diff --git a/src/drc/drc/built-in-macros/_drc_complex_ops.rb b/src/drc/drc/built-in-macros/_drc_complex_ops.rb
index 8569143f0..adf7b579f 100644
--- a/src/drc/drc/built-in-macros/_drc_complex_ops.rb
+++ b/src/drc/drc/built-in-macros/_drc_complex_ops.rb
@@ -1119,7 +1119,7 @@ class DRCOpNodeWithCompare < DRCOpNode
   end
   
   def _self_or_original
-    return self.original || self
+    return (self.original || self).dup
   end
   
   def ==(other)
@@ -1505,7 +1505,6 @@ class DRCOpNodeCheck < DRCOpNodeWithCompare
     if self.gt || self.ge
       dmax = self.ge ? @engine._make_value(self.ge) : @engine._make_value(self.gt) + 1
       max_check = RBA::CompoundRegionOperationNode::send(factory, dmax, *self.args + [ true ])
-      res_max = RBA::CompoundRegionOperationNode::new_edge_pair_to_first_edges(max_check)
       if res
         if self.check == :width || self.check == :notch
           # Same polygon check - we need to take both edges of the result
@@ -1513,9 +1512,10 @@ class DRCOpNodeCheck < DRCOpNodeWithCompare
         else
           and_with = RBA::CompoundRegionOperationNode::new_edge_pair_to_first_edges(res)
         end
+        res_max = RBA::CompoundRegionOperationNode::new_edge_pair_to_first_edges(max_check)
         res = RBA::CompoundRegionOperationNode::new_geometrical_boolean(RBA::CompoundRegionOperationNode::GeometricalOp::And, and_with, res_max)
       else
-        res = res_max
+        res = max_check
       end
     end
     
diff --git a/src/drc/drc/built-in-macros/_drc_cop_integration.rb b/src/drc/drc/built-in-macros/_drc_cop_integration.rb
index 2a76fa4df..f9f233857 100644
--- a/src/drc/drc/built-in-macros/_drc_cop_integration.rb
+++ b/src/drc/drc/built-in-macros/_drc_cop_integration.rb
@@ -76,8 +76,8 @@ module DRC
     def drc(op)
       @engine._context("drc") do
         requires_region
-        expr.is_a?(DRCOpNode) || raise("A DRC expression is required for the argument (got #{expr.inspect})")
-        return DRCLayer::new(@engine, self.data.complex_op(op.create_node({})))
+        op.is_a?(DRCOpNode) || raise("A DRC expression is required for the argument (got #{op.inspect})")
+        DRCLayer::new(@engine, self.data.complex_op(op.create_node({})))
       end
     end
     
@@ -632,9 +632,13 @@ CODE
     # out = in.drc(0.1.um <= enclosing(other) < 0.2.um)
     # @/code
     #
-    # The result of the enclosing check are edge pairs forming the violation
-    # markers. With a lower limit, these markers are formed by two, identical but opposite edges attached to 
-    # the primary shape. Without a lower limit, the first edge of the marker is attached to the 
+    # The result of the enclosing check are edges or edge pairs forming the markers.
+    # These markers indicate the presence of the specified condition.
+    # 
+    # With a lower and upper limit, the results are edges marking the positions on the 
+    # primary shape where the condition is met.
+    # With a lower limit alone, these markers are formed by two, identical but opposite edges attached to 
+    # the primary shape. Without an upper limit only, the first edge of the marker is attached to the 
     # primary shape while the second edge is attached to the shape of the "other" layer.
     
     # %DRC%
@@ -682,9 +686,10 @@ CODE
     # out = in.drc(0.1.um <= width < 0.2.um)
     # @/code
     #
-    # The result of the width check are edge pairs forming the violation
-    # markers. With a lower limit, these markers are formed by two, identical but opposite edges attached to 
-    # the primary shape. Without a lower limit, both edges are attached to different sides of the primary 
+    # With a lower and upper limit, the results are edges marking the positions on the 
+    # primary shape where the condition is met.
+    # With a lower limit alone, these markers are formed by two, identical but opposite edges attached to 
+    # the primary shape. Without an upper limit only, both edges are attached to different sides of the primary
     # shape.
     
     # %DRC%
diff --git a/src/drc/unit_tests/drcGenericTests.cc b/src/drc/unit_tests/drcGenericTests.cc
new file mode 100644
index 000000000..41b416b4e
--- /dev/null
+++ b/src/drc/unit_tests/drcGenericTests.cc
@@ -0,0 +1,80 @@
+
+/*
+
+  KLayout Layout Viewer
+  Copyright (C) 2006-2021 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 "tlUnitTest.h"
+#include "dbReader.h"
+#include "dbTestSupport.h"
+#include "dbNetlist.h"
+#include "dbNetlistSpiceReader.h"
+#include "lymMacro.h"
+#include "tlFileUtils.h"
+
+static void runTest (tl::TestBase *_this, const std::string &number, bool deep)
+{
+  std::string rs = tl::testsrc ();
+  rs += "/testdata/drc/drcGenericTests_" + number + ".drc";
+
+  std::string input = tl::testsrc ();
+  input += "/testdata/drc/drcGenericTests_" + number + ".gds";
+
+  std::string au = tl::testsrc ();
+  au += "/testdata/drc/drcGenericTests_au" + number + std::string (deep ? "d" : "") + ".gds";
+
+  std::string output = _this->tmp_file ("tmp.gds");
+
+  {
+    //  Set some variables
+    lym::Macro config;
+    config.set_text (tl::sprintf (
+        "$drc_test_source = '%s'\n"
+        "$drc_test_target = '%s'\n"
+        "$drc_test_deep = %s\n"
+      , input, output, deep ? "true" : "false")
+    );
+    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);
+}
+
+TEST(1)
+{
+  runTest (_this, "1", false);
+}
+
+TEST(1d)
+{
+  runTest (_this, "1", true);
+}
diff --git a/src/drc/unit_tests/unit_tests.pro b/src/drc/unit_tests/unit_tests.pro
index 1acc6688f..30b2d3db0 100644
--- a/src/drc/unit_tests/unit_tests.pro
+++ b/src/drc/unit_tests/unit_tests.pro
@@ -8,6 +8,7 @@ include($$PWD/../../lib_ut.pri)
 
 SOURCES = \
   drcBasicTests.cc \
+  drcGenericTests.cc \
   drcSimpleTests.cc \
   drcSuiteTests.cc \
 
diff --git a/testdata/drc/drcGenericTests_1.drc b/testdata/drc/drcGenericTests_1.drc
new file mode 100644
index 000000000..3bbb96f4b
--- /dev/null
+++ b/testdata/drc/drcGenericTests_1.drc
@@ -0,0 +1,30 @@
+
+source $drc_test_source
+target $drc_test_target
+
+if $drc_test_deep
+  deep
+end
+
+l1 = input(1, 0)
+l2 = input(2, 0)
+l3 = input(3, 0)
+
+l1.output(1, 0)
+l2.output(2, 0)
+l3.output(3, 0)
+
+wcheck = width(projection)
+
+l1.drc(wcheck < 1.0).polygons.output(100, 0)
+l1.drc(wcheck <= 0.5).polygons.output(101, 0)
+l1.drc(1.0 > wcheck).polygons.output(102, 0)
+l1.drc(0.5 >= wcheck).polygons.output(103, 0)
+l1.drc(wcheck > 1.0).output(104, 0)
+l1.drc(wcheck >= 1.5).output(105, 0)
+l1.drc(1.0 < wcheck).output(106, 0)
+l1.drc(1.5 <= wcheck).output(107, 0)
+l1.drc(wcheck == 1.5).output(108, 0)
+l1.drc(1.0 <= wcheck <= 1.5).output(109, 0)
+l1.drc(1.0 < wcheck < 2.0).output(110, 0)
+
diff --git a/testdata/drc/drcGenericTests_1.gds b/testdata/drc/drcGenericTests_1.gds
new file mode 100644
index 000000000..18c6261a1
Binary files /dev/null and b/testdata/drc/drcGenericTests_1.gds differ
diff --git a/testdata/drc/drcGenericTests_au1.gds b/testdata/drc/drcGenericTests_au1.gds
new file mode 100644
index 000000000..8b1e44020
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diff --git a/testdata/drc/drcGenericTests_au1d.gds b/testdata/drc/drcGenericTests_au1d.gds
new file mode 100644
index 000000000..3e467d9dd
Binary files /dev/null and b/testdata/drc/drcGenericTests_au1d.gds differ