f)
         self
@@ -5333,16 +5435,17 @@ CODE
     end
     
     def selected_if(expression, variables = {})
-      @engine._context("evaluated") do
+      @engine._context("selected_if") do
         f = _make_filter(expression, variables)
         DRCLayer::new(@engine, @engine._tcmd(self.data, 0, self.data.class, :filtered, f))
       end
     end
     
     def split_if(expression, variables = {})
-      @engine._context("evaluated") do
+      @engine._context("split_if") do
         f = _make_filter(expression, variables)
-        DRCLayer::new(@engine, @engine._tcmd(self.data, 0, self.data.class, :split_filter, f))
+        res = @engine._tcmd(self.data, 0, self.data.class, :split_filter, f)
+        [ DRCLayer::new(@engine, res[0]), DRCLayer::new(@engine, res[1]) ]
       end
     end
     
diff --git a/src/drc/drc/built-in-macros/_drc_netter.rb b/src/drc/drc/built-in-macros/_drc_netter.rb
index 554723391..8c009b57c 100644
--- a/src/drc/drc/built-in-macros/_drc_netter.rb
+++ b/src/drc/drc/built-in-macros/_drc_netter.rb
@@ -833,6 +833,9 @@ module DRC
     #
     # antenna_errors = evaluate_nets(gate, { "MET" => metal }, expression, variables)
     # @/code
+    #
+    # NOTE: GDS does not support properties with string names, so 
+    # either save to OASIS or use integer numbers for the property names.
 
     def evaluate_nets(primary, secondary, expression, variables = {})
 
diff --git a/src/drc/drc/built-in-macros/_drc_tags.rb b/src/drc/drc/built-in-macros/_drc_tags.rb
index 710626f53..923ff803e 100644
--- a/src/drc/drc/built-in-macros/_drc_tags.rb
+++ b/src/drc/drc/built-in-macros/_drc_tags.rb
@@ -575,5 +575,20 @@ module DRC
     end
   end
 
+  class DRCTransformationVariantHint
+    def initialize(expression, mode = :is_isotropic_and_scale_invariant)
+      @expression = expression
+      @mode = mode
+    end
+    def expression
+      @expression
+    end
+    def apply(pr)
+      if @mode
+        pr.send(@mode)
+      end
+    end
+  end
+
 end
 
diff --git a/src/drc/unit_tests/drcSimpleTests.cc b/src/drc/unit_tests/drcSimpleTests.cc
index 0f698a1ff..cd25b1774 100644
--- a/src/drc/unit_tests/drcSimpleTests.cc
+++ b/src/drc/unit_tests/drcSimpleTests.cc
@@ -2024,3 +2024,13 @@ TEST(142d_evaluate_nets)
   run_test (_this, "142", true);
 }
 
+TEST(143_evaluate_and_filter)
+{
+  run_test (_this, "143", false);
+}
+
+TEST(143d_evaluate_and_filter)
+{
+  run_test (_this, "143", true);
+}
+
diff --git a/testdata/drc/drcSimpleTests_143.drc b/testdata/drc/drcSimpleTests_143.drc
new file mode 100644
index 000000000..df9a4f129
--- /dev/null
+++ b/testdata/drc/drcSimpleTests_143.drc
@@ -0,0 +1,51 @@
+
+source $drc_test_source
+target $drc_test_target
+
+if $drc_test_deep
+  deep
+end
+
+l1 = input(1, 0, enable_props)
+l2 = input(2, 0, enable_props)
+
+l1.output(1, 0)
+l2.output(2, 0)
+
+l2.evaluated("put(2, to_f(value(17))*2.0)").output(10, 0)
+l2.evaluated("put(2, to_f(value(17))*factor)", { "factor" => 3.0 }, true).output(11, 0)
+l1.evaluated(aniso("put(2, shape.bbox.height/shape.bbox.width)")).output(12, 0)
+l1.evaluated(scales("put(2, shape.area)")).output(13, 0)
+l1.evaluated(aniso_and_scales("put(2, shape.bbox.width)")).output(14, 0)
+
+d = l2.dup
+d.evaluate("put(2, to_f(value(17))*2.0)").output(20, 0)
+d = l2.dup
+d.evaluate("put(2, to_f(value(17))*factor)", { "factor" => 3.0 }, true).output(21, 0)
+d = l1.dup
+d.evaluate(aniso("put(2, shape.bbox.height/shape.bbox.width)")).output(22, 0)
+d = l1.dup
+d.evaluate(scales("put(2, shape.area)")).output(23, 0)
+d = l1.dup
+d.evaluate(aniso_and_scales("put(2, shape.bbox.width)")).output(24, 0)
+
+l2.selected_if("to_f(value(17))<3.0").output(30, 0)
+l2.selected_if("to_f(value(17))<thr)", { "thr" => 3.0 }).output(31, 0)
+l1.selected_if(aniso("shape.bbox.height/shape.bbox.width<1.0")).output(32, 0)
+l1.selected_if(scales("shape.area<20.0")).output(33, 0)
+l1.selected_if(aniso_and_scales("shape.bbox.width<=5")).output(34, 0)
+
+d = l2.dup
+d.select_if("to_f(value(17))<3.0").output(40, 0)
+d = l2.dup
+d.select_if("to_f(value(17))<thr)", { "thr" => 3.0 }).output(41, 0)
+d = l1.dup
+d.select_if(aniso("shape.bbox.height/shape.bbox.width<1.0")).output(42, 0)
+d = l1.dup
+d.select_if(scales("shape.area<20.0")).output(43, 0)
+d = l1.dup
+d.select_if(aniso_and_scales("shape.bbox.width<=5")).output(44, 0)
+
+l2.split_if("to_f(value(17))<3.0")[0].output(50, 0)
+l2.split_if("to_f(value(17))<3.0")[1].output(51, 0)
+
diff --git a/testdata/drc/drcSimpleTests_143.gds b/testdata/drc/drcSimpleTests_143.gds
new file mode 100644
index 000000000..6f18d6afb
Binary files /dev/null and b/testdata/drc/drcSimpleTests_143.gds differ
diff --git a/testdata/drc/drcSimpleTests_au143.gds b/testdata/drc/drcSimpleTests_au143.gds
new file mode 100644
index 000000000..7159c09c4
Binary files /dev/null and b/testdata/drc/drcSimpleTests_au143.gds differ
diff --git a/testdata/drc/drcSimpleTests_au143d.gds b/testdata/drc/drcSimpleTests_au143d.gds
new file mode 100644
index 000000000..d8a824d25
Binary files /dev/null and b/testdata/drc/drcSimpleTests_au143d.gds differ