diff --git a/src/db/db/dbNetlistSpiceWriter.cc b/src/db/db/dbNetlistSpiceWriter.cc
index 5bf03d678..b5893bee3 100644
--- a/src/db/db/dbNetlistSpiceWriter.cc
+++ b/src/db/db/dbNetlistSpiceWriter.cc
@@ -117,6 +117,7 @@ void NetlistSpiceWriterDelegate::write_device (const db::Device &dev) const
       os << " ";
       os << format_name (dev.device_class ()->name ());
     }
+    os << format_params (dev, db::DeviceClassCapacitor::param_id_C);
 
   } else if (ind) {
 
@@ -129,6 +130,7 @@ void NetlistSpiceWriterDelegate::write_device (const db::Device &dev) const
       os << " ";
       os << format_name (dev.device_class ()->name ());
     }
+    os << format_params (dev, db::DeviceClassInductor::param_id_L);
 
   } else if (res || res3) {
 
@@ -141,6 +143,7 @@ void NetlistSpiceWriterDelegate::write_device (const db::Device &dev) const
       os << " ";
       os << format_name (dev.device_class ()->name ());
     }
+    os << format_params (dev, db::DeviceClassResistor::param_id_R);
 
   } else if (diode) {
 
diff --git a/src/db/db/gsiDeclDbNetlist.cc b/src/db/db/gsiDeclDbNetlist.cc
index cfdc5a341..0941d63c3 100644
--- a/src/db/db/gsiDeclDbNetlist.cc
+++ b/src/db/db/gsiDeclDbNetlist.cc
@@ -251,6 +251,24 @@ static void add_other_abstracts (db::Device *device, const db::DeviceAbstractRef
   device->other_abstracts ().push_back (ref);
 }
 
+static const db::Net *net_for_terminal_by_name_const (const db::Device *device, const std::string &name)
+{
+  if (! device->device_class () || ! device->device_class ()->has_terminal_with_name (name)) {
+    return 0;
+  } else {
+    return device->net_for_terminal (device->device_class ()->terminal_id_for_name (name));
+  }
+}
+
+static const db::Net *net_for_terminal_by_name (db::Device *device, const std::string &name)
+{
+  if (! device->device_class () || ! device->device_class ()->has_terminal_with_name (name)) {
+    return 0;
+  } else {
+    return device->net_for_terminal (device->device_class ()->terminal_id_for_name (name));
+  }
+}
+
 Class<db::Device> decl_dbDevice (decl_dbNetlistObject, "db", "Device",
   gsi::method ("device_class", &db::Device::device_class,
     "@brief Gets the device class the device belongs to.\n"
@@ -337,6 +355,18 @@ Class<db::Device> decl_dbDevice (decl_dbNetlistObject, "db", "Device",
     "\n\n"
     "This constness variant has been introduced in version 0.26.8"
   ) +
+  gsi::method_ext ("net_for_terminal", net_for_terminal_by_name_const, gsi::arg ("terminal_name"),
+    "@brief Gets the net connected to the specified terminal.\n"
+    "If the terminal is not connected, nil is returned for the net."
+    "\n\n"
+    "This convenience method has been introduced in version 0.27.3.\n"
+  ) +
+  gsi::method_ext ("net_for_terminal", net_for_terminal_by_name, gsi::arg ("terminal_name"),
+    "@brief Gets the net connected to the specified terminal (non-const version).\n"
+    "If the terminal is not connected, nil is returned for the net."
+    "\n\n"
+    "This convenience method has been introduced in version 0.27.3.\n"
+  ) +
   gsi::method ("connect_terminal", &db::Device::connect_terminal, gsi::arg ("terminal_id"), gsi::arg ("net"),
     "@brief Connects the given terminal to the specified net.\n"
   ) +
diff --git a/src/drc/drc/built-in-macros/_drc_engine.rb b/src/drc/drc/built-in-macros/_drc_engine.rb
index 51f44c266..6359bff21 100644
--- a/src/drc/drc/built-in-macros/_drc_engine.rb
+++ b/src/drc/drc/built-in-macros/_drc_engine.rb
@@ -4,6 +4,15 @@ require 'pathname'
 
 module DRC
 
+  class CustomDeviceClassFactory < RBA::DeviceClassFactory
+    def initialize(cls)
+      @cls = cls
+    end
+    def create_class
+      @cls.new
+    end
+  end
+
   # The DRC engine
   
   # %DRC%
@@ -308,22 +317,57 @@ module DRC
     # @brief Defines SPICE output format (with options) 
     # @name write_spice
     # @synopsis write_spice([ use_net_names [, with_comments ] ])
+    # @synopsis write_spice(writer_delegate [, use_net_names [, with_comments ] ])
     # Use this option in \target_netlist for the format parameter to 
     # specify SPICE format.
     # "use_net_names" and "with_comments" are boolean parameters indicating
     # whether to use named nets (numbers if false) and whether to add 
     # information comments such as instance coordinates or pin names.
+    #
+    # "writer_delegate" allows using a \NetlistSpiceWriterDelegate object to 
+    # control the actual writing.
+
+    def write_spice(*args)
 
-    def write_spice(use_net_names = nil, with_comments = nil)
       self._context("write_spice") do
-        writer = RBA::NetlistSpiceWriter::new
+
+        delegate = nil
+        use_net_names = nil
+        with_comments = nil
+        args.each do |a|
+          if (a == false || a == true) && (use_net_names == nil || with_comments == nil)
+            if use_net_names == nil
+              use_net_names = a
+            else
+              with_comments = a
+            end
+          elsif a.is_a?(RBA::NetlistSpiceWriterDelegate)
+            delegate = a
+          else
+            raise("Too many arguments specified or argument is of wrong type: " + a.inspect)
+          end
+        end
+            
+        writer = RBA::NetlistSpiceWriter::new(delegate)
         if use_net_names != nil
           writer.use_net_names = use_net_names
         end
         if with_comments != nil
           writer.with_comments = with_comments
         end
+
         writer
+
+      end
+    end
+
+    def _make_factory(cls)
+      if !cls
+        return nil
+      elsif !cls.is_a?(Class)
+        raise("Expected a class object for the 'class' argument of device extractors")
+      else
+        CustomDeviceClassFactory::new(cls)
       end
     end
 
@@ -331,15 +375,16 @@ module DRC
     # @brief Supplies the MOS3 transistor extractor class
     # @name mos3
     # @synopsis mos3(name)
+    # @synopsis mos3(name, class)
     # Use this class with \extract_devices to specify extraction of a 
     # three-terminal MOS transistor.
     #
     # See RBA::DeviceExtractorMOS3Transistor for more details
     # about this extractor (non-strict mode applies for 'mos3').
 
-    def mos3(name)
+    def mos3(name, cls = nil)
       self._context("mos3") do
-        RBA::DeviceExtractorMOS3Transistor::new(name)
+        RBA::DeviceExtractorMOS3Transistor::new(name, false, _make_factory(cls))
       end
     end
 
@@ -347,15 +392,16 @@ module DRC
     # @brief Supplies the MOS4 transistor extractor class
     # @name mos4
     # @synopsis mos4(name)
+    # @synopsis mos4(name, class)
     # Use this class with \extract_devices to specify extraction of a 
     # four-terminal MOS transistor.
     #
     # See RBA::DeviceExtractorMOS4Transistor for more details
     # about this extractor (non-strict mode applies for 'mos4').
 
-    def mos4(name)
+    def mos4(name, cls = nil)
       self._context("mos4") do
-        RBA::DeviceExtractorMOS4Transistor::new(name)
+        RBA::DeviceExtractorMOS4Transistor::new(name, false, _make_factory(cls))
       end
     end
 
@@ -363,6 +409,7 @@ module DRC
     # @brief Supplies the DMOS3 transistor extractor class
     # @name dmos3
     # @synopsis dmos3(name)
+    # @synopsis dmos3(name, class)
     # Use this class with \extract_devices to specify extraction of a 
     # three-terminal DMOS transistor. A DMOS transistor is essentially
     # the same than a MOS transistor, but source and drain are 
@@ -371,9 +418,9 @@ module DRC
     # See RBA::DeviceExtractorMOS3Transistor for more details
     # about this extractor (strict mode applies for 'dmos3').
 
-    def dmos3(name)
+    def dmos3(name, cls = nil)
       self._context("dmos3") do
-        RBA::DeviceExtractorMOS3Transistor::new(name, true)
+        RBA::DeviceExtractorMOS3Transistor::new(name, true, _make_factory(cls))
       end
     end
 
@@ -381,6 +428,7 @@ module DRC
     # @brief Supplies the MOS4 transistor extractor class
     # @name dmos4
     # @synopsis dmos4(name)
+    # @synopsis dmos4(name, class)
     # Use this class with \extract_devices to specify extraction of a 
     # four-terminal DMOS transistor. A DMOS transistor is essentially
     # the same than a MOS transistor, but source and drain are 
@@ -389,9 +437,9 @@ module DRC
     # See RBA::DeviceExtractorMOS4Transistor for more details
     # about this extractor (strict mode applies for 'dmos4').
 
-    def dmos4(name)
+    def dmos4(name, cls = nil)
       self._context("dmos4") do
-        RBA::DeviceExtractorMOS4Transistor::new(name, true)
+        RBA::DeviceExtractorMOS4Transistor::new(name, true, _make_factory(cls))
       end
     end
 
@@ -399,15 +447,16 @@ module DRC
     # @brief Supplies the BJT3 transistor extractor class
     # @name bjt3
     # @synopsis bjt3(name)
+    # @synopsis bjt3(name, class)
     # Use this class with \extract_devices to specify extraction of a 
     # bipolar junction transistor
     #
     # See RBA::DeviceExtractorBJT3Transistor for more details
     # about this extractor.
 
-    def bjt3(name)
+    def bjt3(name, cls = nil)
       self._context("bjt3") do
-        RBA::DeviceExtractorBJT3Transistor::new(name)
+        RBA::DeviceExtractorBJT3Transistor::new(name, _make_factory(cls))
       end
     end
 
@@ -415,15 +464,16 @@ module DRC
     # @brief Supplies the BJT4 transistor extractor class
     # @name bjt4
     # @synopsis bjt4(name)
+    # @synopsis bjt4(name, class)
     # Use this class with \extract_devices to specify extraction of a 
     # bipolar junction transistor with a substrate terminal
     #
     # See RBA::DeviceExtractorBJT4Transistor for more details
     # about this extractor.
 
-    def bjt4(name)
+    def bjt4(name, cls = nil)
       self._context("bjt4") do
-        RBA::DeviceExtractorBJT4Transistor::new(name)
+        RBA::DeviceExtractorBJT4Transistor::new(name, _make_factory(cls))
       end
     end
 
@@ -431,15 +481,16 @@ module DRC
     # @brief Supplies the diode extractor class
     # @name diode
     # @synopsis diode(name)
+    # @synopsis diode(name, class)
     # Use this class with \extract_devices to specify extraction of a 
     # planar diode 
     #
     # See RBA::DeviceExtractorDiode for more details
     # about this extractor.
 
-    def diode(name)
+    def diode(name, cls = nil)
       self._context("diode") do
-        RBA::DeviceExtractorDiode::new(name)
+        RBA::DeviceExtractorDiode::new(name, _make_factory(cls))
       end
     end
 
@@ -447,6 +498,7 @@ module DRC
     # @brief Supplies the resistor extractor class
     # @name resistor
     # @synopsis resistor(name, sheet_rho)
+    # @synopsis resistor(name, sheet_rho, class)
     # Use this class with \extract_devices to specify extraction of a resistor.
     #
     # The sheet_rho value is the sheet resistance in ohms/square. It is used
@@ -455,9 +507,9 @@ module DRC
     # See RBA::DeviceExtractorResistor for more details
     # about this extractor.
 
-    def resistor(name, sheet_rho)
+    def resistor(name, sheet_rho, cls = nil)
       self._context("resistor") do
-        RBA::DeviceExtractorResistor::new(name, sheet_rho)
+        RBA::DeviceExtractorResistor::new(name, sheet_rho, _make_factory(cls))
       end
     end
 
@@ -465,6 +517,7 @@ module DRC
     # @brief Supplies the resistor extractor class that includes a bulk terminal
     # @name resistor_with_bulk
     # @synopsis resistor_with_bulk(name, sheet_rho)
+    # @synopsis resistor_with_bulk(name, sheet_rho, class)
     # Use this class with \extract_devices to specify extraction of a resistor 
     # with a bulk terminal.
     # The sheet_rho value is the sheet resistance in ohms/square.
@@ -472,9 +525,9 @@ module DRC
     # See RBA::DeviceExtractorResistorWithBulk for more details
     # about this extractor.
 
-    def resistor_with_bulk(name, sheet_rho)
+    def resistor_with_bulk(name, sheet_rho, cls = nil)
       self._context("resistor_with_bulk") do
-        RBA::DeviceExtractorResistorWithBulk::new(name, sheet_rho)
+        RBA::DeviceExtractorResistorWithBulk::new(name, sheet_rho, _make_factory(cls))
       end
     end
 
@@ -482,15 +535,16 @@ module DRC
     # @brief Supplies the capacitor extractor class
     # @name capacitor
     # @synopsis capacitor(name, area_cap)
+    # @synopsis capacitor(name, area_cap, class)
     # Use this class with \extract_devices to specify extraction of a capacitor.
     # The area_cap argument is the capacitance in Farad per square micrometer.
     #
     # See RBA::DeviceExtractorCapacitor for more details
     # about this extractor.
 
-    def capacitor(name, area_cap)
+    def capacitor(name, area_cap, cls = nil)
       self._context("capacitor") do
-        RBA::DeviceExtractorCapacitor::new(name, area_cap)
+        RBA::DeviceExtractorCapacitor::new(name, area_cap, _make_factory(cls))
       end
     end
 
@@ -498,6 +552,7 @@ module DRC
     # @brief Supplies the capacitor extractor class that includes a bulk terminal
     # @name capacitor_with_bulk
     # @synopsis capacitor_with_bulk(name, area_cap)
+    # @synopsis capacitor_with_bulk(name, area_cap, class)
     # Use this class with \extract_devices to specify extraction of a capacitor 
     # with a bulk terminal.
     # The area_cap argument is the capacitance in Farad per square micrometer.
@@ -505,9 +560,9 @@ module DRC
     # See RBA::DeviceExtractorCapacitorWithBulk for more details
     # about this extractor.
 
-    def capacitor_with_bulk(name, area_cap)
+    def capacitor_with_bulk(name, area_cap, cls = nil)
       self._context("capacitor_with_bulk") do
-        RBA::DeviceExtractorCapacitorWithBulk::new(name, area_cap)
+        RBA::DeviceExtractorCapacitorWithBulk::new(name, area_cap, _make_factory(cls))
       end
     end
 
diff --git a/src/lay/lay/doc/manual/lvs_device_extractors.xml b/src/lay/lay/doc/manual/lvs_device_extractors.xml
index e1200800f..7cf6449e2 100644
--- a/src/lay/lay/doc/manual/lvs_device_extractors.xml
+++ b/src/lay/lay/doc/manual/lvs_device_extractors.xml
@@ -376,5 +376,33 @@ dc.enable_parameter("L", true)
   fully enabled parameters.
   </p>
 
+  <p>
+  Another way of customizing the built-in device extractors is to
+  supply a custom device class. The following code creates a new 
+  resistor class which changes the preconfigured device parameter definitions
+  to enable "W" and "L".
+  </p>
+
+  <pre>class MyResistor &lt; RBA::DeviceClassResistor
+  def initialize
+    super
+    enable_parameter("W", true)
+    enable_parameter("L", true)
+  end
+end
+
+...
+
+extract_devices(resistor("RES", 1, MyResistor), ...)
+</pre>
+
+  <p>
+  The effect of this code is the same than the first one, but using a custom
+  device class opens the option to supply additional parameters for example
+  or to implement some entirely new device while using the extraction
+  mechanics of the resistor extractor. The only requirement is compatibility of
+  the parameter and terminal definitions.
+  </p>
+
 </doc>
 
diff --git a/src/lvs/unit_tests/lvsSimpleTests.cc b/src/lvs/unit_tests/lvsSimpleTests.cc
index 6d054e461..304aa9dd5 100644
--- a/src/lvs/unit_tests/lvsSimpleTests.cc
+++ b/src/lvs/unit_tests/lvsSimpleTests.cc
@@ -206,8 +206,14 @@ TEST(23_issue709)
   run_test (_this, "empty_subcells", "empty_subcells.gds");
 }
 
-//  empty gds
 TEST(24_issue806)
 {
   run_test (_this, "custom_compare", "custom_compare.gds");
 }
+
+TEST(25_enableWandL)
+{
+  run_test (_this, "enable_wl1", "resistor.gds");
+  run_test (_this, "enable_wl2", "resistor.gds");
+  run_test (_this, "enable_wl3", "resistor.gds");
+}
diff --git a/testdata/lvs/enable_wl1.cir b/testdata/lvs/enable_wl1.cir
new file mode 100644
index 000000000..2dbc8c321
--- /dev/null
+++ b/testdata/lvs/enable_wl1.cir
@@ -0,0 +1,11 @@
+* Extracted by KLayout
+
+* cell Rre
+* pin gnd!
+* pin vdd!
+.SUBCKT Rre 1 2
+* net 1 gnd!
+* net 2 vdd!
+* device instance $1 r0 *1 8.43,1.51 RR1
+R$1 1 2 RR1 10 W=0.6 L=6
+.ENDS Rre
diff --git a/testdata/lvs/enable_wl1.lvs b/testdata/lvs/enable_wl1.lvs
new file mode 100644
index 000000000..a58903723
--- /dev/null
+++ b/testdata/lvs/enable_wl1.lvs
@@ -0,0 +1,52 @@
+
+# test spice writer delegate on this occasion
+class MyWriterDelegate < RBA::NetlistSpiceWriterDelegate
+  def write_device(device)
+    if device.device_class.name == "RR1"
+      line = "R"
+      line += format_name(device.expanded_name)
+      line += " "
+      line += net_to_string(device.net_for_terminal("A"))
+      line += " "
+      line += net_to_string(device.net_for_terminal("B"))
+      line += " "
+      line += format_name(device.device_class.name)
+      line += " "
+      line += "%.12g" % device.parameter("R")
+      line += " W="
+      line += "%.12g" % device.parameter("W")
+      line += " L="
+      line += "%.12g" % device.parameter("L")
+      emit_line(line) 
+    else
+      super
+    end
+  end
+end
+
+source($lvs_test_source)
+report_lvs($lvs_test_target_lvsdb, true)
+target_netlist($lvs_test_target_cir, write_spice(MyWriterDelegate::new), "Extracted by KLayout")
+
+schematic("resistor.cir")
+
+deep
+
+contact     = input(15, 0)
+metal1      = input(16, 0)  
+metal1_ver  = input(16, 5)
+metal1_lbl  = labels(16, 3) 
+res = metal1 & metal1_ver
+metal1_not_res = metal1 - metal1_ver
+
+dc = extract_devices(resistor("RR1", 1),  { "R" => res , "C" => metal1_not_res})
+dc.enable_parameter("W", true)
+dc.enable_parameter("L", true)
+
+connect(contact, metal1_not_res)
+connect(metal1_not_res, metal1_lbl)
+
+align
+netlist.simplify
+compare
+
diff --git a/testdata/lvs/enable_wl1.lvsdb b/testdata/lvs/enable_wl1.lvsdb
new file mode 100644
index 000000000..67695b612
--- /dev/null
+++ b/testdata/lvs/enable_wl1.lvsdb
@@ -0,0 +1,118 @@
+#%lvsdb-klayout
+
+# Layout
+layout(
+ top(Rre)
+ unit(0.001)
+
+ # Layer section
+ # This section lists the mask layers (drawing or derived) and their connections.
+
+ # Mask layers
+ layer(l3 '15/0')
+ layer(l4 '16/3')
+ layer(l1)
+
+ # Mask layer connectivity
+ connect(l3 l3 l1)
+ connect(l4 l1)
+ connect(l1 l3 l4 l1)
+
+ # Device class section
+ class(RR1 RES
+  param(L 1 0)
+  param(W 1 0)
+ )
+
+ # Device abstracts section
+ # Device abstracts list the pin shapes of the devices.
+ device(D$RR1 RR1
+  terminal(A
+   rect(l1 (-3160 -300) (160 600))
+  )
+  terminal(B
+   rect(l1 (3000 -300) (160 600))
+  )
+ )
+
+ # Circuit section
+ # Circuits are the hierarchical building blocks of the netlist.
+ circuit(Rre
+
+  # Circuit boundary
+  rect((5270 1210) (6320 600))
+
+  # Nets with their geometries
+  net(1 name('gnd!')
+   rect(l3 (5295 1230) (120 560))
+   text(l4 'gnd!' (-60 -60))
+   rect(l1 (-70 -505) (125 570))
+   rect(l1 (-140 -585) (160 600))
+  )
+  net(2 name('vdd!')
+   rect(l3 (11455 1240) (120 540))
+   text(l4 'vdd!' (-65 -60))
+   rect(l1 (-65 -495) (125 560))
+   rect(l1 (-140 -575) (160 600))
+  )
+
+  # Outgoing pins and their connections to nets
+  pin(1 name('gnd!'))
+  pin(2 name('vdd!'))
+
+  # Devices and their connections
+  device(1 D$RR1
+   location(8430 1510)
+   param(R 10)
+   param(L 6)
+   param(W 0.6)
+   param(A 3.6)
+   param(P 13.2)
+   terminal(A 1)
+   terminal(B 2)
+  )
+
+ )
+)
+
+# Reference netlist
+reference(
+
+ # Device class section
+ class(RR1 RES)
+
+ # Circuit section
+ # Circuits are the hierarchical building blocks of the netlist.
+ circuit(RRE
+
+  # Nets
+  net(1 name('VDD!'))
+  net(2 name('GND!'))
+
+  # Devices and their connections
+  device(1 RR1
+   name(R0)
+   param(R 10)
+   param(L 6)
+   param(W 0.6)
+   param(A 0)
+   param(P 0)
+   terminal(A 1)
+   terminal(B 2)
+  )
+
+ )
+)
+
+# Cross reference
+xref(
+ circuit(Rre RRE match
+  xref(
+   net(1 2 match)
+   net(2 1 match)
+   pin(0 () match)
+   pin(1 () match)
+   device(1 1 match)
+  )
+ )
+)
diff --git a/testdata/lvs/enable_wl2.cir b/testdata/lvs/enable_wl2.cir
new file mode 100644
index 000000000..5ce133250
--- /dev/null
+++ b/testdata/lvs/enable_wl2.cir
@@ -0,0 +1,11 @@
+* Extracted by KLayout
+
+* cell Rre
+* pin gnd!
+* pin vdd!
+.SUBCKT Rre 1 2
+* net 1 gnd!
+* net 2 vdd!
+* device instance $1 r0 *1 8.43,1.51 RR1
+R$1 1 2 10 RR1 L=6U W=0.6U A=3.6P P=13.2U
+.ENDS Rre
diff --git a/testdata/lvs/enable_wl2.lvs b/testdata/lvs/enable_wl2.lvs
new file mode 100644
index 000000000..945a89294
--- /dev/null
+++ b/testdata/lvs/enable_wl2.lvs
@@ -0,0 +1,33 @@
+
+source($lvs_test_source)
+report_lvs($lvs_test_target_lvsdb, true)
+target_netlist($lvs_test_target_cir, write_spice, "Extracted by KLayout")
+
+schematic("resistor.cir")
+
+deep
+
+contact     = input(15, 0)
+metal1      = input(16, 0)  
+metal1_ver  = input(16, 5)
+metal1_lbl  = labels(16, 3) 
+res = metal1 & metal1_ver
+metal1_not_res = metal1 - metal1_ver
+
+class MyResistorClass < RBA::DeviceClassResistor
+  def initialize
+    super
+    enable_parameter("W", true)
+    enable_parameter("L", true)
+  end
+end
+
+extract_devices(resistor("RR1", 1, MyResistorClass), { "R" => res , "C" => metal1_not_res})
+
+connect(contact, metal1_not_res)
+connect(metal1_not_res, metal1_lbl)
+
+align
+netlist.simplify
+compare
+
diff --git a/testdata/lvs/enable_wl2.lvsdb b/testdata/lvs/enable_wl2.lvsdb
new file mode 100644
index 000000000..67695b612
--- /dev/null
+++ b/testdata/lvs/enable_wl2.lvsdb
@@ -0,0 +1,118 @@
+#%lvsdb-klayout
+
+# Layout
+layout(
+ top(Rre)
+ unit(0.001)
+
+ # Layer section
+ # This section lists the mask layers (drawing or derived) and their connections.
+
+ # Mask layers
+ layer(l3 '15/0')
+ layer(l4 '16/3')
+ layer(l1)
+
+ # Mask layer connectivity
+ connect(l3 l3 l1)
+ connect(l4 l1)
+ connect(l1 l3 l4 l1)
+
+ # Device class section
+ class(RR1 RES
+  param(L 1 0)
+  param(W 1 0)
+ )
+
+ # Device abstracts section
+ # Device abstracts list the pin shapes of the devices.
+ device(D$RR1 RR1
+  terminal(A
+   rect(l1 (-3160 -300) (160 600))
+  )
+  terminal(B
+   rect(l1 (3000 -300) (160 600))
+  )
+ )
+
+ # Circuit section
+ # Circuits are the hierarchical building blocks of the netlist.
+ circuit(Rre
+
+  # Circuit boundary
+  rect((5270 1210) (6320 600))
+
+  # Nets with their geometries
+  net(1 name('gnd!')
+   rect(l3 (5295 1230) (120 560))
+   text(l4 'gnd!' (-60 -60))
+   rect(l1 (-70 -505) (125 570))
+   rect(l1 (-140 -585) (160 600))
+  )
+  net(2 name('vdd!')
+   rect(l3 (11455 1240) (120 540))
+   text(l4 'vdd!' (-65 -60))
+   rect(l1 (-65 -495) (125 560))
+   rect(l1 (-140 -575) (160 600))
+  )
+
+  # Outgoing pins and their connections to nets
+  pin(1 name('gnd!'))
+  pin(2 name('vdd!'))
+
+  # Devices and their connections
+  device(1 D$RR1
+   location(8430 1510)
+   param(R 10)
+   param(L 6)
+   param(W 0.6)
+   param(A 3.6)
+   param(P 13.2)
+   terminal(A 1)
+   terminal(B 2)
+  )
+
+ )
+)
+
+# Reference netlist
+reference(
+
+ # Device class section
+ class(RR1 RES)
+
+ # Circuit section
+ # Circuits are the hierarchical building blocks of the netlist.
+ circuit(RRE
+
+  # Nets
+  net(1 name('VDD!'))
+  net(2 name('GND!'))
+
+  # Devices and their connections
+  device(1 RR1
+   name(R0)
+   param(R 10)
+   param(L 6)
+   param(W 0.6)
+   param(A 0)
+   param(P 0)
+   terminal(A 1)
+   terminal(B 2)
+  )
+
+ )
+)
+
+# Cross reference
+xref(
+ circuit(Rre RRE match
+  xref(
+   net(1 2 match)
+   net(2 1 match)
+   pin(0 () match)
+   pin(1 () match)
+   device(1 1 match)
+  )
+ )
+)
diff --git a/testdata/lvs/enable_wl3.cir b/testdata/lvs/enable_wl3.cir
new file mode 100644
index 000000000..5ce133250
--- /dev/null
+++ b/testdata/lvs/enable_wl3.cir
@@ -0,0 +1,11 @@
+* Extracted by KLayout
+
+* cell Rre
+* pin gnd!
+* pin vdd!
+.SUBCKT Rre 1 2
+* net 1 gnd!
+* net 2 vdd!
+* device instance $1 r0 *1 8.43,1.51 RR1
+R$1 1 2 10 RR1 L=6U W=0.6U A=3.6P P=13.2U
+.ENDS Rre
diff --git a/testdata/lvs/enable_wl3.lvs b/testdata/lvs/enable_wl3.lvs
new file mode 100644
index 000000000..8f5405307
--- /dev/null
+++ b/testdata/lvs/enable_wl3.lvs
@@ -0,0 +1,33 @@
+
+source($lvs_test_source)
+report_lvs($lvs_test_target_lvsdb, true)
+target_netlist($lvs_test_target_cir, write_spice, "Extracted by KLayout")
+
+schematic("resistor2.cir")
+
+deep
+
+contact     = input(15, 0)
+metal1      = input(16, 0)  
+metal1_ver  = input(16, 5)
+metal1_lbl  = labels(16, 3) 
+res = metal1 & metal1_ver
+metal1_not_res = metal1 - metal1_ver
+
+class MyResistorClass < RBA::DeviceClassResistor
+  def initialize
+    super
+    enable_parameter("W", true)
+    enable_parameter("L", true)
+  end
+end
+
+extract_devices(resistor("RR1", 1, MyResistorClass), { "R" => res , "C" => metal1_not_res})
+
+connect(contact, metal1_not_res)
+connect(metal1_not_res, metal1_lbl)
+
+align
+netlist.simplify
+compare
+
diff --git a/testdata/lvs/enable_wl3.lvsdb b/testdata/lvs/enable_wl3.lvsdb
new file mode 100644
index 000000000..947fc54ac
--- /dev/null
+++ b/testdata/lvs/enable_wl3.lvsdb
@@ -0,0 +1,121 @@
+#%lvsdb-klayout
+
+# Layout
+layout(
+ top(Rre)
+ unit(0.001)
+
+ # Layer section
+ # This section lists the mask layers (drawing or derived) and their connections.
+
+ # Mask layers
+ layer(l3 '15/0')
+ layer(l4 '16/3')
+ layer(l1)
+
+ # Mask layer connectivity
+ connect(l3 l3 l1)
+ connect(l4 l1)
+ connect(l1 l3 l4 l1)
+
+ # Device class section
+ class(RR1 RES
+  param(L 1 0)
+  param(W 1 0)
+ )
+
+ # Device abstracts section
+ # Device abstracts list the pin shapes of the devices.
+ device(D$RR1 RR1
+  terminal(A
+   rect(l1 (-3160 -300) (160 600))
+  )
+  terminal(B
+   rect(l1 (3000 -300) (160 600))
+  )
+ )
+
+ # Circuit section
+ # Circuits are the hierarchical building blocks of the netlist.
+ circuit(Rre
+
+  # Circuit boundary
+  rect((5270 1210) (6320 600))
+
+  # Nets with their geometries
+  net(1 name('gnd!')
+   rect(l3 (5295 1230) (120 560))
+   text(l4 'gnd!' (-60 -60))
+   rect(l1 (-70 -505) (125 570))
+   rect(l1 (-140 -585) (160 600))
+  )
+  net(2 name('vdd!')
+   rect(l3 (11455 1240) (120 540))
+   text(l4 'vdd!' (-65 -60))
+   rect(l1 (-65 -495) (125 560))
+   rect(l1 (-140 -575) (160 600))
+  )
+
+  # Outgoing pins and their connections to nets
+  pin(1 name('gnd!'))
+  pin(2 name('vdd!'))
+
+  # Devices and their connections
+  device(1 D$RR1
+   location(8430 1510)
+   param(R 10)
+   param(L 6)
+   param(W 0.6)
+   param(A 3.6)
+   param(P 13.2)
+   terminal(A 1)
+   terminal(B 2)
+  )
+
+ )
+)
+
+# Reference netlist
+reference(
+
+ # Device class section
+ class(RR1 RES)
+
+ # Circuit section
+ # Circuits are the hierarchical building blocks of the netlist.
+ circuit(RRE
+
+  # Nets
+  net(1 name('VDD!'))
+  net(2 name('GND!'))
+
+  # Devices and their connections
+  device(1 RR1
+   name(R0)
+   param(R 10)
+   param(L 7)
+   param(W 0.6)
+   param(A 0)
+   param(P 0)
+   terminal(A 1)
+   terminal(B 2)
+  )
+
+ )
+)
+
+# Cross reference
+xref(
+ circuit(Rre RRE nomatch
+  xref(
+   net(() 2 mismatch)
+   net(() 1 mismatch)
+   net(1 () mismatch)
+   net(2 () mismatch)
+   pin(0 () match)
+   pin(1 () match)
+   device(() 1 mismatch)
+   device(1 () mismatch)
+  )
+ )
+)
diff --git a/testdata/lvs/resistor.cir b/testdata/lvs/resistor.cir
new file mode 100644
index 000000000..c210ac37c
--- /dev/null
+++ b/testdata/lvs/resistor.cir
@@ -0,0 +1,4 @@
+.SUBCKT Rre 
+RR0 vdd! gnd! 10 RR1 W=600n L=6u M=1
+.ENDS
+
diff --git a/testdata/lvs/resistor.gds b/testdata/lvs/resistor.gds
new file mode 100644
index 000000000..aa2b5869b
Binary files /dev/null and b/testdata/lvs/resistor.gds differ
diff --git a/testdata/lvs/resistor2.cir b/testdata/lvs/resistor2.cir
new file mode 100644
index 000000000..38882671e
--- /dev/null
+++ b/testdata/lvs/resistor2.cir
@@ -0,0 +1,4 @@
+.SUBCKT Rre 
+RR0 vdd! gnd! 10 RR1 W=600n L=7u M=1
+.ENDS
+
diff --git a/testdata/ruby/dbNetlist.rb b/testdata/ruby/dbNetlist.rb
index bb1d34570..dc09d7f4b 100644
--- a/testdata/ruby/dbNetlist.rb
+++ b/testdata/ruby/dbNetlist.rb
@@ -331,6 +331,8 @@ class DBNetlist_TestClass < TestBase
     assert_equal(net.terminal_count, 1)
 
     assert_equal(d1.net_for_terminal(1).name, "NET")
+    assert_equal(d1.net_for_terminal("B").name, "NET")
+    assert_equal(d1.net_for_terminal("X").inspect, "nil")
     assert_equal(d1.net_for_terminal(0).inspect, "nil")
 
     d1.disconnect_terminal("B")