From 666cdeadc5ef8061a524496d15b7c2ca8d7d8e54 Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@koefferlein.de>
Date: Sat, 28 Mar 2020 12:29:53 +0100
Subject: [PATCH] MERGE: documentation enhancements for LVS/DRC

---
 scripts/extract_doc.rb                        |   2 +-
 src/db/db/gsiDeclDbNetlistDeviceExtractor.cc  | 211 ++++++--
 src/drc/drc/built-in-macros/_drc_engine.rb    |  41 +-
 src/drc/drc/built-in-macros/_drc_netter.rb    |  18 +-
 src/lay/lay/doc/about/drc_ref_global.xml      | 293 +++++-----
 src/lay/lay/doc/about/drc_ref_layer.xml       | 512 +++++++++---------
 src/lay/lay/doc/about/drc_ref_netter.xml      |  54 +-
 src/lay/lay/doc/about/drc_ref_source.xml      |  60 +-
 src/lay/lay/doc/about/lvs_ref_global.xml      |  60 +-
 src/lay/lay/doc/about/lvs_ref_netter.xml      |  72 ++-
 .../lay/doc/manual/lvs_device_extractors.xml  |  14 +-
 11 files changed, 795 insertions(+), 542 deletions(-)

diff --git a/scripts/extract_doc.rb b/scripts/extract_doc.rb
index 54e51bfb1..eb9a149d8 100755
--- a/scripts/extract_doc.rb
+++ b/scripts/extract_doc.rb
@@ -160,9 +160,9 @@ HEAD
       item.name || raise("Missing @name for item #{item_key}")
       item.brief || raise("Missing @brief for item #{item_key}")
 
+      doc += "<a name=\"" + escape(self.mod, item.name) + "\"/>"
       doc += "<h2>\"" + escape(self.mod, item.name) + "\" - " + escape(self.mod, item.brief) + "</h2>\n"
       doc += "<keyword name=\"" + escape(self.mod, item.name) + "\"/>\n"
-      doc += "<a name=\"" + escape(self.mod, item.name) + "\"/>"
       if ! item.synopsis.empty?
         doc += "<p>Usage:</p>\n"
         doc += "<ul>\n"
diff --git a/src/db/db/gsiDeclDbNetlistDeviceExtractor.cc b/src/db/db/gsiDeclDbNetlistDeviceExtractor.cc
index 2fb2a6ba7..9a0bb6e16 100644
--- a/src/db/db/gsiDeclDbNetlistDeviceExtractor.cc
+++ b/src/db/db/gsiDeclDbNetlistDeviceExtractor.cc
@@ -421,13 +421,31 @@ Class<db::NetlistDeviceExtractorMOS3Transistor> decl_NetlistDeviceExtractorMOS3T
   "conductive layer.\n"
   "\n"
   "The device class produced by this extractor is \\DeviceClassMOS3Transistor.\n"
-  "The extractor extracts the six parameters of this class: L, W, AS, AD, PS and PD.\n"
   "\n"
-  "In strict mode, the device recognition layer names are 'S' (source), 'D' (drain) and 'G' (gate).\n"
-  "Otherwise, they are 'SD' (source/drain) and 'G' (gate).\n"
-  "The terminal output layer names are 'tS' (source), 'tG' (gate) and 'tD' (drain).\n"
+  "The extractor delivers six parameters:\n"
   "\n"
-  "The diffusion area is distributed on the number of gates connecting to\n"
+  "@ul\n"
+  "@li 'L' - the gate length in micrometer units @/li\n"
+  "@li 'W' - the gate width in micrometer units @/li\n"
+  "@li 'AS' and 'AD' - the source and drain region areas in square micrometers @/li\n"
+  "@li 'PS' and 'PD' - the source and drain region perimeters in micrometer units @/li\n"
+  "@/ul\n"
+  "\n"
+  "The device layer names are:\n"
+  "\n"
+  "@ul\n"
+  "@li In strict mode: 'S' (source), 'D' (drain) and 'G' (gate). @/li\n"
+  "@li In non-strict mode: 'SD' (source and drain) and 'G' (gate). @/li\n"
+  "@/ul\n"
+  "\n"
+  "The terminals are output on these layers:\n"
+  "@ul\n"
+  "@li 'tS' - source. Default output is 'S' (strict mode) or 'SD' (otherwise). @/li\n"
+  "@li 'tD' - drain. Default output is 'D' (strict mode) or 'SD' (otherwise). @/li\n"
+  "@li 'tG' - gate. Default output is 'G'. @/li\n"
+  "@/ul\n"
+  "\n"
+  "The source/drain (diffusion) area is distributed on the number of gates connecting to\n"
   "the particular source or drain area.\n"
   "\n"
   "This class is a closed one and methods cannot be reimplemented. To reimplement "
@@ -451,12 +469,23 @@ Class<db::NetlistDeviceExtractorMOS4Transistor> decl_NetlistDeviceExtractorMOS4T
   "It is based on the \\DeviceExtractorMOS3Transistor class with the extension of a bulk terminal "
   "and corresponding bulk terminal output (annotation) layer.\n"
   "\n"
-  "The bulk terminal layer ('tB') can be an empty layer representing the substrate.\n"
-  "In this use mode the bulk terminal shapes will be produced on the 'tB' layer. This\n"
-  "layer then needs to be connected to a global net to establish the net connection.\n"
+  "The parameters of a MOS4 device are the same than for MOS3 devices. For the device "
+  "layers the bulk layer is added.\n"
+  "\n"
+  "@ul\n"
+  "@li 'B' (bulk) - currently this layer is not used and can be empty. @/li\n"
+  "@/ul\n"
+  "\n"
+  "The bulk terminals are output on this layer:\n"
+  "@ul\n"
+  "@li 'tB' - bulk terminal (a copy of the gate shape). Default output is 'B'. @/li\n"
+  "@/ul\n"
+  "\n"
+  "The bulk terminal layer can be empty. In this case, it needs \n"
+  "to be connected to a global net to establish the net connection.\n"
   "\n"
   "The device class produced by this extractor is \\DeviceClassMOS4Transistor.\n"
-  "The "
+  "\n"
   "This class is a closed one and methods cannot be reimplemented. To reimplement "
   "specific methods, see \\DeviceExtractor.\n"
   "\n"
@@ -487,10 +516,25 @@ Class<db::NetlistDeviceExtractorResistor> decl_NetlistDeviceExtractorResistor (d
   "'R = L / W * sheet_rho'.\n"
   "\n"
   "The device class produced by this extractor is \\DeviceClassResistor.\n"
-  "The extractor extracts the three parameters of this class: R, A and P.\n"
+  "The extractor produces three parameters:\n"
   "\n"
-  "The device recognition layer names are 'R' (resistor) and 'C' (contacts).\n"
-  "The terminal output layer names are 'tA' (terminal A) and 'tB' (terminal B).\n"
+  "@ul\n"
+  "@li 'R' - the resistance in Ohm @/li\n"
+  "@li 'A' - the resistor's area in square micrometer units @/li\n"
+  "@li 'P' - the resistor's perimeter in micrometer units @/li\n"
+  "@/ul\n"
+  "\n"
+  "The device layer names are:\n"
+  "\n"
+  "@ul\n"
+  "@li 'R' - resistor path. This is the geometry that defines the resistor's current path. @/li\n"
+  "@li 'C' - contacts. These areas form the contact regions at the ends of the resistor path. @/li\n"
+  "@/ul\n"
+  "\n"
+  "The terminals are output on these layers:\n"
+  "@ul\n"
+  "@li 'tA', 'tB' - the two terminals of the resistor. @/li\n"
+  "@/ul\n"
   "\n"
   "This class is a closed one and methods cannot be reimplemented. To reimplement "
   "specific methods, see \\DeviceExtractor.\n"
@@ -512,16 +556,30 @@ Class<db::NetlistDeviceExtractorResistorWithBulk> decl_NetlistDeviceExtractorRes
   "This class supplies the generic extractor for a resistor device including a bulk terminal.\n"
   "The device is defined the same way than devices are defined for \\DeviceExtractorResistor.\n"
   "\n"
-  "In addition, a bulk terminal layer must be provided.\n"
-  "The bulk terminal layer can be an empty layer representing the substrate.\n"
-  "In this use mode the bulk terminal shapes will be produced on the 'tW' layer. This\n"
-  "layer then needs to be connected to a global net to establish the net connection.\n"
-  "\n"
   "The device class produced by this extractor is \\DeviceClassResistorWithBulk.\n"
-  "The extractor extracts the three parameters of this class: R, A and P.\n"
+  "The extractor produces three parameters:\n"
   "\n"
-  "The device recognition layer names are 'R' (resistor), 'C' (contacts) and 'W' (well, bulk).\n"
-  "The terminal output layer names are 'tA' (terminal A), 'tB' (terminal B) and 'tW' (well, bulk).\n"
+  "@ul\n"
+  "@li 'R' - the resistance in Ohm @/li\n"
+  "@li 'A' - the resistor's area in square micrometer units @/li\n"
+  "@li 'P' - the resistor's perimeter in micrometer units @/li\n"
+  "@/ul\n"
+  "\n"
+  "The device layer names are:\n"
+  "\n"
+  "@ul\n"
+  "@li 'R' - resistor path. This is the geometry that defines the resistor's current path. @/li\n"
+  "@li 'C' - contacts. These areas form the contact regions at the ends of the resistor path. @/li\n"
+  "@li 'W' - well, bulk. Currently this layer is ignored for the extraction and can be empty. @/li\n"
+  "@/ul\n"
+  "\n"
+  "The terminals are output on these layers:\n"
+  "@ul\n"
+  "@li 'tA', 'tB' - the two terminals of the resistor. @/li\n"
+  "@li 'tW' - the bulk terminal (copy of the resistor area). @/li\n"
+  "@/ul\n"
+  "\n"
+  "The bulk terminal layer can be an empty layer representing the substrate. In this case, it needs to be connected globally.\n"
   "\n"
   "This class is a closed one and methods cannot be reimplemented. To reimplement "
   "specific methods, see \\DeviceExtractor.\n"
@@ -545,11 +603,28 @@ Class<db::NetlistDeviceExtractorCapacitor> decl_NetlistDeviceExtractorCapacitor
   "The capacitance is computed from the overlapping area of the plates "
   "using 'C = A * area_cap' (area_cap is the capacitance per square micrometer area).\n"
   "\n"
-  "The device class produced by this extractor is \\DeviceClassCapacitor.\n"
-  "The extractor extracts the three parameters of this class: C, A and P.\n"
+  "Although 'area_cap' can be given in any unit, Farad should be preferred as this is the "
+  "convention used for output into a netlist.\n"
   "\n"
-  "The device recognition layer names are 'P1' (plate 1) and 'P2' (plate 2).\n"
-  "The terminal output layer names are 'tA' (terminal A) and 'tB' (terminal B).\n"
+  "The device class produced by this extractor is \\DeviceClassCapacitor.\n"
+  "The extractor produces three parameters:\n"
+  "\n"
+  "@ul\n"
+  "@li 'C' - the capacitance @/li\n"
+  "@li 'A' - the capacitor's area in square micrometer units @/li\n"
+  "@li 'P' - the capacitor's perimeter in micrometer units @/li\n"
+  "@/ul\n"
+  "\n"
+  "The device layer names are:\n"
+  "\n"
+  "@ul\n"
+  "@li 'P1', 'P2' - the two plates. @/li\n"
+  "@/ul\n"
+  "\n"
+  "The terminals are output on these layers:\n"
+  "@ul\n"
+  "@li 'tA', 'tB' - the two terminals. Defaults to 'P1' and 'P2'. @/li\n"
+  "@/ul\n"
   "\n"
   "This class is a closed one and methods cannot be reimplemented. To reimplement "
   "specific methods, see \\DeviceExtractor.\n"
@@ -571,16 +646,29 @@ Class<db::NetlistDeviceExtractorCapacitorWithBulk> decl_NetlistDeviceExtractorCa
   "This class supplies the generic extractor for a capacitor device including a bulk terminal.\n"
   "The device is defined the same way than devices are defined for \\DeviceExtractorCapacitor.\n"
   "\n"
-  "In addition, a bulk terminal layer must be provided.\n"
-  "The bulk terminal layer can be an empty layer representing the substrate.\n"
-  "In this use mode the bulk terminal shapes will be produced on the 'tW' layer. This\n"
-  "layer then needs to be connected to a global net to establish the net connection.\n"
-  "\n"
   "The device class produced by this extractor is \\DeviceClassCapacitorWithBulk.\n"
-  "The extractor extracts the three parameters of this class: C, A and P.\n"
+  "The extractor produces three parameters:\n"
   "\n"
-  "The device recognition layer names are 'P1' (plate 1), 'P2' (plate 2) and 'W' (well, bulk).\n"
-  "The terminal output layer names are 'tA' (terminal A), 'tB' (terminal B) and 'tW' (well, bulk).\n"
+  "@ul\n"
+  "@li 'C' - the capacitance @/li\n"
+  "@li 'A' - the capacitor's area in square micrometer units @/li\n"
+  "@li 'P' - the capacitor's perimeter in micrometer units @/li\n"
+  "@/ul\n"
+  "\n"
+  "The device layer names are:\n"
+  "\n"
+  "@ul\n"
+  "@li 'P1', 'P2' - the two plates. @/li\n"
+  "@li 'W' - well, bulk. Currently this layer is ignored for the extraction and can be empty. @/li\n"
+  "@/ul\n"
+  "\n"
+  "The terminals are output on these layers:\n"
+  "@ul\n"
+  "@li 'tA', 'tB' - the two terminals. Defaults to 'P1' and 'P2'. @/li\n"
+  "@li 'tW' - the bulk terminal (copy of the resistor area). @/li\n"
+  "@/ul\n"
+  "\n"
+  "The bulk terminal layer can be an empty layer representing the substrate. In this case, it needs to be connected globally.\n"
   "\n"
   "This class is a closed one and methods cannot be reimplemented. To reimplement "
   "specific methods, see \\DeviceExtractor.\n"
@@ -612,10 +700,28 @@ Class<db::NetlistDeviceExtractorBJT3Transistor> decl_dbNetlistDeviceExtractorBJT
   "to form the net connection.\n"
   "\n"
   "The device class produced by this extractor is \\DeviceClassBJT3Transistor.\n"
-  "The extractor extracts the two parameters of this class: AE and PE.\n"
+  "The extractor delivers these parameters:\n"
   "\n"
-  "The device recognition layer names are 'C' (collector), 'B' (base) and 'E' (emitter).\n"
-  "The terminal output layer names are 'tC' (collector), 'tB' (base) and 'tE' (emitter).\n"
+  "@ul\n"
+  "@li 'AE', 'AB' and 'AC' - the emitter, base and collector areas in square micrometer units @/li\n"
+  "@li 'PE', 'PB' and 'PC' - the emitter, base and collector perimeters in micrometer units @/li\n"
+  "@li 'NE' - emitter count (initially 1 but increases when devices are combined) @/li\n"
+  "@/ul\n"
+  "\n"
+  "The device layer names are:\n"
+  "\n"
+  "@ul\n"
+  "@li 'E' - emitter. @/li\n"
+  "@li 'B' - base. @/li\n"
+  "@li 'C' - collector. @/li\n"
+  "@/ul\n"
+  "\n"
+  "The terminals are output on these layers:\n"
+  "@ul\n"
+  "@li 'tE' - emitter. Default output is 'E'. @/li\n"
+  "@li 'tB' - base. Default output is 'B'. @/li\n"
+  "@li 'tC' - collector. Default output is 'C'. @/li\n"
+  "@/ul\n"
   "\n"
   "This class is a closed one and methods cannot be reimplemented. To reimplement "
   "specific methods, see \\DeviceExtractor.\n"
@@ -638,6 +744,13 @@ Class<db::NetlistDeviceExtractorBJT4Transistor> decl_NetlistDeviceExtractorBJT4T
   "It is based on the \\DeviceExtractorBJT3Transistor class with the extension of a substrate terminal "
   "and corresponding substrate terminal output (annotation) layer.\n"
   "\n"
+  "Two new layers are introduced:\n"
+  "\n"
+  "@ul\n"
+  "@li 'S' - the bulk (substrate) layer. Currently this layer is ignored and can be empty. @/li"
+  "@li 'tS' - the bulk terminal output layer (defaults to 'S'). @/li"
+  "@/ul\n"
+  "\n"
   "The bulk terminal layer ('tS') can be an empty layer representing the wafer substrate.\n"
   "In this use mode the substrate terminal shapes will be produced on the 'tS' layer. This\n"
   "layer then needs to be connected to a global net to establish the net connection.\n"
@@ -666,13 +779,29 @@ Class<db::NetlistDeviceExtractorDiode> decl_NetlistDeviceExtractorDiode (decl_db
   "the diode. The p-type layer forms the anode, the n-type layer\n"
   "the cathode.\n"
   "\n"
-  "The device class produced by this extractor is DeviceClassDiode.\n"
-  "The extractor extracts the two parameters of this class: A and P.\n"
-  "A is the area of the overlap area and P is the perimeter.\n"
+  "The device class produced by this extractor is \\DeviceClassDiode.\n"
+  "The extractor extracts the two parameters of this class:\n"
   "\n"
-  "The layers are \"P\" and \"N\" for the p and n region respectively.\n"
-  "The terminal output layers are \"tA\" and \"tC\" for anode and \n"
-  "cathode respectively.\n"
+  "@ul\n"
+  "@li 'A' - the diode area in square micrometer units. @/li\n"
+  "@li 'P' - the diode perimeter in micrometer units. @/li\n"
+  "@/ul\n"
+  "\n"
+  "The device layers are:\n"
+  "\n"
+  "@ul\n"
+  "@li 'P' - the p doped area. @/li\n"
+  "@li 'N' - the n doped area. @/li\n"
+  "@/ul\n"
+  "\n"
+  "The diode region is defined by the overlap of p and n regions.\n"
+  "\n"
+  "The terminal output layers are:\n"
+  "\n"
+  "@ul\n"
+  "@li 'tA' - anode. Defaults to 'P'. @/li\n"
+  "@li 'tC' - cathode. Defaults to 'N'. @/li\n"
+  "@/ul\n"
   "\n"
   "This class is a closed one and methods cannot be reimplemented. To reimplement "
   "specific methods, see \\DeviceExtractor.\n"
diff --git a/src/drc/drc/built-in-macros/_drc_engine.rb b/src/drc/drc/built-in-macros/_drc_engine.rb
index 3ebf1bc10..5855454fd 100644
--- a/src/drc/drc/built-in-macros/_drc_engine.rb
+++ b/src/drc/drc/built-in-macros/_drc_engine.rb
@@ -147,7 +147,10 @@ module DRC
     # @name mos3
     # @synopsis mos3(name)
     # Use this class with \extract_devices to specify extraction of a 
-    # three-terminal MOS transistor
+    # three-terminal MOS transistor.
+    #
+    # See RBA::DeviceExtractorMOS3Transistor for more details
+    # about this extractor (non-strict mode applies for 'mos3').
 
     def mos3(name)
       RBA::DeviceExtractorMOS3Transistor::new(name)
@@ -158,7 +161,10 @@ module DRC
     # @name mos4
     # @synopsis mos4(name)
     # Use this class with \extract_devices to specify extraction of a 
-    # four-terminal MOS transistor
+    # four-terminal MOS transistor.
+    #
+    # See RBA::DeviceExtractorMOS4Transistor for more details
+    # about this extractor (non-strict mode applies for 'mos4').
 
     def mos4(name)
       RBA::DeviceExtractorMOS4Transistor::new(name)
@@ -172,6 +178,9 @@ module DRC
     # three-terminal DMOS transistor. A DMOS transistor is essentially
     # the same than a MOS transistor, but source and drain are 
     # separated.
+    #
+    # See RBA::DeviceExtractorMOS3Transistor for more details
+    # about this extractor (strict mode applies for 'dmos3').
 
     def dmos3(name)
       RBA::DeviceExtractorMOS3Transistor::new(name, true)
@@ -185,6 +194,9 @@ module DRC
     # four-terminal DMOS transistor. A DMOS transistor is essentially
     # the same than a MOS transistor, but source and drain are 
     # separated.
+    #
+    # See RBA::DeviceExtractorMOS4Transistor for more details
+    # about this extractor (strict mode applies for 'dmos4').
 
     def dmos4(name)
       RBA::DeviceExtractorMOS4Transistor::new(name, true)
@@ -196,6 +208,9 @@ module DRC
     # @synopsis bjt3(name)
     # 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)
       RBA::DeviceExtractorBJT3Transistor::new(name)
@@ -207,6 +222,9 @@ module DRC
     # @synopsis bjt4(name)
     # 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)
       RBA::DeviceExtractorBJT4Transistor::new(name)
@@ -218,6 +236,9 @@ module DRC
     # @synopsis diode(name)
     # 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)
       RBA::DeviceExtractorDiode::new(name)
@@ -228,7 +249,12 @@ module DRC
     # @name resistor
     # @synopsis resistor(name, sheet_rho)
     # Use this class with \extract_devices to specify extraction of a resistor.
-    # The sheet_rho value is the sheet resistance in ohms/square.
+    #
+    # The sheet_rho value is the sheet resistance in ohms/square. It is used
+    # to compute the resistance from the geometry.
+    #
+    # See RBA::DeviceExtractorResistor for more details
+    # about this extractor.
 
     def resistor(name, sheet_rho)
       RBA::DeviceExtractorResistor::new(name, sheet_rho)
@@ -241,6 +267,9 @@ module DRC
     # 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.
+    #
+    # See RBA::DeviceExtractorResistorWithBulk for more details
+    # about this extractor.
 
     def resistor_with_bulk(name, sheet_rho)
       RBA::DeviceExtractorResistorWithBulk::new(name, sheet_rho)
@@ -252,6 +281,9 @@ module DRC
     # @synopsis capacitor(name, area_cap)
     # 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)
       RBA::DeviceExtractorCapacitor::new(name, area_cap)
@@ -264,6 +296,9 @@ module DRC
     # 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.
+    #
+    # See RBA::DeviceExtractorCapacitorWithBulk for more details
+    # about this extractor.
 
     def capacitor_with_bulk(name, area_cap)
       RBA::DeviceExtractorCapacitorWithBulk::new(name, area_cap)
diff --git a/src/drc/drc/built-in-macros/_drc_netter.rb b/src/drc/drc/built-in-macros/_drc_netter.rb
index 24a0832bb..163f094dd 100644
--- a/src/drc/drc/built-in-macros/_drc_netter.rb
+++ b/src/drc/drc/built-in-macros/_drc_netter.rb
@@ -135,11 +135,27 @@ module DRC
     # class object and the new extractor's name is given.
     # 
     # The device extractor is either an instance of one of the predefined extractor
-    # classes (e.g. obtained from the utility methods such as \mos4) or a custom class. 
+    # classes (e.g. obtained from the utility methods such as \global#mos4) or a custom class. 
     # It provides the
     # algorithms for deriving the device parameters from the device geometry. It needs 
     # several device recognition layers which are passed in the layer hash.
     #
+    # Predefined device extractors are:
+    #
+    # @ul
+    # @li \global#mos3 - A three-terminal MOS transistor @/li
+    # @li \global#mos4 - A four-terminal MOS transistor @/li
+    # @li \global#dmos3 - A three-terminal MOS asymmetric transistor @/li
+    # @li \global#dmos4 - A four-terminal MOS asymmetric transistor @/li
+    # @li \global#bjt3 - A three-terminal bipolar transistor @/li
+    # @li \global#bjt4 - A four-terminal bipolar transistor @/li
+    # @li \global#diode - A planar diode @/li
+    # @li \global#resistor - A resistor @/li
+    # @li \global#resistor_with_bulk - A resistor with a separate bulk terminal @/li
+    # @li \global#capacitor - A capacitor @/li
+    # @li \global#capacitor_with_bulk - A capacitor with a separate bulk terminal @/li
+    # @/ul
+    #
     # Each device class (e.g. n-MOS/p-MOS or high Vt/low Vt) needs it's own instance
     # of device extractor. The device extractor beside the algorithm and specific 
     # extraction settings defines the name of the device to be built.
diff --git a/src/lay/lay/doc/about/drc_ref_global.xml b/src/lay/lay/doc/about/drc_ref_global.xml
index 4d0e8c273..e299fce86 100644
--- a/src/lay/lay/doc/about/drc_ref_global.xml
+++ b/src/lay/lay/doc/about/drc_ref_global.xml
@@ -13,38 +13,44 @@ Most of them are convenience functions that basically act on some default object
 or provide function-like alternatives for the methods.
 </p>
 <h2-index/>
-<h2>"antenna_check" - Performs an antenna check</h2>
+<a name="antenna_check"/><h2>"antenna_check" - Performs an antenna check</h2>
 <keyword name="antenna_check"/>
-<a name="antenna_check"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>antenna_check(gate, metal, ratio, [ diode_specs ... ])</tt></li>
 </ul>
 <p>
 See <a href="/about/drc_ref_netter.xml#antenna_check">Netter#antenna_check</a> for a description of that function.
 </p>
-<h2>"bjt3" - Supplies the BJT3 transistor extractor class</h2>
+<a name="bjt3"/><h2>"bjt3" - Supplies the BJT3 transistor extractor class</h2>
 <keyword name="bjt3"/>
-<a name="bjt3"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>bjt3(name)</tt></li>
 </ul>
 <p>
 Use this class with <a href="#extract_devices">extract_devices</a> to specify extraction of a 
 bipolar junction transistor
+</p><p>
+See <class_doc href="DeviceExtractorBJT3Transistor">DeviceExtractorBJT3Transistor</class_doc> for more details
+about this extractor.
 </p>
-<h2>"bjt4" - Supplies the BJT4 transistor extractor class</h2>
+<a name="bjt4"/><h2>"bjt4" - Supplies the BJT4 transistor extractor class</h2>
 <keyword name="bjt4"/>
-<a name="bjt4"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>bjt4(name)</tt></li>
 </ul>
 <p>
 Use this class with <a href="#extract_devices">extract_devices</a> to specify extraction of a 
 bipolar junction transistor with a substrate terminal
+</p><p>
+See <class_doc href="DeviceExtractorBJT4Transistor">DeviceExtractorBJT4Transistor</class_doc> for more details
+about this extractor.
 </p>
-<h2>"box" - Creates a box object</h2>
+<a name="box"/><h2>"box" - Creates a box object</h2>
 <keyword name="box"/>
-<a name="box"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>box(...)</tt></li>
 </ul>
@@ -52,19 +58,22 @@ bipolar junction transistor with a substrate terminal
 This function creates a box object. The arguments are the same than for the 
 <class_doc href="DBox">DBox</class_doc> constructors.
 </p>
-<h2>"capacitor" - Supplies the capacitor extractor class</h2>
+<a name="capacitor"/><h2>"capacitor" - Supplies the capacitor extractor class</h2>
 <keyword name="capacitor"/>
-<a name="capacitor"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>capacitor(name, area_cap)</tt></li>
 </ul>
 <p>
 Use this class with <a href="#extract_devices">extract_devices</a> to specify extraction of a capacitor.
 The area_cap argument is the capacitance in Farad per square micrometer.
+</p><p>
+See <class_doc href="DeviceExtractorCapacitor">DeviceExtractorCapacitor</class_doc> for more details
+about this extractor.
 </p>
-<h2>"capacitor_with_bulk" - Supplies the capacitor extractor class that includes a bulk terminal</h2>
+<a name="capacitor_with_bulk"/><h2>"capacitor_with_bulk" - Supplies the capacitor extractor class that includes a bulk terminal</h2>
 <keyword name="capacitor_with_bulk"/>
-<a name="capacitor_with_bulk"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>capacitor_with_bulk(name, area_cap)</tt></li>
 </ul>
@@ -72,10 +81,13 @@ The area_cap argument is the capacitance in Farad per square micrometer.
 Use this class with <a href="#extract_devices">extract_devices</a> to specify extraction of a capacitor 
 with a bulk terminal.
 The area_cap argument is the capacitance in Farad per square micrometer.
+</p><p>
+See <class_doc href="DeviceExtractorCapacitorWithBulk">DeviceExtractorCapacitorWithBulk</class_doc> for more details
+about this extractor.
 </p>
-<h2>"cell" - Selects a cell for input on the default source</h2>
+<a name="cell"/><h2>"cell" - Selects a cell for input on the default source</h2>
 <keyword name="cell"/>
-<a name="cell"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>cell(args)</tt></li>
 </ul>
@@ -92,9 +104,9 @@ cell("MACRO")
 l1 = input(1, 0)
 </pre>
 </p>
-<h2>"cheat" - Hierarchy cheats</h2>
+<a name="cheat"/><h2>"cheat" - Hierarchy cheats</h2>
 <keyword name="cheat"/>
-<a name="cheat"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>cheat(args) { block }</tt></li>
 </ul>
@@ -184,18 +196,18 @@ cheat("UNIT_CELL{1,2}") { ... }
 For LVS applications, it's usually sufficient to cheat in the device extraction step. 
 Cheats have been introduced in version 0.26.1.
 </p>
-<h2>"clear_connections" - Clears all connections stored so far</h2>
+<a name="clear_connections"/><h2>"clear_connections" - Clears all connections stored so far</h2>
 <keyword name="clear_connections"/>
-<a name="clear_connections"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>clear_connections</tt></li>
 </ul>
 <p>
 See <a href="/about/drc_ref_netter.xml#clear_connections">Netter#clear_connections</a> for a description of that function.
 </p>
-<h2>"clip" - Specifies clipped input on the default source</h2>
+<a name="clip"/><h2>"clip" - Specifies clipped input on the default source</h2>
 <keyword name="clip"/>
-<a name="clip"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>clip(args)</tt></li>
 </ul>
@@ -211,36 +223,36 @@ clip(0.mm, 0.mm, 0.5.mm, 0.6.mm)
 l1 = input(1, 0)
 </pre>
 </p>
-<h2>"connect" - Specifies a connection between two layers</h2>
+<a name="connect"/><h2>"connect" - Specifies a connection between two layers</h2>
 <keyword name="connect"/>
-<a name="connect"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>connect(a, b)</tt></li>
 </ul>
 <p>
 See <a href="/about/drc_ref_netter.xml#connect">Netter#connect</a> for a description of that function.
 </p>
-<h2>"connect_global" - Specifies a connection to a global net</h2>
+<a name="connect_global"/><h2>"connect_global" - Specifies a connection to a global net</h2>
 <keyword name="connect_global"/>
-<a name="connect_global"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>connect_global(l, name)</tt></li>
 </ul>
 <p>
 See <a href="/about/drc_ref_netter.xml#connect_global">Netter#connect_global</a> for a description of that function.
 </p>
-<h2>"connect_implicit" - Specifies a label pattern for implicit net connections</h2>
+<a name="connect_implicit"/><h2>"connect_implicit" - Specifies a label pattern for implicit net connections</h2>
 <keyword name="connect_implicit"/>
-<a name="connect_implicit"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>connect_implicit(label_pattern)</tt></li>
 </ul>
 <p>
 See <a href="/about/drc_ref_netter.xml#connect_implicit">Netter#connect_implicit</a> for a description of that function.
 </p>
-<h2>"dbu" - Gets or sets the database unit to use</h2>
+<a name="dbu"/><h2>"dbu" - Gets or sets the database unit to use</h2>
 <keyword name="dbu"/>
-<a name="dbu"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>dbu(dbu)</tt></li>
 <li><tt>dbu</tt></li>
@@ -257,9 +269,9 @@ for two layouts (i.e. take the largest common denominator).
 When the database unit is set, it must be set at the beginning
 of the script and before any operation that uses it.
 </p>
-<h2>"deep" - Enters deep (hierarchical) mode</h2>
+<a name="deep"/><h2>"deep" - Enters deep (hierarchical) mode</h2>
 <keyword name="deep"/>
-<a name="deep"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>deep</tt></li>
 </ul>
@@ -277,28 +289,31 @@ implied always. Sometimes cell variants will be created.
 </p><p>
 Deep mode can be cancelled with <a href="#tiles">tiles</a> or <a href="#flat">flat</a>.
 </p>
-<h2>"device_scaling" - Specifies a dimension scale factor for the geometrical device properties</h2>
+<a name="device_scaling"/><h2>"device_scaling" - Specifies a dimension scale factor for the geometrical device properties</h2>
 <keyword name="device_scaling"/>
-<a name="device_scaling"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>device_scaling(factor)</tt></li>
 </ul>
 <p>
 See <a href="/about/drc_ref_netter.xml#device_scaling">Netter#device_scaling</a> for a description of that function.
 </p>
-<h2>"diode" - Supplies the diode extractor class</h2>
+<a name="diode"/><h2>"diode" - Supplies the diode extractor class</h2>
 <keyword name="diode"/>
-<a name="diode"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>diode(name)</tt></li>
 </ul>
 <p>
 Use this class with <a href="#extract_devices">extract_devices</a> to specify extraction of a 
 planar diode 
+</p><p>
+See <class_doc href="DeviceExtractorDiode">DeviceExtractorDiode</class_doc> for more details
+about this extractor.
 </p>
-<h2>"dmos3" - Supplies the DMOS3 transistor extractor class</h2>
+<a name="dmos3"/><h2>"dmos3" - Supplies the DMOS3 transistor extractor class</h2>
 <keyword name="dmos3"/>
-<a name="dmos3"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>dmos3(name)</tt></li>
 </ul>
@@ -307,10 +322,13 @@ Use this class with <a href="#extract_devices">extract_devices</a> to specify ex
 three-terminal DMOS transistor. A DMOS transistor is essentially
 the same than a MOS transistor, but source and drain are 
 separated.
+</p><p>
+See <class_doc href="DeviceExtractorMOS3Transistor">DeviceExtractorMOS3Transistor</class_doc> for more details
+about this extractor (strict mode applies for 'dmos3').
 </p>
-<h2>"dmos4" - Supplies the MOS4 transistor extractor class</h2>
+<a name="dmos4"/><h2>"dmos4" - Supplies the MOS4 transistor extractor class</h2>
 <keyword name="dmos4"/>
-<a name="dmos4"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>dmos4(name)</tt></li>
 </ul>
@@ -319,10 +337,13 @@ Use this class with <a href="#extract_devices">extract_devices</a> to specify ex
 four-terminal DMOS transistor. A DMOS transistor is essentially
 the same than a MOS transistor, but source and drain are 
 separated.
+</p><p>
+See <class_doc href="DeviceExtractorMOS4Transistor">DeviceExtractorMOS4Transistor</class_doc> for more details
+about this extractor (strict mode applies for 'dmos4').
 </p>
-<h2>"edge" - Creates an edge object</h2>
+<a name="edge"/><h2>"edge" - Creates an edge object</h2>
 <keyword name="edge"/>
-<a name="edge"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>edge(...)</tt></li>
 </ul>
@@ -330,9 +351,9 @@ separated.
 This function creates an edge object. The arguments are the same than for the 
 <class_doc href="DEdge">DEdge</class_doc> constructors.
 </p>
-<h2>"edge_layer" - Creates an empty edge layer</h2>
+<a name="edge_layer"/><h2>"edge_layer" - Creates an empty edge layer</h2>
 <keyword name="edge_layer"/>
-<a name="edge_layer"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>edge_layer</tt></li>
 </ul>
@@ -340,27 +361,27 @@ This function creates an edge object. The arguments are the same than for the
 The intention of that method is to create an empty layer which can be 
 filled with edge objects using <a href="/about/drc_ref_layer.xml#insert">Layer#insert</a>.
 </p>
-<h2>"error" - Prints an error</h2>
+<a name="error"/><h2>"error" - Prints an error</h2>
 <keyword name="error"/>
-<a name="error"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>error(message)</tt></li>
 </ul>
 <p>
 Similar to <a href="#log">log</a>, but the message is printed formatted as an error
 </p>
-<h2>"extent" - Creates a new layer with the bounding box of the default source</h2>
+<a name="extent"/><h2>"extent" - Creates a new layer with the bounding box of the default source</h2>
 <keyword name="extent"/>
-<a name="extent"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>extent</tt></li>
 </ul>
 <p>
 See <a href="/about/drc_ref_source.xml#extent">Source#extent</a> for a description of that function.
 </p>
-<h2>"extract_devices" - Extracts devices for a given device extractor and device layer selection</h2>
+<a name="extract_devices"/><h2>"extract_devices" - Extracts devices for a given device extractor and device layer selection</h2>
 <keyword name="extract_devices"/>
-<a name="extract_devices"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>extract_devices(extractor, layer_hash)</tt></li>
 <li><tt>extract_devices(extractor_class, name, layer_hash)</tt></li>
@@ -368,18 +389,18 @@ See <a href="/about/drc_ref_source.xml#extent">Source#extent</a> for a descripti
 <p>
 See <a href="/about/drc_ref_netter.xml#extract_devices">Netter#extract_devices</a> for a description of that function.
 </p>
-<h2>"flat" - Disables tiling mode</h2>
+<a name="flat"/><h2>"flat" - Disables tiling mode</h2>
 <keyword name="flat"/>
-<a name="flat"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>flat</tt></li>
 </ul>
 <p>
 Disables tiling mode. Tiling mode can be enabled again with <a href="#tiles">tiles</a> later.
 </p>
-<h2>"info" - Outputs as message to the logger window</h2>
+<a name="info"/><h2>"info" - Outputs as message to the logger window</h2>
 <keyword name="info"/>
-<a name="info"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>info(message)</tt></li>
 </ul>
@@ -388,9 +409,9 @@ Prints the message to the log window in verbose mode.
 In non-verbose more, nothing is printed.
 <a href="#log">log</a> is a function that always prints a message.
 </p>
-<h2>"input" - Fetches the shapes from the specified input from the default source</h2>
+<a name="input"/><h2>"input" - Fetches the shapes from the specified input from the default source</h2>
 <keyword name="input"/>
-<a name="input"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>input(args)</tt></li>
 </ul>
@@ -399,48 +420,48 @@ See <a href="/about/drc_ref_source.xml#input">Source#input</a> for a description
 polygons and labels. See <a href="#polygons">polygons</a> and <a href="#labels">labels</a> for more specific versions of
 this method.
 </p>
-<h2>"is_deep?" - Returns true, if in deep mode</h2>
+<a name="is_deep?"/><h2>"is_deep?" - Returns true, if in deep mode</h2>
 <keyword name="is_deep?"/>
-<a name="is_deep?"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>is_deep?</tt></li>
 </ul>
-<h2>"is_tiled?" - Returns true, if in tiled mode</h2>
+<a name="is_tiled?"/><h2>"is_tiled?" - Returns true, if in tiled mode</h2>
 <keyword name="is_tiled?"/>
-<a name="is_tiled?"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>is_tiled?</tt></li>
 </ul>
-<h2>"l2n_data" - Gets the internal <class_doc href="LayoutToNetlist">LayoutToNetlist</class_doc> object for the default <a href="#Netter">Netter</a></h2>
+<a name="l2n_data"/><h2>"l2n_data" - Gets the internal <class_doc href="LayoutToNetlist">LayoutToNetlist</class_doc> object for the default <a href="#Netter">Netter</a></h2>
 <keyword name="l2n_data"/>
-<a name="l2n_data"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>l2n_data</tt></li>
 </ul>
 <p>
 See <a href="/about/drc_ref_netter.xml#l2n_data">Netter#l2n_data</a> for a description of that function.
 </p>
-<h2>"labels" - Gets the labels (text) from an original layer</h2>
+<a name="labels"/><h2>"labels" - Gets the labels (text) from an original layer</h2>
 <keyword name="labels"/>
-<a name="labels"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>labels</tt></li>
 </ul>
 <p>
 See <a href="/about/drc_ref_source.xml#labels">Source#labels</a> for a description of that function.
 </p>
-<h2>"layers" - Gets the layers contained in the default source</h2>
+<a name="layers"/><h2>"layers" - Gets the layers contained in the default source</h2>
 <keyword name="layers"/>
-<a name="layers"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layers</tt></li>
 </ul>
 <p>
 See <a href="/about/drc_ref_source.xml#layers">Source#layers</a> for a description of that function.
 </p>
-<h2>"layout" - Specifies an additional layout for the input source.</h2>
+<a name="layout"/><h2>"layout" - Specifies an additional layout for the input source.</h2>
 <keyword name="layout"/>
-<a name="layout"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layout</tt></li>
 <li><tt>layout(what)</tt></li>
@@ -475,9 +496,9 @@ l2 = layout("second_layout.gds")
 </p><p>
 For further methods on the source object see <a href="#Source">Source</a>.
 </p>
-<h2>"log" - Outputs as message to the logger window</h2>
+<a name="log"/><h2>"log" - Outputs as message to the logger window</h2>
 <keyword name="log"/>
-<a name="log"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>log(message)</tt></li>
 </ul>
@@ -486,9 +507,9 @@ Prints the message to the log window.
 <a href="#info">info</a> is a function that prints a message only if 
 verbose mode is enabled.
 </p>
-<h2>"log_file" - Specify the log file where to send to log to</h2>
+<a name="log_file"/><h2>"log_file" - Specify the log file where to send to log to</h2>
 <keyword name="log_file"/>
-<a name="log_file"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>log_file(filename)</tt></li>
 </ul>
@@ -496,9 +517,9 @@ verbose mode is enabled.
 After using that method, the log output is sent to the 
 given file instead of the logger window or the terminal.
 </p>
-<h2>"make_layer" - Creates an empty polygon layer based on the hierarchical scheme selected</h2>
+<a name="make_layer"/><h2>"make_layer" - Creates an empty polygon layer based on the hierarchical scheme selected</h2>
 <keyword name="make_layer"/>
-<a name="make_layer"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>make_layer</tt></li>
 </ul>
@@ -514,63 +535,69 @@ delivered by <a href="#polygon_layer">polygon_layer</a> is not.
 On the other hand, a layer created by the <a href="#make_layer">make_layer</a> method is not intended to be
 filled with <a href="/about/drc_ref_layer.xml#insert">Layer#insert</a>.
 </p>
-<h2>"mos3" - Supplies the MOS3 transistor extractor class</h2>
+<a name="mos3"/><h2>"mos3" - Supplies the MOS3 transistor extractor class</h2>
 <keyword name="mos3"/>
-<a name="mos3"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>mos3(name)</tt></li>
 </ul>
 <p>
 Use this class with <a href="#extract_devices">extract_devices</a> to specify extraction of a 
-three-terminal MOS transistor
+three-terminal MOS transistor.
+</p><p>
+See <class_doc href="DeviceExtractorMOS3Transistor">DeviceExtractorMOS3Transistor</class_doc> for more details
+about this extractor (non-strict mode applies for 'mos3').
 </p>
-<h2>"mos4" - Supplies the MOS4 transistor extractor class</h2>
+<a name="mos4"/><h2>"mos4" - Supplies the MOS4 transistor extractor class</h2>
 <keyword name="mos4"/>
-<a name="mos4"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>mos4(name)</tt></li>
 </ul>
 <p>
 Use this class with <a href="#extract_devices">extract_devices</a> to specify extraction of a 
-four-terminal MOS transistor
+four-terminal MOS transistor.
+</p><p>
+See <class_doc href="DeviceExtractorMOS4Transistor">DeviceExtractorMOS4Transistor</class_doc> for more details
+about this extractor (non-strict mode applies for 'mos4').
 </p>
-<h2>"netlist" - Obtains the extracted netlist from the default <a href="#Netter">Netter</a></h2>
+<a name="netlist"/><h2>"netlist" - Obtains the extracted netlist from the default <a href="#Netter">Netter</a></h2>
 <keyword name="netlist"/>
-<a name="netlist"/><p>
+<p>
 The netlist is a <class_doc href="Netlist">Netlist</class_doc> object. If no netlist is extracted 
 yet, this method will trigger the extraction process.
 See <a href="/about/drc_ref_netter.xml#netlist">Netter#netlist</a> for a description of this function.
 </p>
-<h2>"netter" - Creates a new netter object</h2>
+<a name="netter"/><h2>"netter" - Creates a new netter object</h2>
 <keyword name="netter"/>
-<a name="netter"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>netter</tt></li>
 </ul>
 <p>
 See <a href="/about/drc_ref_netter.xml">Netter</a> for more details
 </p>
-<h2>"no_borders" - Reset the tile borders</h2>
+<a name="no_borders"/><h2>"no_borders" - Reset the tile borders</h2>
 <keyword name="no_borders"/>
-<a name="no_borders"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>no_borders</tt></li>
 </ul>
 <p>
 Resets the tile borders - see <a href="#tile_borders">tile_borders</a> for a description of tile borders.
 </p>
-<h2>"output" - Outputs a layer to the report database or output layout</h2>
+<a name="output"/><h2>"output" - Outputs a layer to the report database or output layout</h2>
 <keyword name="output"/>
-<a name="output"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>output(layer, args)</tt></li>
 </ul>
 <p>
 This function is equivalent to "layer.output(args)". See <a href="/about/drc_ref_layer.xml#output">Layer#output</a> for details about this function.
 </p>
-<h2>"output_cell" - Specifies a target cell, but does not change the target layout</h2>
+<a name="output_cell"/><h2>"output_cell" - Specifies a target cell, but does not change the target layout</h2>
 <keyword name="output_cell"/>
-<a name="output_cell"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>output_cell(cellname)</tt></li>
 </ul>
@@ -579,9 +606,9 @@ This method switches output to the specified cell, but does not
 change the target layout nor does it switch the output channel to
 layout if is report database. 
 </p>
-<h2>"p" - Creates a point object</h2>
+<a name="p"/><h2>"p" - Creates a point object</h2>
 <keyword name="p"/>
-<a name="p"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>p(x, y)</tt></li>
 </ul>
@@ -594,9 +621,9 @@ x = polygon_layer
 x.insert(polygon([ p(0, 0), p(16.0, 0), p(8.0, 8.0) ]))
 </pre>
 </p>
-<h2>"path" - Creates a path object</h2>
+<a name="path"/><h2>"path" - Creates a path object</h2>
 <keyword name="path"/>
-<a name="path"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>path(...)</tt></li>
 </ul>
@@ -604,9 +631,9 @@ x.insert(polygon([ p(0, 0), p(16.0, 0), p(8.0, 8.0) ]))
 This function creates a path object. The arguments are the same than for the 
 <class_doc href="DPath">DPath</class_doc> constructors.
 </p>
-<h2>"polygon" - Creates a polygon object</h2>
+<a name="polygon"/><h2>"polygon" - Creates a polygon object</h2>
 <keyword name="polygon"/>
-<a name="polygon"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>polygon(...)</tt></li>
 </ul>
@@ -614,9 +641,9 @@ This function creates a path object. The arguments are the same than for the
 This function creates a polygon object. The arguments are the same than for the 
 <class_doc href="DPolygon">DPolygon</class_doc> constructors.
 </p>
-<h2>"polygon_layer" - Creates an empty polygon layer</h2>
+<a name="polygon_layer"/><h2>"polygon_layer" - Creates an empty polygon layer</h2>
 <keyword name="polygon_layer"/>
-<a name="polygon_layer"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>polygon_layer</tt></li>
 </ul>
@@ -626,18 +653,18 @@ filled with polygon-like objects using <a href="/about/drc_ref_layer.xml#insert"
 A similar method which creates a hierarchical layer in deep mode is 
 <a href="#make_layer">make_layer</a>. This other layer is better suited for use with device extraction.
 </p>
-<h2>"polygons" - Fetches the polygons (or shapes that can be converted to polygons) from the specified input from the default source</h2>
+<a name="polygons"/><h2>"polygons" - Fetches the polygons (or shapes that can be converted to polygons) from the specified input from the default source</h2>
 <keyword name="polygons"/>
-<a name="polygons"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>polygons(args)</tt></li>
 </ul>
 <p>
 See <a href="/about/drc_ref_source.xml#polygons">Source#polygons</a> for a description of that function.
 </p>
-<h2>"report" - Specifies a report database for output</h2>
+<a name="report"/><h2>"report" - Specifies a report database for output</h2>
 <keyword name="report"/>
-<a name="report"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>report(description [, filename [, cellname ] ])</tt></li>
 </ul>
@@ -658,9 +685,9 @@ By default this is the cell name of the default source. If there
 is no source layout you'll need to give the cell name in the 
 third parameter.
 </p>
-<h2>"report_netlist" - Specifies an extracted netlist report for output</h2>
+<a name="report_netlist"/><h2>"report_netlist" - Specifies an extracted netlist report for output</h2>
 <keyword name="report_netlist"/>
-<a name="report_netlist"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>report_netlist([ filename [, long ] ])</tt></li>
 </ul>
@@ -675,19 +702,24 @@ will also be written to the given file.
 If a file name is given and "long" is true, a verbose 
 version of the L2N DB format will be used.
 </p>
-<h2>"resistor" - Supplies the resistor extractor class</h2>
+<a name="resistor"/><h2>"resistor" - Supplies the resistor extractor class</h2>
 <keyword name="resistor"/>
-<a name="resistor"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>resistor(name, sheet_rho)</tt></li>
 </ul>
 <p>
 Use this class with <a href="#extract_devices">extract_devices</a> to specify extraction of a resistor.
-The sheet_rho value is the sheet resistance in ohms/square.
+</p><p>
+The sheet_rho value is the sheet resistance in ohms/square. It is used
+to compute the resistance from the geometry.
+</p><p>
+See <class_doc href="DeviceExtractorResistor">DeviceExtractorResistor</class_doc> for more details
+about this extractor.
 </p>
-<h2>"resistor_with_bulk" - Supplies the resistor extractor class that includes a bulk terminal</h2>
+<a name="resistor_with_bulk"/><h2>"resistor_with_bulk" - Supplies the resistor extractor class that includes a bulk terminal</h2>
 <keyword name="resistor_with_bulk"/>
-<a name="resistor_with_bulk"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>resistor_with_bulk(name, sheet_rho)</tt></li>
 </ul>
@@ -695,28 +727,31 @@ The sheet_rho value is the sheet resistance in ohms/square.
 Use this class with <a href="#extract_devices">extract_devices</a> to specify extraction of a resistor 
 with a bulk terminal.
 The sheet_rho value is the sheet resistance in ohms/square.
+</p><p>
+See <class_doc href="DeviceExtractorResistorWithBulk">DeviceExtractorResistorWithBulk</class_doc> for more details
+about this extractor.
 </p>
-<h2>"select" - Specifies cell filters on the default source</h2>
+<a name="select"/><h2>"select" - Specifies cell filters on the default source</h2>
 <keyword name="select"/>
-<a name="select"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>select(args)</tt></li>
 </ul>
 <p>
 See <a href="/about/drc_ref_source.xml#select">Source#select</a> for a description of that function.
 </p>
-<h2>"silent" - Resets verbose mode</h2>
+<a name="silent"/><h2>"silent" - Resets verbose mode</h2>
 <keyword name="silent"/>
-<a name="silent"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>silent</tt></li>
 </ul>
 <p>
 This function is equivalent to "verbose(false)" (see <a href="#verbose">verbose</a>)
 </p>
-<h2>"source" - Specifies a source layout</h2>
+<a name="source"/><h2>"source" - Specifies a source layout</h2>
 <keyword name="source"/>
-<a name="source"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>source</tt></li>
 <li><tt>source(what)</tt></li>
@@ -751,9 +786,9 @@ l2 = layout("second_layout.gds")
 </p><p>
 For further methods on the source object see <a href="#Source">Source</a>.
 </p>
-<h2>"target" - Specify the target layout</h2>
+<a name="target"/><h2>"target" - Specify the target layout</h2>
 <keyword name="target"/>
-<a name="target"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>target(what [, cellname])</tt></li>
 </ul>
@@ -778,9 +813,9 @@ Except if the argument is a <class_doc href="Cell">Cell</class_doc> object, a ce
 stating the cell name under which the results are saved. If no cellname is 
 specified, either the current cell or "TOP" is used.
 </p>
-<h2>"target_netlist" - With this statement, an extracted netlist is finally written to a file</h2>
+<a name="target_netlist"/><h2>"target_netlist" - With this statement, an extracted netlist is finally written to a file</h2>
 <keyword name="target_netlist"/>
-<a name="target_netlist"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>target_netlist(filename [, format [, comment ] ])</tt></li>
 </ul>
@@ -794,9 +829,9 @@ The format parameter specifies the writer to use. You can use nil
 to use the standard format or produce a SPICE writer with <a href="#write_spice">write_spice</a>.
 See <a href="#write_spice">write_spice</a> for more details.
 </p>
-<h2>"threads" - Specifies the number of CPU cores to use in tiling mode</h2>
+<a name="threads"/><h2>"threads" - Specifies the number of CPU cores to use in tiling mode</h2>
 <keyword name="threads"/>
-<a name="threads"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>threads(n)</tt></li>
 </ul>
@@ -805,9 +840,9 @@ If using threads, tiles are distributed on multiple CPU cores for
 parallelization. Still, all tiles must be processed before the 
 operation proceeds with the next statement.
 </p>
-<h2>"tile_borders" - Specifies a minimum tile border</h2>
+<a name="tile_borders"/><h2>"tile_borders" - Specifies a minimum tile border</h2>
 <keyword name="tile_borders"/>
-<a name="tile_borders"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>tile_border(b)</tt></li>
 <li><tt>tile_border(bx, by)</tt></li>
@@ -826,9 +861,9 @@ given range, although not necessarily all.
 </p><p>
 To reset the tile borders, use <a href="#no_borders">no_borders</a> or "tile_borders(nil)".
 </p>
-<h2>"tiles" - Specifies tiling</h2>
+<a name="tiles"/><h2>"tiles" - Specifies tiling</h2>
 <keyword name="tiles"/>
-<a name="tiles"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>tiles(t)</tt></li>
 <li><tt>tiles(w, h)</tt></li>
@@ -851,9 +886,9 @@ To disable tiling mode use <a href="#flat">flat</a> or <a href="#deep">deep</a>.
 </p><p>
 Tiling mode will disable deep mode (see <a href="#deep">deep</a>).
 </p>
-<h2>"verbose" - Sets or resets verbose mode</h2>
+<a name="verbose"/><h2>"verbose" - Sets or resets verbose mode</h2>
 <keyword name="verbose"/>
-<a name="verbose"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>verbose</tt></li>
 <li><tt>verbose(m)</tt></li>
@@ -861,18 +896,18 @@ Tiling mode will disable deep mode (see <a href="#deep">deep</a>).
 <p>
 In verbose mode, more output is generated in the log file
 </p>
-<h2>"verbose?" - Returns true, if verbose mode is enabled</h2>
+<a name="verbose?"/><h2>"verbose?" - Returns true, if verbose mode is enabled</h2>
 <keyword name="verbose?"/>
-<a name="verbose?"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>verbose?</tt></li>
 </ul>
 <p>
 In verbose mode, more output is generated in the log file
 </p>
-<h2>"write_spice" - Defines SPICE output format (with options)</h2>
+<a name="write_spice"/><h2>"write_spice" - Defines SPICE output format (with options)</h2>
 <keyword name="write_spice"/>
-<a name="write_spice"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>write_spice([ use_net_names [, with_comments ] ])</tt></li>
 </ul>
diff --git a/src/lay/lay/doc/about/drc_ref_layer.xml b/src/lay/lay/doc/about/drc_ref_layer.xml
index faa14fb73..d7287b733 100644
--- a/src/lay/lay/doc/about/drc_ref_layer.xml
+++ b/src/lay/lay/doc/about/drc_ref_layer.xml
@@ -11,9 +11,9 @@
 The layer object represents a collection of polygons, edges or edge pairs.
 </p>
 <h2-index/>
-<h2>"&amp;" - Boolean AND operation</h2>
+<a name="&amp;"/><h2>"&amp;" - Boolean AND operation</h2>
 <keyword name="&amp;"/>
-<a name="&amp;"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>self &amp; other</tt></li>
 </ul>
@@ -23,9 +23,9 @@ The method computes a boolean AND between self and other.
 This method is available for polygon and edge layers. An alias
 is "<a href="#and">and</a>". See there for a description of the function.
 </p>
-<h2>"+" - Join layers</h2>
+<a name="+"/><h2>"+" - Join layers</h2>
 <keyword name="+"/>
-<a name="+"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>self + other</tt></li>
 </ul>
@@ -36,9 +36,9 @@ The "+" operator is an alias for the <a href="#join">join</a> method.
 This method is available for polygon, edge and edge pair layers. An alias
 is "<a href="#join">join</a>". See there for a description of the function.
 </p>
-<h2>"-" - Boolean NOT operation</h2>
+<a name="-"/><h2>"-" - Boolean NOT operation</h2>
 <keyword name="-"/>
-<a name="-"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>self - other</tt></li>
 </ul>
@@ -48,9 +48,9 @@ The method computes a boolean NOT between self and other.
 This method is available for polygon and edge layers. An alias
 is "<a href="#not">not</a>". See there for a description of the function.
 </p>
-<h2>"^" - Boolean XOR operation</h2>
+<a name="^"/><h2>"^" - Boolean XOR operation</h2>
 <keyword name="^"/>
-<a name="^"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>self ^ other</tt></li>
 </ul>
@@ -60,9 +60,9 @@ The method computes a boolean XOR between self and other.
 This method is available for polygon and edge layers. An alias
 is "<a href="#xor">xor</a>". See there for a description of the function.
 </p>
-<h2>"and" - Boolean AND operation</h2>
+<a name="and"/><h2>"and" - Boolean AND operation</h2>
 <keyword name="and"/>
-<a name="and"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.and(other)</tt></li>
 </ul>
@@ -86,9 +86,9 @@ on polygons and edges (layer1: red, layer2: blue):
 </tr>
 </table>
 </p>
-<h2>"area" - Returns the total area of the polygons in the region</h2>
+<a name="area"/><h2>"area" - Returns the total area of the polygons in the region</h2>
 <keyword name="area"/>
-<a name="area"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.area</tt></li>
 </ul>
@@ -101,9 +101,9 @@ polygons are not counted twice.
 </p><p>
 The returned value gives the area in square micrometer units.
 </p>
-<h2>"bbox" - Returns the overall bounding box of the layer</h2>
+<a name="bbox"/><h2>"bbox" - Returns the overall bounding box of the layer</h2>
 <keyword name="bbox"/>
-<a name="bbox"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.bbox</tt></li>
 </ul>
@@ -111,9 +111,9 @@ The returned value gives the area in square micrometer units.
 The return value is a <class_doc href="DBox">DBox</class_doc> object giving the bounding box in 
 micrometer units. 
 </p>
-<h2>"centers" - Returns the center parts of the edges</h2>
+<a name="centers"/><h2>"centers" - Returns the center parts of the edges</h2>
 <keyword name="centers"/>
-<a name="centers"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.centers(length)</tt></li>
 <li><tt>layer.centers(length, fraction)</tt></li>
@@ -132,9 +132,9 @@ The following images show the effect of the method:
 </tr>
 </table>
 </p>
-<h2>"clean" - Marks a layer as clean</h2>
+<a name="clean"/><h2>"clean" - Marks a layer as clean</h2>
 <keyword name="clean"/>
-<a name="clean"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.clean</tt></li>
 </ul>
@@ -148,9 +148,9 @@ Clean state is the default.
 See <a href="#raw">raw</a> for some remarks about how this state is 
 propagated.
 </p>
-<h2>"collect" - Transforms a layer</h2>
+<a name="collect"/><h2>"collect" - Transforms a layer</h2>
 <keyword name="collect"/>
-<a name="collect"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.collect { |object| ... }</tt></li>
 </ul>
@@ -182,9 +182,9 @@ t = <class_doc href="DCplxTrans">DCplxTrans</class_doc>(1.0, 45.0, false, <class
 new_layer = layer.collect { |polygon| polygon.transformed(t) }
 </pre>
 </p>
-<h2>"collect_to_edge_pairs" - Transforms a layer into edge pair objects</h2>
+<a name="collect_to_edge_pairs"/><h2>"collect_to_edge_pairs" - Transforms a layer into edge pair objects</h2>
 <keyword name="collect_to_edge_pairs"/>
-<a name="collect_to_edge_pairs"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.collect { |object| ... }</tt></li>
 </ul>
@@ -192,9 +192,9 @@ new_layer = layer.collect { |polygon| polygon.transformed(t) }
 This method is similar to <a href="#collect">collect</a>, but creates an edge pair layer. It expects the block to 
 deliver <class_doc href="EdgePair">EdgePair</class_doc>, <class_doc href="DEdgePair">DEdgePair</class_doc> or <class_doc href="EdgePairs">EdgePairs</class_doc> objects.
 </p>
-<h2>"collect_to_edges" - Transforms a layer into edge objects</h2>
+<a name="collect_to_edges"/><h2>"collect_to_edges" - Transforms a layer into edge objects</h2>
 <keyword name="collect_to_edges"/>
-<a name="collect_to_edges"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.collect { |object| ... }</tt></li>
 </ul>
@@ -203,9 +203,9 @@ This method is similar to <a href="#collect">collect</a>, but creates an edge la
 deliver objects that can be converted into edges. If polygon-like objects are returned, their
 contours will be turned into edge sequences.
 </p>
-<h2>"collect_to_region" - Transforms a layer into polygon objects</h2>
+<a name="collect_to_region"/><h2>"collect_to_region" - Transforms a layer into polygon objects</h2>
 <keyword name="collect_to_region"/>
-<a name="collect_to_region"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.collect { |object| ... }</tt></li>
 </ul>
@@ -214,9 +214,9 @@ This method is similar to <a href="#collect">collect</a>, but creates a polygon
 deliver objects that can be converted into polygons. Such objects are of class <class_doc href="DPolygon">DPolygon</class_doc>,
 <class_doc href="DBox">DBox</class_doc>, <class_doc href="DPath">DPath</class_doc>, <class_doc href="Polygon">Polygon</class_doc>, <class_doc href="Path">Path</class_doc>, <class_doc href="Box">Box</class_doc> and <class_doc href="Region">Region</class_doc>.
 </p>
-<h2>"corners" - Selects corners of polygons</h2>
+<a name="corners"/><h2>"corners" - Selects corners of polygons</h2>
 <keyword name="corners"/>
-<a name="corners"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.corners([ options ])</tt></li>
 <li><tt>layer.corners(angle, [ options ])</tt></li>
@@ -247,9 +247,9 @@ The following images show the effect of this method:
 </tr>
 </table>
 </p>
-<h2>"data" - Gets the low-level data object</h2>
+<a name="data"/><h2>"data" - Gets the low-level data object</h2>
 <keyword name="data"/>
-<a name="data"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.data</tt></li>
 </ul>
@@ -259,9 +259,9 @@ representing the underlying RBA object for the data.
 Access to these objects is provided to support low-level iteration and manipulation
 of the layer's data. 
 </p>
-<h2>"dup" - Duplicates a layer</h2>
+<a name="dup"/><h2>"dup" - Duplicates a layer</h2>
 <keyword name="dup"/>
-<a name="dup"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.dup</tt></li>
 </ul>
@@ -276,9 +276,9 @@ layer. Using the dup method will avoid that.
 However, dup will double the memory required to hold the data 
 and performing the deep copy may be expensive in terms of CPU time.
 </p>
-<h2>"each" - Iterates over the objects from the layer</h2>
+<a name="each"/><h2>"each" - Iterates over the objects from the layer</h2>
 <keyword name="each"/>
-<a name="each"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.each { |object| ... }</tt></li>
 </ul>
@@ -289,15 +289,15 @@ layer type, these objects are of <class_doc href="DPolygon">DPolygon</class_doc>
 Because this method executes inside the interpreter, it's inherently slow. Tiling does not
 apply to this method.
 </p>
-<h2>"edge_pairs?" - Returns true, if the layer is an edge pair collection</h2>
+<a name="edge_pairs?"/><h2>"edge_pairs?" - Returns true, if the layer is an edge pair collection</h2>
 <keyword name="edge_pairs?"/>
-<a name="edge_pairs?"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.edge_pairs?</tt></li>
 </ul>
-<h2>"edges" - Decomposes the layer into single edges</h2>
+<a name="edges"/><h2>"edges" - Decomposes the layer into single edges</h2>
 <keyword name="edges"/>
-<a name="edges"/><p>
+<p>
 Edge pair collections are decomposed into the individual edges that make up
 the edge pairs. Polygon layers are decomposed into the edges making up the 
 polygons. This method returns an edge layer but will not modify the layer it 
@@ -306,24 +306,24 @@ is called on.
 Merged semantics applies, i.e. the result reflects merged polygons rather than
 individual ones unless raw mode is chosen.
 </p>
-<h2>"edges?" - Returns true, if the layer is an edge layer</h2>
+<a name="edges?"/><h2>"edges?" - Returns true, if the layer is an edge layer</h2>
 <keyword name="edges?"/>
-<a name="edges?"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.edges?</tt></li>
 </ul>
-<h2>"enc" - An alias for "enclosing"</h2>
+<a name="enc"/><h2>"enc" - An alias for "enclosing"</h2>
 <keyword name="enc"/>
-<a name="enc"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.enc(value [, options])</tt></li>
 </ul>
 <p>
 See <a href="#enclosing">enclosing</a> for a description of that method
 </p>
-<h2>"enclosing" - An enclosing check</h2>
+<a name="enclosing"/><h2>"enclosing" - An enclosing check</h2>
 <keyword name="enclosing"/>
-<a name="enclosing"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.enclosing(other_layer, value [, options])</tt></li>
 </ul>
@@ -354,9 +354,9 @@ The following images show the effect of two enclosing checks (red: input1, blue:
 </tr>
 </table>
 </p>
-<h2>"end_segments" - Returns the part at the end of each edge</h2>
+<a name="end_segments"/><h2>"end_segments" - Returns the part at the end of each edge</h2>
 <keyword name="end_segments"/>
-<a name="end_segments"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.end_segments(length)</tt></li>
 <li><tt>layer.end_segments(length, fraction)</tt></li>
@@ -388,9 +388,9 @@ The following images show the effect of the method:
 </tr>
 </table>
 </p>
-<h2>"extended" - Returns polygons describing an area along the edges of the input</h2>
+<a name="extended"/><h2>"extended" - Returns polygons describing an area along the edges of the input</h2>
 <keyword name="extended"/>
-<a name="extended"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.extended([:begin =&gt; b,] [:end =&gt; e,] [:out =&gt; o,] [:in =&gt; i], [:joined =&gt; true])</tt></li>
 <li><tt>layer.extended(b, e, o, i)</tt></li>
@@ -423,9 +423,9 @@ The following images show the effects of some parameters:
 </tr>
 </table>
 </p>
-<h2>"extended_in" - Returns polygons describing an area along the edges of the input</h2>
+<a name="extended_in"/><h2>"extended_in" - Returns polygons describing an area along the edges of the input</h2>
 <keyword name="extended_in"/>
-<a name="extended_in"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.extended_in(d)</tt></li>
 </ul>
@@ -437,9 +437,9 @@ This method is basically equivalent to the <a href="#extended">extended</a> meth
 "extended(0, 0, 0, dist)".
 A version extending to the outside is <a href="#extended_out">extended_out</a>.
 </p>
-<h2>"extended_out" - Returns polygons describing an area along the edges of the input</h2>
+<a name="extended_out"/><h2>"extended_out" - Returns polygons describing an area along the edges of the input</h2>
 <keyword name="extended_out"/>
-<a name="extended_out"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.extended_out(d)</tt></li>
 </ul>
@@ -451,9 +451,9 @@ This method is basically equivalent to the <a href="#extended">extended</a> meth
 "extended(0, 0, dist, 0)".
 A version extending to the inside is <a href="#extended_in">extended_in</a>.
 </p>
-<h2>"extent_refs" - Returns partial references to the boundings boxes of the polygons</h2>
+<a name="extent_refs"/><h2>"extent_refs" - Returns partial references to the boundings boxes of the polygons</h2>
 <keyword name="extent_refs"/>
-<a name="extent_refs"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.extent_refs(fx, fy [, options ])</tt></li>
 <li><tt>layer.extent_refs(fx1, fy1, fx2, fx2 [, options ])</tt></li>
@@ -547,9 +547,9 @@ The following table shows a few applications:
 </tr>
 </table>
 </p>
-<h2>"extents" - Returns the bounding box of each input object</h2>
+<a name="extents"/><h2>"extents" - Returns the bounding box of each input object</h2>
 <keyword name="extents"/>
-<a name="extents"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.extents([ enlargement ])</tt></li>
 </ul>
@@ -574,9 +574,9 @@ The following images show the effect of the extents method:
 </tr>
 </table>
 </p>
-<h2>"first_edges" - Returns the first edges of an edge pair collection</h2>
+<a name="first_edges"/><h2>"first_edges" - Returns the first edges of an edge pair collection</h2>
 <keyword name="first_edges"/>
-<a name="first_edges"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.first_edges</tt></li>
 </ul>
@@ -584,9 +584,9 @@ The following images show the effect of the extents method:
 Applies to edge pair collections only.
 Returns the first edges of the edge pairs in the collection.
 </p>
-<h2>"flatten" - Flattens the layer</h2>
+<a name="flatten"/><h2>"flatten" - Flattens the layer</h2>
 <keyword name="flatten"/>
-<a name="flatten"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.flatten</tt></li>
 </ul>
@@ -596,9 +596,9 @@ If the layer is a hierarchical layer (an original layer or
 a derived layer in deep mode), this method will convert it
 to a flat collection of polygons, edges or edge pairs.
 </p>
-<h2>"holes" - Selects all polygon holes from the input</h2>
+<a name="holes"/><h2>"holes" - Selects all polygon holes from the input</h2>
 <keyword name="holes"/>
-<a name="holes"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.holes</tt></li>
 </ul>
@@ -616,9 +616,9 @@ The following image shows the effects of the holes method:
 </tr>
 </table>
 </p>
-<h2>"hulls" - Selects all polygon hulls from the input</h2>
+<a name="hulls"/><h2>"hulls" - Selects all polygon hulls from the input</h2>
 <keyword name="hulls"/>
-<a name="hulls"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.hulls</tt></li>
 </ul>
@@ -636,9 +636,9 @@ The following image shows the effects of the hulls method:
 </tr>
 </table>
 </p>
-<h2>"in" - Selects shapes or regions of self which are contained in the other layer</h2>
+<a name="in"/><h2>"in" - Selects shapes or regions of self which are contained in the other layer</h2>
 <keyword name="in"/>
-<a name="in"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.in(other)</tt></li>
 </ul>
@@ -661,9 +661,9 @@ The following image shows the effect of the "in" method (input1: red, input2: bl
 </tr>
 </table>
 </p>
-<h2>"insert" - Inserts one or many objects into the layer</h2>
+<a name="insert"/><h2>"insert" - Inserts one or many objects into the layer</h2>
 <keyword name="insert"/>
-<a name="insert"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>insert(object, object ...)</tt></li>
 </ul>
@@ -683,9 +683,9 @@ pl = polygon_layer
 pl.insert(box(0.0, 0.0, 100.0, 200.0)
 </pre>
 </p>
-<h2>"inside" - Selects shapes or regions of self which are inside the other region</h2>
+<a name="inside"/><h2>"inside" - Selects shapes or regions of self which are inside the other region</h2>
 <keyword name="inside"/>
-<a name="inside"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.inside(other)</tt></li>
 </ul>
@@ -708,9 +708,9 @@ The following image shows the effect of the "inside" method (input1: red, input2
 </tr>
 </table>
 </p>
-<h2>"inside_part" - Returns the parts of the edges inside the given region</h2>
+<a name="inside_part"/><h2>"inside_part" - Returns the parts of the edges inside the given region</h2>
 <keyword name="inside_part"/>
-<a name="inside_part"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.inside_part(region)</tt></li>
 </ul>
@@ -727,9 +727,9 @@ This method is available for edge layers. The argument must be a polygon layer.
 </tr>
 </table>
 </p>
-<h2>"interacting" - Selects shapes or regions of self which touch or overlap shapes from the other region</h2>
+<a name="interacting"/><h2>"interacting" - Selects shapes or regions of self which touch or overlap shapes from the other region</h2>
 <keyword name="interacting"/>
-<a name="interacting"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.interacting(other)</tt></li>
 </ul>
@@ -751,9 +751,9 @@ The following image shows the effect of the "interacting" method (input1: red, i
 </tr>
 </table>
 </p>
-<h2>"intersections" - Returns the intersection points of intersecting edge segments for two edge collections</h2>
+<a name="intersections"/><h2>"intersections" - Returns the intersection points of intersecting edge segments for two edge collections</h2>
 <keyword name="intersections"/>
-<a name="intersections"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.intersections(edges)</tt></li>
 </ul>
@@ -764,9 +764,9 @@ degenerated edge objects.
 </p><p>
 This method is available for edge layers. The argument must be an edge layer.
 </p>
-<h2>"is_box?" - Returns true, if the region contains a single box</h2>
+<a name="is_box?"/><h2>"is_box?" - Returns true, if the region contains a single box</h2>
 <keyword name="is_box?"/>
-<a name="is_box?"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.is_box?</tt></li>
 </ul>
@@ -775,30 +775,30 @@ The method returns true, if the region consists of a single box
 only. Merged semantics does not apply - if the region forms a box which
 is composed of multiple pieces, this method will not return true.
 </p>
-<h2>"is_clean?" - Returns true, if the layer is clean state</h2>
+<a name="is_clean?"/><h2>"is_clean?" - Returns true, if the layer is clean state</h2>
 <keyword name="is_clean?"/>
-<a name="is_clean?"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.is_clean?</tt></li>
 </ul>
 <p>
 See <a href="#clean">clean</a> for a discussion of the clean state.
 </p>
-<h2>"is_deep?" - Returns true, if the layer is a deep (hierarchical) layer</h2>
+<a name="is_deep?"/><h2>"is_deep?" - Returns true, if the layer is a deep (hierarchical) layer</h2>
 <keyword name="is_deep?"/>
-<a name="is_deep?"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.is_deep?</tt></li>
 </ul>
-<h2>"is_empty?" - Returns true, if the layer is empty</h2>
+<a name="is_empty?"/><h2>"is_empty?" - Returns true, if the layer is empty</h2>
 <keyword name="is_empty?"/>
-<a name="is_empty?"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.is_empty?</tt></li>
 </ul>
-<h2>"is_merged?" - Returns true, if the polygons of the layer are merged</h2>
+<a name="is_merged?"/><h2>"is_merged?" - Returns true, if the polygons of the layer are merged</h2>
 <keyword name="is_merged?"/>
-<a name="is_merged?"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.is_merged?</tt></li>
 </ul>
@@ -809,27 +809,27 @@ In clean mode, this is ensured implicitly. In raw mode (see <a href="#raw">raw</
 merging can be achieved by using the <a href="#merge">merge</a> method. <a href="#is_merged">is_merged</a>?
 tells, whether calling <a href="#merge">merge</a> is necessary.
 </p>
-<h2>"is_raw?" - Returns true, if the layer is raw state</h2>
+<a name="is_raw?"/><h2>"is_raw?" - Returns true, if the layer is raw state</h2>
 <keyword name="is_raw?"/>
-<a name="is_raw?"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.is_raw?</tt></li>
 </ul>
 <p>
 See <a href="#clean">clean</a> for a discussion of the raw state.
 </p>
-<h2>"iso" - An alias for "isolated"</h2>
+<a name="iso"/><h2>"iso" - An alias for "isolated"</h2>
 <keyword name="iso"/>
-<a name="iso"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.iso(value [, options])</tt></li>
 </ul>
 <p>
 See <a href="#isolated">isolated</a> for a description of that method
 </p>
-<h2>"isolated" - An isolation check</h2>
+<a name="isolated"/><h2>"isolated" - An isolation check</h2>
 <keyword name="isolated"/>
-<a name="isolated"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.isolated(value [, options])</tt></li>
 </ul>
@@ -847,9 +847,9 @@ The following image shows the effect of the isolated check:
 </tr>
 </table>
 </p>
-<h2>"join" - Joins the layer with another layer</h2>
+<a name="join"/><h2>"join" - Joins the layer with another layer</h2>
 <keyword name="join"/>
-<a name="join"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.join(other)</tt></li>
 </ul>
@@ -869,9 +869,9 @@ on polygons and edges (layer1: red, layer2: blue):
 </tr>
 </table>
 </p>
-<h2>"length" - Returns the total length of the edges in the edge layer</h2>
+<a name="length"/><h2>"length" - Returns the total length of the edges in the edge layer</h2>
 <keyword name="length"/>
-<a name="length"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.length</tt></li>
 </ul>
@@ -882,9 +882,9 @@ i.e. before computing the length, the edges are merged unless
 raw mode is chosen (see <a href="#raw">raw</a>). Hence in clean mode (see <a href="#clean">clean</a>), overlapping
 edges are not counted twice.
 </p>
-<h2>"merge" - Merges the layer (modifies the layer)</h2>
+<a name="merge"/><h2>"merge" - Merges the layer (modifies the layer)</h2>
 <keyword name="merge"/>
-<a name="merge"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.merge([overlap_count])</tt></li>
 </ul>
@@ -892,9 +892,9 @@ edges are not counted twice.
 Like <a href="#merged">merged</a>, but modifies the input and returns a reference to the 
 new layer.
 </p>
-<h2>"merged" - Returns the merged layer</h2>
+<a name="merged"/><h2>"merged" - Returns the merged layer</h2>
 <keyword name="merged"/>
-<a name="merged"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.merged([overlap_count])</tt></li>
 </ul>
@@ -923,9 +923,9 @@ The following images show the effect of various forms of the "merged" method:
 </tr>
 </table>
 </p>
-<h2>"middle" - Returns the center points of the bounding boxes of the polygons</h2>
+<a name="middle"/><h2>"middle" - Returns the center points of the bounding boxes of the polygons</h2>
 <keyword name="middle"/>
-<a name="middle"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.middle([ options ])</tt></li>
 </ul>
@@ -949,9 +949,9 @@ The following image shows the effect of this method
 </tr>
 </table>
 </p>
-<h2>"move" - Moves (shifts, translates) a layer (modifies the layer)</h2>
+<a name="move"/><h2>"move" - Moves (shifts, translates) a layer (modifies the layer)</h2>
 <keyword name="move"/>
-<a name="move"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.move(dx, dy)</tt></li>
 </ul>
@@ -962,9 +962,9 @@ upon is modified and the modified version is returned for further processing.
 Shift distances can be given as floating-point values (in micron) or integer values (in
 database units). To explicitly specify the unit, use the unit denominators.
 </p>
-<h2>"moved" - Moves (shifts, translates) a layer</h2>
+<a name="moved"/><h2>"moved" - Moves (shifts, translates) a layer</h2>
 <keyword name="moved"/>
-<a name="moved"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.moved(dx, dy)</tt></li>
 </ul>
@@ -983,9 +983,9 @@ The following images shows the effect of the "moved" method:
 </tr>
 </table>
 </p>
-<h2>"non_rectangles" - Selects all polygons from the input which are not rectangles</h2>
+<a name="non_rectangles"/><h2>"non_rectangles" - Selects all polygons from the input which are not rectangles</h2>
 <keyword name="non_rectangles"/>
-<a name="non_rectangles"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.non_rectangles</tt></li>
 </ul>
@@ -993,9 +993,9 @@ The following images shows the effect of the "moved" method:
 This method is available for polygon layers. By default "merged" semantics applies, 
 i.e. all polygons are merged before non-rectangles are selected (see <a href="#clean">clean</a> and <a href="#raw">raw</a>).
 </p>
-<h2>"non_rectilinear" - Selects all non-rectilinear polygons from the input</h2>
+<a name="non_rectilinear"/><h2>"non_rectilinear" - Selects all non-rectilinear polygons from the input</h2>
 <keyword name="non_rectilinear"/>
-<a name="non_rectilinear"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.non_rectilinear</tt></li>
 </ul>
@@ -1003,9 +1003,9 @@ i.e. all polygons are merged before non-rectangles are selected (see <a href="#c
 This method is available for polygon layers. By default "merged" semantics applies, 
 i.e. all polygons are merged before non-rectilinear polygons are selected (see <a href="#clean">clean</a> and <a href="#raw">raw</a>).
 </p>
-<h2>"non_strict" - Marks a layer for non-strict handling</h2>
+<a name="non_strict"/><h2>"non_strict" - Marks a layer for non-strict handling</h2>
 <keyword name="non_strict"/>
-<a name="non_strict"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.non_strict</tt></li>
 </ul>
@@ -1014,9 +1014,9 @@ See <a href="#strict">strict</a> for details about this option.
 </p><p>
 This feature has been introduced in version 0.23.2.
 </p>
-<h2>"not" - Boolean NOT operation</h2>
+<a name="not"/><h2>"not" - Boolean NOT operation</h2>
 <keyword name="not"/>
-<a name="not"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.not(other)</tt></li>
 </ul>
@@ -1040,9 +1040,9 @@ on polygons and edges (layer1: red, layer2: blue):
 </tr>
 </table>
 </p>
-<h2>"not_in" - Selects shapes or regions of self which are not contained in the other layer</h2>
+<a name="not_in"/><h2>"not_in" - Selects shapes or regions of self which are not contained in the other layer</h2>
 <keyword name="not_in"/>
-<a name="not_in"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.not_in(other)</tt></li>
 </ul>
@@ -1065,9 +1065,9 @@ The following image shows the effect of the "not_in" method (input1: red, input2
 </tr>
 </table>
 </p>
-<h2>"not_inside" - Selects shapes or regions of self which are not inside the other region</h2>
+<a name="not_inside"/><h2>"not_inside" - Selects shapes or regions of self which are not inside the other region</h2>
 <keyword name="not_inside"/>
-<a name="not_inside"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.not_inside(other)</tt></li>
 </ul>
@@ -1090,9 +1090,9 @@ The following image shows the effect of the "not_inside" method (input1: red, in
 </tr>
 </table>
 </p>
-<h2>"not_interacting" - Selects shapes or regions of self which do not touch or overlap shapes from the other region</h2>
+<a name="not_interacting"/><h2>"not_interacting" - Selects shapes or regions of self which do not touch or overlap shapes from the other region</h2>
 <keyword name="not_interacting"/>
-<a name="not_interacting"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.not_interacting(other)</tt></li>
 </ul>
@@ -1114,9 +1114,9 @@ The following image shows the effect of the "not_interacting" method (input1: re
 </tr>
 </table>
 </p>
-<h2>"not_outside" - Selects shapes or regions of self which are not outside the other region</h2>
+<a name="not_outside"/><h2>"not_outside" - Selects shapes or regions of self which are not outside the other region</h2>
 <keyword name="not_outside"/>
-<a name="not_outside"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.not_outside(other)</tt></li>
 </ul>
@@ -1139,9 +1139,9 @@ The following image shows the effect of the "not_outside" method (input1: red, i
 </tr>
 </table>
 </p>
-<h2>"not_overlapping" - Selects shapes or regions of self which do not overlap shapes from the other region</h2>
+<a name="not_overlapping"/><h2>"not_overlapping" - Selects shapes or regions of self which do not overlap shapes from the other region</h2>
 <keyword name="not_overlapping"/>
-<a name="not_overlapping"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.not_overlapping(other)</tt></li>
 </ul>
@@ -1158,9 +1158,9 @@ with respect to other edges or polygons.
 It returns a new layer containing the selected shapes. A version which modifies self
 is <a href="#select_not_overlapping">select_not_overlapping</a>.
 </p>
-<h2>"notch" - An intra-region spacing check</h2>
+<a name="notch"/><h2>"notch" - An intra-region spacing check</h2>
 <keyword name="notch"/>
-<a name="notch"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.notch(value [, options])</tt></li>
 </ul>
@@ -1178,9 +1178,9 @@ The following image shows the effect of the notch check:
 </tr>
 </table>
 </p>
-<h2>"odd_polygons" - Checks for odd polygons (self-overlapping, non-orientable)</h2>
+<a name="odd_polygons"/><h2>"odd_polygons" - Checks for odd polygons (self-overlapping, non-orientable)</h2>
 <keyword name="odd_polygons"/>
-<a name="odd_polygons"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.odd_polygons</tt></li>
 </ul>
@@ -1188,9 +1188,9 @@ The following image shows the effect of the notch check:
 Returns the parts of the polygons which are not orientable (i.e. "8" configuration) or self-overlapping.
 Merged semantics does not apply for this method. Always the raw polygons are taken (see <a href="#raw">raw</a>).
 </p>
-<h2>"ongrid" - Checks for on-grid vertices</h2>
+<a name="ongrid"/><h2>"ongrid" - Checks for on-grid vertices</h2>
 <keyword name="ongrid"/>
-<a name="ongrid"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.ongrid(g)</tt></li>
 <li><tt>layer.ongrid(gx, gy)</tt></li>
@@ -1203,9 +1203,9 @@ When setting the grid to 0, no grid check is performed in that specific directio
 </p><p>
 This method requires a polygon layer. Merged semantics applies (see <a href="#raw">raw</a> and <a href="#clean">clean</a>).
 </p>
-<h2>"or" - Boolean OR operation</h2>
+<a name="or"/><h2>"or" - Boolean OR operation</h2>
 <keyword name="or"/>
-<a name="or"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.or(other)</tt></li>
 </ul>
@@ -1225,9 +1225,9 @@ on polygons and edges (layer1: red, layer2: blue):
 </tr>
 </table>
 </p>
-<h2>"output" - Outputs the content of the layer</h2>
+<a name="output"/><h2>"output" - Outputs the content of the layer</h2>
 <keyword name="output"/>
-<a name="output"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.output(specs)</tt></li>
 </ul>
@@ -1245,9 +1245,9 @@ a single <class_doc href="LayerInfo">LayerInfo</class_doc> object.
 See <a href="/about/drc_ref_global.xml#report">global#report</a> and <a href="/about/drc_ref_global.xml#target">global#target</a> on how to configure output to a target layout
 or report database. 
 </p>
-<h2>"outside" - Selects shapes or regions of self which are outside the other region</h2>
+<a name="outside"/><h2>"outside" - Selects shapes or regions of self which are outside the other region</h2>
 <keyword name="outside"/>
-<a name="outside"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.outside(other)</tt></li>
 </ul>
@@ -1270,9 +1270,9 @@ The following image shows the effect of the "outside" method (input1: red, input
 </tr>
 </table>
 </p>
-<h2>"outside_part" - Returns the parts of the edges outside the given region</h2>
+<a name="outside_part"/><h2>"outside_part" - Returns the parts of the edges outside the given region</h2>
 <keyword name="outside_part"/>
-<a name="outside_part"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.outside_part(region)</tt></li>
 </ul>
@@ -1289,9 +1289,9 @@ This method is available for edge layers. The argument must be a polygon layer.
 </tr>
 </table>
 </p>
-<h2>"overlap" - An overlap check</h2>
+<a name="overlap"/><h2>"overlap" - An overlap check</h2>
 <keyword name="overlap"/>
-<a name="overlap"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.overlap(other_layer, value [, options])</tt></li>
 </ul>
@@ -1327,9 +1327,9 @@ The following images show the effect of the overlap check (layer1: red, layer2:
 </tr>
 </table>
 </p>
-<h2>"overlapping" - Selects shapes or regions of self which overlap shapes from the other region</h2>
+<a name="overlapping"/><h2>"overlapping" - Selects shapes or regions of self which overlap shapes from the other region</h2>
 <keyword name="overlapping"/>
-<a name="overlapping"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.overlapping(other)</tt></li>
 </ul>
@@ -1351,9 +1351,9 @@ The following image shows the effect of the "overlapping" method:
 </tr>
 </table>
 </p>
-<h2>"perimeter" - Returns the total perimeter of the polygons in the region</h2>
+<a name="perimeter"/><h2>"perimeter" - Returns the total perimeter of the polygons in the region</h2>
 <keyword name="perimeter"/>
-<a name="perimeter"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.perimeter</tt></li>
 </ul>
@@ -1365,9 +1365,9 @@ raw mode is chosen (see <a href="#raw">raw</a>).
 </p><p>
 The returned value gives the perimeter in micrometer units.
 </p>
-<h2>"polygons" - Returns polygons from edge pairs</h2>
+<a name="polygons"/><h2>"polygons" - Returns polygons from edge pairs</h2>
 <keyword name="polygons"/>
-<a name="polygons"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.polygons([ enlargement ])</tt></li>
 </ul>
@@ -1379,15 +1379,15 @@ edges etc.) an enlargement parameter can be specified which will make the
 resulting polygon somewhat larger than the original edge pair. If the enlargement
 parameter is 0, special edge pairs with an area of 0 will be dropped.
 </p>
-<h2>"polygons?" - Returns true, if the layer is a polygon layer</h2>
+<a name="polygons?"/><h2>"polygons?" - Returns true, if the layer is a polygon layer</h2>
 <keyword name="polygons?"/>
-<a name="polygons?"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.polygons?</tt></li>
 </ul>
-<h2>"pull_inside" - Selects shapes or regions of other which are inside polygons from the this region</h2>
+<a name="pull_inside"/><h2>"pull_inside" - Selects shapes or regions of other which are inside polygons from the this region</h2>
 <keyword name="pull_inside"/>
-<a name="pull_inside"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.pull_inside(other)</tt></li>
 </ul>
@@ -1402,9 +1402,9 @@ provides a way to pull shapes from other to the hierarchy to self.
 </p><p>
 This method is available for polygon layers. Other needs to be a polygon layer too.
 </p>
-<h2>"pull_interacting" - Selects shapes or edges of other which touch or overlap shapes from the this region</h2>
+<a name="pull_interacting"/><h2>"pull_interacting" - Selects shapes or edges of other which touch or overlap shapes from the this region</h2>
 <keyword name="pull_interacting"/>
-<a name="pull_interacting"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.pull_interacting(other)</tt></li>
 </ul>
@@ -1422,9 +1422,9 @@ This method will neither modify self nor other.
 This method is available for polygon layers. Other can be an edge or polygon layer. 
 Edges or polygons can be selected with respect to polygons of self.
 </p>
-<h2>"pull_overlapping" - Selects shapes or regions of other which overlap shapes from the this region</h2>
+<a name="pull_overlapping"/><h2>"pull_overlapping" - Selects shapes or regions of other which overlap shapes from the this region</h2>
 <keyword name="pull_overlapping"/>
-<a name="pull_overlapping"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.pull_overlapping(other)</tt></li>
 </ul>
@@ -1439,9 +1439,9 @@ provides a way to pull shapes from other to the hierarchy to self.
 </p><p>
 This method is available for polygon layers. Other needs to be a polygon layer too.
 </p>
-<h2>"raw" - Marks a layer as raw</h2>
+<a name="raw"/><h2>"raw" - Marks a layer as raw</h2>
 <keyword name="raw"/>
-<a name="raw"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.raw</tt></li>
 </ul>
@@ -1466,9 +1466,9 @@ l.raw
 </p><p>
 To avoid that, use the <a href="#dup">dup</a> method to create a real (deep) copy.
 </p>
-<h2>"rectangles" - Selects all rectangle polygons from the input</h2>
+<a name="rectangles"/><h2>"rectangles" - Selects all rectangle polygons from the input</h2>
 <keyword name="rectangles"/>
-<a name="rectangles"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.rectangles</tt></li>
 </ul>
@@ -1477,9 +1477,9 @@ This method is available for polygon layers. By default "merged" semantics appli
 i.e. all polygons are merged before rectangles are selected (see <a href="#clean">clean</a> and <a href="#raw">raw</a>).
 <a href="#non_rectangles">non_rectangles</a> will select all non-rectangles.
 </p>
-<h2>"rectilinear" - Selects all rectilinear polygons from the input</h2>
+<a name="rectilinear"/><h2>"rectilinear" - Selects all rectilinear polygons from the input</h2>
 <keyword name="rectilinear"/>
-<a name="rectilinear"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.rectilinear</tt></li>
 </ul>
@@ -1488,9 +1488,9 @@ This method is available for polygon layers. By default "merged" semantics appli
 i.e. all polygons are merged before rectilinear polygons are selected (see <a href="#clean">clean</a> and <a href="#raw">raw</a>).
 <a href="#non_rectilinear">non_rectilinear</a> will select all non-rectangles.
 </p>
-<h2>"rotate" - Rotates a layer (modifies the layer)</h2>
+<a name="rotate"/><h2>"rotate" - Rotates a layer (modifies the layer)</h2>
 <keyword name="rotate"/>
-<a name="rotate"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.rotate(a)</tt></li>
 </ul>
@@ -1498,9 +1498,9 @@ i.e. all polygons are merged before rectilinear polygons are selected (see <a hr
 Rotates the input by the given angle (in degree). The layer that this method is called 
 upon is modified and the modified version is returned for further processing.
 </p>
-<h2>"rotated" - Rotates a layer</h2>
+<a name="rotated"/><h2>"rotated" - Rotates a layer</h2>
 <keyword name="rotated"/>
-<a name="rotated"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.rotated(a)</tt></li>
 </ul>
@@ -1516,9 +1516,9 @@ The following image shows the effect of the "rotated" method:
 </tr>
 </table>
 </p>
-<h2>"rounded_corners" - Applies corner rounding to each corner of the polygon</h2>
+<a name="rounded_corners"/><h2>"rounded_corners" - Applies corner rounding to each corner of the polygon</h2>
 <keyword name="rounded_corners"/>
-<a name="rounded_corners"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.rounded_corners(inner, outer, n)</tt></li>
 </ul>
@@ -1545,9 +1545,9 @@ a larger radius.
 </tr>
 </table>
 </p>
-<h2>"scale" - Scales a layer (modifies the layer)</h2>
+<a name="scale"/><h2>"scale" - Scales a layer (modifies the layer)</h2>
 <keyword name="scale"/>
-<a name="scale"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.scale(f)</tt></li>
 </ul>
@@ -1556,9 +1556,9 @@ Scales the input. After scaling, features have a f times
 bigger dimension. The layer that this method is called upon is modified and
 the modified version is returned for further processing.
 </p>
-<h2>"scaled" - Scales a layer</h2>
+<a name="scaled"/><h2>"scaled" - Scales a layer</h2>
 <keyword name="scaled"/>
-<a name="scaled"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.scaled(f)</tt></li>
 </ul>
@@ -1574,9 +1574,9 @@ The following images shows the effect of the "scaled" method:
 </tr>
 </table>
 </p>
-<h2>"second_edges" - Returns the second edges of an edge pair collection</h2>
+<a name="second_edges"/><h2>"second_edges" - Returns the second edges of an edge pair collection</h2>
 <keyword name="second_edges"/>
-<a name="second_edges"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.second_edges</tt></li>
 </ul>
@@ -1584,9 +1584,9 @@ The following images shows the effect of the "scaled" method:
 Applies to edge pair collections only.
 Returns the second edges of the edge pairs in the collection.
 </p>
-<h2>"select" - Selects edges, edge pairs or polygons based on evaluation of a block</h2>
+<a name="select"/><h2>"select" - Selects edges, edge pairs or polygons based on evaluation of a block</h2>
 <keyword name="select"/>
-<a name="select"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.select { |object| ... }</tt></li>
 </ul>
@@ -1604,9 +1604,9 @@ Here is a (slow) equivalent of the area selection method:
 new_layer = layer.select { |polygon| polygon.area &gt;= 10.0 }
 </pre>
 </p>
-<h2>"select_inside" - Selects shapes or regions of self which are inside the other region</h2>
+<a name="select_inside"/><h2>"select_inside" - Selects shapes or regions of self which are inside the other region</h2>
 <keyword name="select_inside"/>
-<a name="select_inside"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.select_inside(other)</tt></li>
 </ul>
@@ -1621,9 +1621,9 @@ is <a href="#inside">inside</a>.
 </p><p>
 This method is available for polygon layers.
 </p>
-<h2>"select_interacting" - Selects shapes or regions of self which touch or overlap shapes from the other region</h2>
+<a name="select_interacting"/><h2>"select_interacting" - Selects shapes or regions of self which touch or overlap shapes from the other region</h2>
 <keyword name="select_interacting"/>
-<a name="select_interacting"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.select_interacting(other)</tt></li>
 </ul>
@@ -1637,9 +1637,9 @@ is <a href="#interacting">interacting</a>.
 This method is available for polygon and edge layers. Edges can be selected
 with respect to other edges or polygons.
 </p>
-<h2>"select_not_inside" - Selects shapes or regions of self which are not inside the other region</h2>
+<a name="select_not_inside"/><h2>"select_not_inside" - Selects shapes or regions of self which are not inside the other region</h2>
 <keyword name="select_not_inside"/>
-<a name="select_not_inside"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.select_not_inside(other)</tt></li>
 </ul>
@@ -1654,9 +1654,9 @@ is <a href="#not_inside">not_inside</a>.
 </p><p>
 This method is available for polygon layers.
 </p>
-<h2>"select_not_interacting" - Selects shapes or regions of self which do not touch or overlap shapes from the other region</h2>
+<a name="select_not_interacting"/><h2>"select_not_interacting" - Selects shapes or regions of self which do not touch or overlap shapes from the other region</h2>
 <keyword name="select_not_interacting"/>
-<a name="select_not_interacting"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.select_interacting(other)</tt></li>
 </ul>
@@ -1670,9 +1670,9 @@ is <a href="#not_interacting">not_interacting</a>.
 This method is available for polygon and edge layers. Edges can be selected
 with respect to other edges or polygons.
 </p>
-<h2>"select_not_outside" - Selects shapes or regions of self which are not outside the other region</h2>
+<a name="select_not_outside"/><h2>"select_not_outside" - Selects shapes or regions of self which are not outside the other region</h2>
 <keyword name="select_not_outside"/>
-<a name="select_not_outside"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.select_not_outside(other)</tt></li>
 </ul>
@@ -1687,9 +1687,9 @@ is <a href="#not_outside">not_outside</a>.
 </p><p>
 This method is available for polygon layers.
 </p>
-<h2>"select_not_overlapping" - Selects shapes or regions of self which do not overlap shapes from the other region</h2>
+<a name="select_not_overlapping"/><h2>"select_not_overlapping" - Selects shapes or regions of self which do not overlap shapes from the other region</h2>
 <keyword name="select_not_overlapping"/>
-<a name="select_not_overlapping"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.select_not_overlapping(other)</tt></li>
 </ul>
@@ -1703,9 +1703,9 @@ is <a href="#not_overlapping">not_overlapping</a>.
 This method is available for polygon and edge layers. Edges can be selected
 with respect to other edges or polygons.
 </p>
-<h2>"select_outside" - Selects shapes or regions of self which are outside the other region</h2>
+<a name="select_outside"/><h2>"select_outside" - Selects shapes or regions of self which are outside the other region</h2>
 <keyword name="select_outside"/>
-<a name="select_outside"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.select_outside(other)</tt></li>
 </ul>
@@ -1720,9 +1720,9 @@ is <a href="#outside">outside</a>.
 </p><p>
 This method is available for polygon layers.
 </p>
-<h2>"select_overlapping" - Selects shapes or regions of self which overlap shapes from the other region</h2>
+<a name="select_overlapping"/><h2>"select_overlapping" - Selects shapes or regions of self which overlap shapes from the other region</h2>
 <keyword name="select_overlapping"/>
-<a name="select_overlapping"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.select_overlapping(other)</tt></li>
 </ul>
@@ -1736,18 +1736,18 @@ is <a href="#overlapping">overlapping</a>.
 This method is available for polygon and edge layers. Edges can be selected
 with respect to other edges or polygons.
 </p>
-<h2>"sep" - An alias for "separation"</h2>
+<a name="sep"/><h2>"sep" - An alias for "separation"</h2>
 <keyword name="sep"/>
-<a name="sep"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.sep(value [, options])</tt></li>
 </ul>
 <p>
 See <a href="#separation">separation</a> for a description of that method
 </p>
-<h2>"separation" - A two-layer spacing check</h2>
+<a name="separation"/><h2>"separation" - A two-layer spacing check</h2>
 <keyword name="separation"/>
-<a name="separation"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.separation(other_layer, value [, options])</tt></li>
 </ul>
@@ -1774,9 +1774,9 @@ The following image shows the effect of the separation check (layer1: red, layer
 </tr>
 </table>
 </p>
-<h2>"size" - Polygon sizing (per-edge biasing, modifies the layer)</h2>
+<a name="size"/><h2>"size" - Polygon sizing (per-edge biasing, modifies the layer)</h2>
 <keyword name="size"/>
-<a name="size"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.size(d [, mode])</tt></li>
 <li><tt>layer.size(dx, dy [, mode]))</tt></li>
@@ -1785,9 +1785,9 @@ The following image shows the effect of the separation check (layer1: red, layer
 See <a href="#sized">sized</a>. The size method basically does the same but modifies the layer
 it is called on. The input layer is returned and available for further processing.
 </p>
-<h2>"sized" - Polygon sizing (per-edge biasing)</h2>
+<a name="sized"/><h2>"sized" - Polygon sizing (per-edge biasing)</h2>
 <keyword name="sized"/>
-<a name="sized"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.sized(d [, mode])</tt></li>
 <li><tt>layer.sized(dx, dy [, mode]))</tt></li>
@@ -1842,9 +1842,9 @@ The following images show the effect of various forms of the "sized" method:
 </tr>
 </table>
 </p>
-<h2>"smoothed" - Smoothes the polygons of the region</h2>
+<a name="smoothed"/><h2>"smoothed" - Smoothes the polygons of the region</h2>
 <keyword name="smoothed"/>
-<a name="smoothed"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.smoothed(d)</tt></li>
 </ul>
@@ -1856,9 +1856,9 @@ than the given distance d from the original polygon.
 This method return a layer wit the modified polygons. Merged semantics applies for this
 method (see <a href="#raw">raw</a> and <a href="#clean">clean</a>).
 </p>
-<h2>"snap" - Brings each vertex on the given grid (g or gx/gy for x or y direction)</h2>
+<a name="snap"/><h2>"snap" - Brings each vertex on the given grid (g or gx/gy for x or y direction)</h2>
 <keyword name="snap"/>
-<a name="snap"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.snap(g)</tt></li>
 <li><tt>layer.snap(gx, gy)</tt></li>
@@ -1874,9 +1874,9 @@ without modifying the layer is <a href="#snapped">snapped</a>.
 </p><p>
 This method requires a polygon layer. Merged semantics applies (see <a href="#raw">raw</a> and <a href="#clean">clean</a>).
 </p>
-<h2>"snapped" - Returns a snapped version of the layer</h2>
+<a name="snapped"/><h2>"snapped" - Returns a snapped version of the layer</h2>
 <keyword name="snapped"/>
-<a name="snapped"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.snapped(g)</tt></li>
 <li><tt>layer.snapped(gx, gy)</tt></li>
@@ -1885,9 +1885,9 @@ This method requires a polygon layer. Merged semantics applies (see <a href="#ra
 See <a href="#snap">snap</a> for a description of the functionality. In contrast to <a href="#snap">snap</a>, this method does
 not modify the layer but returns a snapped copy.
 </p>
-<h2>"space" - A space check</h2>
+<a name="space"/><h2>"space" - A space check</h2>
 <keyword name="space"/>
-<a name="space"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.space(value [, options])</tt></li>
 </ul>
@@ -1920,9 +1920,9 @@ The following image shows the effect of the space check:
 </tr>
 </table>
 </p>
-<h2>"start_segments" - Returns the part at the beginning of each edge</h2>
+<a name="start_segments"/><h2>"start_segments" - Returns the part at the beginning of each edge</h2>
 <keyword name="start_segments"/>
-<a name="start_segments"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.start_segments(length)</tt></li>
 <li><tt>layer.start_segments(length, fraction)</tt></li>
@@ -1943,9 +1943,9 @@ The following images show the effect of the method:
 </tr>
 </table>
 </p>
-<h2>"strict" - Marks a layer for strict handling</h2>
+<a name="strict"/><h2>"strict" - Marks a layer for strict handling</h2>
 <keyword name="strict"/>
-<a name="strict"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.strict</tt></li>
 </ul>
@@ -1960,9 +1960,9 @@ See <a href="#non_strict">non_strict</a> about how to reset this mode.
 </p><p>
 This feature has been introduced in version 0.23.2.
 </p>
-<h2>"strict?" - Returns true, if strict handling is enabled for this layer</h2>
+<a name="strict?"/><h2>"strict?" - Returns true, if strict handling is enabled for this layer</h2>
 <keyword name="strict?"/>
-<a name="strict?"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.is_strict?</tt></li>
 </ul>
@@ -1971,9 +1971,9 @@ See <a href="#strict">strict</a> for a discussion of strict handling.
 </p><p>
 This feature has been introduced in version 0.23.2.
 </p>
-<h2>"texts" - Selects texts from an original layer</h2>
+<a name="texts"/><h2>"texts" - Selects texts from an original layer</h2>
 <keyword name="texts"/>
-<a name="texts"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.texts</tt></li>
 <li><tt>layer.texts(p)</tt></li>
@@ -2008,9 +2008,9 @@ t = input(1, 0).texts(pattern("A*"))
 t = input(1, 0).texts(text("A*"))
 </pre>
 </p>
-<h2>"transform" - Transforms a layer (modifies the layer)</h2>
+<a name="transform"/><h2>"transform" - Transforms a layer (modifies the layer)</h2>
 <keyword name="transform"/>
-<a name="transform"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.transform(t)</tt></li>
 </ul>
@@ -2018,9 +2018,9 @@ t = input(1, 0).texts(text("A*"))
 Like <a href="#transform">transform</a>, but modifies the input and returns a reference to it for
 further processing.
 </p>
-<h2>"transformed" - Transforms a layer</h2>
+<a name="transformed"/><h2>"transformed" - Transforms a layer</h2>
 <keyword name="transformed"/>
-<a name="transformed"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.transformed(t)</tt></li>
 </ul>
@@ -2039,9 +2039,9 @@ The following image shows the effect of the "moved" method:
 </tr>
 </table>
 </p>
-<h2>"width" - A width check</h2>
+<a name="width"/><h2>"width" - A width check</h2>
 <keyword name="width"/>
-<a name="width"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.width(value [, options])</tt></li>
 </ul>
@@ -2107,9 +2107,9 @@ The following images show the effect of various forms of the width check:
 </tr>
 </table>
 </p>
-<h2>"with_angle" - Selects edges by their angle</h2>
+<a name="with_angle"/><h2>"with_angle" - Selects edges by their angle</h2>
 <keyword name="with_angle"/>
-<a name="with_angle"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.with_angle(min .. max)</tt></li>
 <li><tt>layer.with_angle(value)</tt></li>
@@ -2142,9 +2142,9 @@ The following images demonstrate some use cases of <a href="#with_angle">with_an
 </tr>
 </table>
 </p>
-<h2>"with_area" - Selects polygons by area</h2>
+<a name="with_area"/><h2>"with_area" - Selects polygons by area</h2>
 <keyword name="with_area"/>
-<a name="with_area"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.with_area(min .. max)</tt></li>
 <li><tt>layer.with_area(value)</tt></li>
@@ -2158,9 +2158,9 @@ The third form basically is equivalent to the first form, but
 allows specification of nil for min or max indicating no lower or 
 upper limit.
 </p>
-<h2>"with_bbox_height" - Selects polygons by the height of the bounding box</h2>
+<a name="with_bbox_height"/><h2>"with_bbox_height" - Selects polygons by the height of the bounding box</h2>
 <keyword name="with_bbox_height"/>
-<a name="with_bbox_height"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.with_bbox_height(min .. max)</tt></li>
 <li><tt>layer.with_bbox_height(value)</tt></li>
@@ -2173,9 +2173,9 @@ bounding box.
 </p><p>
 This method is available for polygon layers only.
 </p>
-<h2>"with_bbox_max" - Selects polygons by the maximum dimension of the bounding box</h2>
+<a name="with_bbox_max"/><h2>"with_bbox_max" - Selects polygons by the maximum dimension of the bounding box</h2>
 <keyword name="with_bbox_max"/>
-<a name="with_bbox_max"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.with_bbox_max(min .. max)</tt></li>
 <li><tt>layer.with_bbox_max(value)</tt></li>
@@ -2189,9 +2189,9 @@ the bounding box, whichever is larger.
 </p><p>
 This method is available for polygon layers only.
 </p>
-<h2>"with_bbox_min" - Selects polygons by the minimum dimension of the bounding box</h2>
+<a name="with_bbox_min"/><h2>"with_bbox_min" - Selects polygons by the minimum dimension of the bounding box</h2>
 <keyword name="with_bbox_min"/>
-<a name="with_bbox_min"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.with_bbox_min(min .. max)</tt></li>
 <li><tt>layer.with_bbox_min(value)</tt></li>
@@ -2205,9 +2205,9 @@ the bounding box, whichever is smaller.
 </p><p>
 This method is available for polygon layers only.
 </p>
-<h2>"with_bbox_width" - Selects polygons by the width of the bounding box</h2>
+<a name="with_bbox_width"/><h2>"with_bbox_width" - Selects polygons by the width of the bounding box</h2>
 <keyword name="with_bbox_width"/>
-<a name="with_bbox_width"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.with_bbox_width(min .. max)</tt></li>
 <li><tt>layer.with_bbox_width(value)</tt></li>
@@ -2220,9 +2220,9 @@ bounding box.
 </p><p>
 This method is available for polygon layers only.
 </p>
-<h2>"with_length" - Selects edges by their length</h2>
+<a name="with_length"/><h2>"with_length" - Selects edges by their length</h2>
 <keyword name="with_length"/>
-<a name="with_length"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.with_length(min .. max)</tt></li>
 <li><tt>layer.with_length(value)</tt></li>
@@ -2237,9 +2237,9 @@ max indicating that there is no lower or upper limit.
 </p><p>
 This method is available for edge layers only.
 </p>
-<h2>"with_perimeter" - Selects polygons by perimeter</h2>
+<a name="with_perimeter"/><h2>"with_perimeter" - Selects polygons by perimeter</h2>
 <keyword name="with_perimeter"/>
-<a name="with_perimeter"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.with_perimeter(min .. max)</tt></li>
 <li><tt>layer.with_perimeter(value)</tt></li>
@@ -2255,9 +2255,9 @@ upper limit.
 </p><p>
 This method is available for polygon layers only.
 </p>
-<h2>"without_angle" - Selects edges by the their angle</h2>
+<a name="without_angle"/><h2>"without_angle" - Selects edges by the their angle</h2>
 <keyword name="without_angle"/>
-<a name="without_angle"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.without_angle(min .. max)</tt></li>
 <li><tt>layer.without_angle(value)</tt></li>
@@ -2268,9 +2268,9 @@ The method basically is the inverse of <a href="#with_angle">with_angle</a>. It
 of the edge layer or corners of the polygons which do not have the given angle (second form) or whose angle
 is not inside the given interval (first and third form).
 </p>
-<h2>"without_area" - Selects polygons by area</h2>
+<a name="without_area"/><h2>"without_area" - Selects polygons by area</h2>
 <keyword name="without_area"/>
-<a name="without_area"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.without_area(min .. max)</tt></li>
 <li><tt>layer.without_area(value)</tt></li>
@@ -2283,9 +2283,9 @@ the given interval.
 </p><p>
 This method is available for polygon layers only.
 </p>
-<h2>"without_bbox_height" - Selects polygons by the height of the bounding box</h2>
+<a name="without_bbox_height"/><h2>"without_bbox_height" - Selects polygons by the height of the bounding box</h2>
 <keyword name="without_bbox_height"/>
-<a name="without_bbox_height"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.without_bbox_height(min .. max)</tt></li>
 <li><tt>layer.without_bbox_height(value)</tt></li>
@@ -2298,9 +2298,9 @@ bounding box.
 </p><p>
 This method is available for polygon layers only.
 </p>
-<h2>"without_bbox_max" - Selects polygons by the maximum dimension of the bounding box</h2>
+<a name="without_bbox_max"/><h2>"without_bbox_max" - Selects polygons by the maximum dimension of the bounding box</h2>
 <keyword name="without_bbox_max"/>
-<a name="without_bbox_max"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.without_bbox_max(min .. max)</tt></li>
 <li><tt>layer.without_bbox_max(value)</tt></li>
@@ -2314,9 +2314,9 @@ the bounding box, whichever is larger.
 </p><p>
 This method is available for polygon layers only.
 </p>
-<h2>"without_bbox_min" - Selects polygons by the minimum dimension of the bounding box</h2>
+<a name="without_bbox_min"/><h2>"without_bbox_min" - Selects polygons by the minimum dimension of the bounding box</h2>
 <keyword name="without_bbox_min"/>
-<a name="without_bbox_min"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.without_bbox_min(min .. max)</tt></li>
 <li><tt>layer.without_bbox_min(value)</tt></li>
@@ -2330,9 +2330,9 @@ the bounding box, whichever is smaller.
 </p><p>
 This method is available for polygon layers only.
 </p>
-<h2>"without_bbox_width" - Selects polygons by the width of the bounding box</h2>
+<a name="without_bbox_width"/><h2>"without_bbox_width" - Selects polygons by the width of the bounding box</h2>
 <keyword name="without_bbox_width"/>
-<a name="without_bbox_width"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.without_bbox_width(min .. max)</tt></li>
 <li><tt>layer.without_bbox_width(value)</tt></li>
@@ -2345,9 +2345,9 @@ bounding box.
 </p><p>
 This method is available for polygon layers only.
 </p>
-<h2>"without_length" - Selects edges by the their length</h2>
+<a name="without_length"/><h2>"without_length" - Selects edges by the their length</h2>
 <keyword name="without_length"/>
-<a name="without_length"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.without_length(min .. max)</tt></li>
 <li><tt>layer.without_length(value)</tt></li>
@@ -2360,9 +2360,9 @@ not inside the given interval (first and third form).
 </p><p>
 This method is available for edge layers only.
 </p>
-<h2>"without_perimeter" - Selects polygons by perimeter</h2>
+<a name="without_perimeter"/><h2>"without_perimeter" - Selects polygons by perimeter</h2>
 <keyword name="without_perimeter"/>
-<a name="without_perimeter"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.without_perimeter(min .. max)</tt></li>
 <li><tt>layer.without_perimeter(value)</tt></li>
@@ -2375,9 +2375,9 @@ the given interval.
 </p><p>
 This method is available for polygon layers only.
 </p>
-<h2>"xor" - Boolean XOR operation</h2>
+<a name="xor"/><h2>"xor" - Boolean XOR operation</h2>
 <keyword name="xor"/>
-<a name="xor"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layer.xor(other)</tt></li>
 </ul>
@@ -2397,9 +2397,9 @@ on polygons and edges (layer1: red, layer2: blue):
 </tr>
 </table>
 </p>
-<h2>"|" - Boolean OR operation</h2>
+<a name="|"/><h2>"|" - Boolean OR operation</h2>
 <keyword name="|"/>
-<a name="|"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>self | other</tt></li>
 </ul>
diff --git a/src/lay/lay/doc/about/drc_ref_netter.xml b/src/lay/lay/doc/about/drc_ref_netter.xml
index 8324c8c14..c56e060df 100644
--- a/src/lay/lay/doc/about/drc_ref_netter.xml
+++ b/src/lay/lay/doc/about/drc_ref_netter.xml
@@ -61,9 +61,9 @@ Further functionality of the Netter object:
 More methods will be added in the future to support network-related features.
 </p>
 <h2-index/>
-<h2>"antenna_check" - Performs an antenna check</h2>
+<a name="antenna_check"/><h2>"antenna_check" - Performs an antenna check</h2>
 <keyword name="antenna_check"/>
-<a name="antenna_check"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>antenna_check(gate, metal, ratio, [ diode_specs ... ])</tt></li>
 </ul>
@@ -137,18 +137,18 @@ The error shapes produced by the antenna check are copies
 of the metal shapes on the metal layers of each network 
 violating the antenna rule.
 </p>
-<h2>"clear_connections" - Clears all connections stored so far</h2>
+<a name="clear_connections"/><h2>"clear_connections" - Clears all connections stored so far</h2>
 <keyword name="clear_connections"/>
-<a name="clear_connections"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>clear_connections</tt></li>
 </ul>
 <p>
 See <a href="#connect">connect</a> for more details.
 </p>
-<h2>"connect" - Specifies a connection between two layers</h2>
+<a name="connect"/><h2>"connect" - Specifies a connection between two layers</h2>
 <keyword name="connect"/>
-<a name="connect"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>connect(a, b)</tt></li>
 </ul>
@@ -167,9 +167,9 @@ joins.
 Connections are accumulated. The connections defined so far
 can be cleared with <a href="#clear_connections">clear_connections</a>.
 </p>
-<h2>"connect_global" - Connects a layer with a global net</h2>
+<a name="connect_global"/><h2>"connect_global" - Connects a layer with a global net</h2>
 <keyword name="connect_global"/>
-<a name="connect_global"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>connect_global(l, name)</tt></li>
 </ul>
@@ -179,9 +179,9 @@ Global nets are common to all cells. Global nets automatically connect to parent
 cells throughs implied pins. An example is the substrate (bulk) net which connects
 to shapes belonging to tie-down diodes.
 </p>
-<h2>"connect_implicit" - Specifies a search pattern for labels which create implicit net connections</h2>
+<a name="connect_implicit"/><h2>"connect_implicit" - Specifies a search pattern for labels which create implicit net connections</h2>
 <keyword name="connect_implicit"/>
-<a name="connect_implicit"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>connect_implicit(label_pattern)</tt></li>
 <li><tt>connect_implicit(cell_pattern, label_pattern)</tt></li>
@@ -205,9 +205,9 @@ combined.
 The implicit connections are applied on the next net extraction and cleared
 on "clear_connections".
 </p>
-<h2>"device_scaling" - Specifies a dimension scale factor for the geometrical device properties</h2>
+<a name="device_scaling"/><h2>"device_scaling" - Specifies a dimension scale factor for the geometrical device properties</h2>
 <keyword name="device_scaling"/>
-<a name="device_scaling"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>device_scaling(factor)</tt></li>
 </ul>
@@ -216,9 +216,9 @@ Specifying a factor of 2 will make all devices being extracted as if the
 geometries were two times larger. This feature is useful when the drawn layout
 does not correspond to the physical dimensions.
 </p>
-<h2>"extract_devices" - Extracts devices based on the given extractor class, name and device layer selection</h2>
+<a name="extract_devices"/><h2>"extract_devices" - Extracts devices based on the given extractor class, name and device layer selection</h2>
 <keyword name="extract_devices"/>
-<a name="extract_devices"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>extract_devices(extractor, layer_hash)</tt></li>
 <li><tt>extract_devices(extractor_class, name, layer_hash)</tt></li>
@@ -229,11 +229,27 @@ form, the extractor object is given. In the second form, the extractor's
 class object and the new extractor's name is given.
 </p><p>
 The device extractor is either an instance of one of the predefined extractor
-classes (e.g. obtained from the utility methods such as <a href="#mos4">mos4</a>) or a custom class. 
+classes (e.g. obtained from the utility methods such as <a href="/about/drc_ref_global.xml#mos4">global#mos4</a>) or a custom class. 
 It provides the
 algorithms for deriving the device parameters from the device geometry. It needs 
 several device recognition layers which are passed in the layer hash.
 </p><p>
+Predefined device extractors are:
+</p><p>
+<ul>
+<li><a href="/about/drc_ref_global.xml#mos3">global#mos3</a> - A three-terminal MOS transistor </li>
+<li><a href="/about/drc_ref_global.xml#mos4">global#mos4</a> - A four-terminal MOS transistor </li>
+<li><a href="/about/drc_ref_global.xml#dmos3">global#dmos3</a> - A three-terminal MOS asymmetric transistor </li>
+<li><a href="/about/drc_ref_global.xml#dmos4">global#dmos4</a> - A four-terminal MOS asymmetric transistor </li>
+<li><a href="/about/drc_ref_global.xml#bjt3">global#bjt3</a> - A three-terminal bipolar transistor </li>
+<li><a href="/about/drc_ref_global.xml#bjt4">global#bjt4</a> - A four-terminal bipolar transistor </li>
+<li><a href="/about/drc_ref_global.xml#diode">global#diode</a> - A planar diode </li>
+<li><a href="/about/drc_ref_global.xml#resistor">global#resistor</a> - A resistor </li>
+<li><a href="/about/drc_ref_global.xml#resistor_with_bulk">global#resistor_with_bulk</a> - A resistor with a separate bulk terminal </li>
+<li><a href="/about/drc_ref_global.xml#capacitor">global#capacitor</a> - A capacitor </li>
+<li><a href="/about/drc_ref_global.xml#capacitor_with_bulk">global#capacitor_with_bulk</a> - A capacitor with a separate bulk terminal </li>
+</ul>
+</p><p>
 Each device class (e.g. n-MOS/p-MOS or high Vt/low Vt) needs it's own instance
 of device extractor. The device extractor beside the algorithm and specific 
 extraction settings defines the name of the device to be built.
@@ -256,9 +272,9 @@ gate    = nactive &amp; poly  # gate area
 extract_devices(mos4("NMOS4"), { :SD =&gt; nsd, :G =&gt; gate, :P =&gt; poly, :W =&gt; bulk })
 </pre>
 </p>
-<h2>"l2n_data" - Gets the internal <class_doc href="LayoutToNetlist">LayoutToNetlist</class_doc> object</h2>
+<a name="l2n_data"/><h2>"l2n_data" - Gets the internal <class_doc href="LayoutToNetlist">LayoutToNetlist</class_doc> object</h2>
 <keyword name="l2n_data"/>
-<a name="l2n_data"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>l2n_data</tt></li>
 </ul>
@@ -266,9 +282,9 @@ extract_devices(mos4("NMOS4"), { :SD =&gt; nsd, :G =&gt; gate, :P =&gt; poly, :W
 The <class_doc href="LayoutToNetlist">LayoutToNetlist</class_doc> object provides access to the internal details of
 the netter object.
 </p>
-<h2>"netlist" - Gets the extracted netlist or triggers extraction if not done yet</h2>
+<a name="netlist"/><h2>"netlist" - Gets the extracted netlist or triggers extraction if not done yet</h2>
 <keyword name="netlist"/>
-<a name="netlist"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>netlist</tt></li>
 </ul>
diff --git a/src/lay/lay/doc/about/drc_ref_source.xml b/src/lay/lay/doc/about/drc_ref_source.xml
index 3a2b42bea..a620c0b4b 100644
--- a/src/lay/lay/doc/about/drc_ref_source.xml
+++ b/src/lay/lay/doc/about/drc_ref_source.xml
@@ -13,9 +13,9 @@ A source specifies where to take layout from. That includes the actual layout,
 the top cell and options such as clip/query boxes, cell filters etc.
 </p>
 <h2-index/>
-<h2>"cell" - Specifies input from a specific cell</h2>
+<a name="cell"/><h2>"cell" - Specifies input from a specific cell</h2>
 <keyword name="cell"/>
-<a name="cell"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>source.cell(name)</tt></li>
 </ul>
@@ -23,21 +23,21 @@ the top cell and options such as clip/query boxes, cell filters etc.
 This method will create a new source that delivers shapes from the 
 specified cell. 
 </p>
-<h2>"cell_name" - Returns the name of the currently selected cell</h2>
+<a name="cell_name"/><h2>"cell_name" - Returns the name of the currently selected cell</h2>
 <keyword name="cell_name"/>
-<a name="cell_name"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>cell_name</tt></li>
 </ul>
-<h2>"cell_obj" - Returns the <class_doc href="Cell">Cell</class_doc> object of the currently selected cell</h2>
+<a name="cell_obj"/><h2>"cell_obj" - Returns the <class_doc href="Cell">Cell</class_doc> object of the currently selected cell</h2>
 <keyword name="cell_obj"/>
-<a name="cell_obj"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>cell_obj</tt></li>
 </ul>
-<h2>"clip" - Specifies clipped input</h2>
+<a name="clip"/><h2>"clip" - Specifies clipped input</h2>
 <keyword name="clip"/>
-<a name="clip"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>source.clip(box)</tt></li>
 <li><tt>source.clip(p1, p2)</tt></li>
@@ -54,9 +54,9 @@ This method will create a new source which delivers the shapes
 from that region clipped to the rectangle. A method doing the 
 same but without clipping is <a href="#touching">touching</a> or <a href="#overlapping">overlapping</a>.
 </p>
-<h2>"extent" - Returns a layer with the bounding box of the selected layout</h2>
+<a name="extent"/><h2>"extent" - Returns a layer with the bounding box of the selected layout</h2>
 <keyword name="extent"/>
-<a name="extent"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>source.extent</tt></li>
 </ul>
@@ -67,9 +67,9 @@ The extent function is useful to invert a layer:
 inverse_1 = extent.sized(100.0) - input(1, 0)
 </pre>
 </p>
-<h2>"input" - Specifies input from a source</h2>
+<a name="input"/><h2>"input" - Specifies input from a source</h2>
 <keyword name="input"/>
-<a name="input"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>source.input(layer)</tt></li>
 <li><tt>source.input(layer, datatype)</tt></li>
@@ -108,9 +108,9 @@ only. If you only want to see texts, use <a href="#labels">labels</a> to create
 </p><p>
 Use the global version of "input" without a source object to address the default source.
 </p>
-<h2>"labels" - Gets the labels (texts) from an input layer</h2>
+<a name="labels"/><h2>"labels" - Gets the labels (texts) from an input layer</h2>
 <keyword name="labels"/>
-<a name="labels"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>source.labels(layer)</tt></li>
 <li><tt>source.labels(layer, datatype)</tt></li>
@@ -125,9 +125,9 @@ layer.
 </p><p>
 Use the global version of "labels" without a source object to address the default source.
 </p>
-<h2>"layers" - Gets the layers the source contains</h2>
+<a name="layers"/><h2>"layers" - Gets the layers the source contains</h2>
 <keyword name="layers"/>
-<a name="layers"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>source.layers</tt></li>
 </ul>
@@ -149,24 +149,24 @@ clip_box.insert(box(0.um, -4.um, 4.um, 0.um))
 layers.each { |l| (input(l) &amp; clip_box).output(l) }
 </pre>
 </p>
-<h2>"layout" - Returns the <class_doc href="Layout">Layout</class_doc> object associated with this source</h2>
+<a name="layout"/><h2>"layout" - Returns the <class_doc href="Layout">Layout</class_doc> object associated with this source</h2>
 <keyword name="layout"/>
-<a name="layout"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>layout</tt></li>
 </ul>
-<h2>"make_layer" - Creates an empty polygon layer based on the hierarchy of the layout</h2>
+<a name="make_layer"/><h2>"make_layer" - Creates an empty polygon layer based on the hierarchy of the layout</h2>
 <keyword name="make_layer"/>
-<a name="make_layer"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>make_layer</tt></li>
 </ul>
 <p>
 This method delivers a new empty original layer.
 </p>
-<h2>"overlapping" - Specifies input selected from a region in overlapping mode</h2>
+<a name="overlapping"/><h2>"overlapping" - Specifies input selected from a region in overlapping mode</h2>
 <keyword name="overlapping"/>
-<a name="overlapping"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>source.overlapping(...)</tt></li>
 </ul>
@@ -180,15 +180,15 @@ the specified rectangle.
 <a href="#touching">touching</a> is a similar method which delivers shapes touching
 the search region with their bounding box (without the requirement to overlap)
 </p>
-<h2>"path" - Gets the path of the corresponding layout file or nil if there is no path</h2>
+<a name="path"/><h2>"path" - Gets the path of the corresponding layout file or nil if there is no path</h2>
 <keyword name="path"/>
-<a name="path"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>path</tt></li>
 </ul>
-<h2>"polygons" - Gets the polygon shapes (or shapes that can be converted polygons) from an input layer</h2>
+<a name="polygons"/><h2>"polygons" - Gets the polygon shapes (or shapes that can be converted polygons) from an input layer</h2>
 <keyword name="polygons"/>
-<a name="polygons"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>source.polygons(layer)</tt></li>
 <li><tt>source.polygons(layer, datatype)</tt></li>
@@ -204,9 +204,9 @@ This method is identical to <a href="#input">input</a> with respect to the optio
 </p><p>
 Use the global version of "polygons" without a source object to address the default source.
 </p>
-<h2>"select" - Adds cell name expressions to the cell filters</h2>
+<a name="select"/><h2>"select" - Adds cell name expressions to the cell filters</h2>
 <keyword name="select"/>
-<a name="select"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>source.select(filter1, filter2, ...)</tt></li>
 </ul>
@@ -249,9 +249,9 @@ l1 = layout_with_selection.input(1, 0)
 ...
 </pre>
 </p>
-<h2>"touching" - Specifies input selected from a region in touching mode</h2>
+<a name="touching"/><h2>"touching" - Specifies input selected from a region in touching mode</h2>
 <keyword name="touching"/>
-<a name="touching"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>source.touching(box)</tt></li>
 <li><tt>source.touching(p1, p2)</tt></li>
diff --git a/src/lay/lay/doc/about/lvs_ref_global.xml b/src/lay/lay/doc/about/lvs_ref_global.xml
index 940f6af21..c1afc715e 100644
--- a/src/lay/lay/doc/about/lvs_ref_global.xml
+++ b/src/lay/lay/doc/about/lvs_ref_global.xml
@@ -19,90 +19,90 @@ layers or specification of the layout source.
 For more details about the DRC functions see <a href="/about/drc_ref_global.xml">DRC::global</a>.
 </p>
 <h2-index/>
-<h2>"align" - Aligns the extracted netlist vs. the schematic by flattening circuits where required</h2>
+<a name="align"/><h2>"align" - Aligns the extracted netlist vs. the schematic by flattening circuits where required</h2>
 <keyword name="align"/>
-<a name="align"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>align</tt></li>
 </ul>
 <p>
 See <a href="/about/lvs_ref_netter.xml#align">Netter#align</a> for a description of that function.
 </p>
-<h2>"compare" - Compares the extracted netlist vs. the schematic</h2>
+<a name="compare"/><h2>"compare" - Compares the extracted netlist vs. the schematic</h2>
 <keyword name="compare"/>
-<a name="compare"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>compare</tt></li>
 </ul>
 <p>
 See <a href="/about/lvs_ref_netter.xml#compare">Netter#compare</a> for a description of that function.
 </p>
-<h2>"equivalent_pins" - Marks pins as equivalent</h2>
+<a name="equivalent_pins"/><h2>"equivalent_pins" - Marks pins as equivalent</h2>
 <keyword name="equivalent_pins"/>
-<a name="equivalent_pins"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>equivalent_pins(circuit, pins ...)</tt></li>
 </ul>
 <p>
 See <a href="/about/lvs_ref_netter.xml#equivalent_pins">Netter#equivalent_pins</a> for a description of that function.
 </p>
-<h2>"join_symmetric_nets" - Joins symmetric nets of selected circuits on the extracted netlist</h2>
+<a name="join_symmetric_nets"/><h2>"join_symmetric_nets" - Joins symmetric nets of selected circuits on the extracted netlist</h2>
 <keyword name="join_symmetric_nets"/>
-<a name="join_symmetric_nets"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>join_symmetric_nets(circuit_filter)</tt></li>
 </ul>
 <p>
 See <a href="/about/lvs_ref_netter.xml#join_symmetric_nets">Netter#join_symmetric_nets</a> for a description of that function.
 </p>
-<h2>"max_branch_complexity" - Configures the maximum branch complexity for ambiguous net matching</h2>
+<a name="max_branch_complexity"/><h2>"max_branch_complexity" - Configures the maximum branch complexity for ambiguous net matching</h2>
 <keyword name="max_branch_complexity"/>
-<a name="max_branch_complexity"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>max_branch_complexity(n)</tt></li>
 </ul>
 <p>
 See <a href="/about/lvs_ref_netter.xml#max_branch_complexity">Netter#max_branch_complexity</a> for a description of that function.
 </p>
-<h2>"max_depth" - Configures the maximum search depth for net match deduction</h2>
+<a name="max_depth"/><h2>"max_depth" - Configures the maximum search depth for net match deduction</h2>
 <keyword name="max_depth"/>
-<a name="max_depth"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>max_depth(n)</tt></li>
 </ul>
 <p>
 See <a href="/about/lvs_ref_netter.xml#max_depth">Netter#max_depth</a> for a description of that function.
 </p>
-<h2>"max_res" - Ignores resistors with a resistance above a certain value</h2>
+<a name="max_res"/><h2>"max_res" - Ignores resistors with a resistance above a certain value</h2>
 <keyword name="max_res"/>
-<a name="max_res"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>max_res(threshold)</tt></li>
 </ul>
 <p>
 See <a href="/about/lvs_ref_netter.xml#max_res">Netter#max_res</a> for a description of that function.
 </p>
-<h2>"min_caps" - Ignores capacitors with a capacitance below a certain value</h2>
+<a name="min_caps"/><h2>"min_caps" - Ignores capacitors with a capacitance below a certain value</h2>
 <keyword name="min_caps"/>
-<a name="min_caps"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>min_caps(threshold)</tt></li>
 </ul>
 <p>
 See <a href="/about/lvs_ref_netter.xml#min_caps">Netter#min_caps</a> for a description of that function.
 </p>
-<h2>"netter" - Creates a new netter object</h2>
+<a name="netter"/><h2>"netter" - Creates a new netter object</h2>
 <keyword name="netter"/>
-<a name="netter"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>netter</tt></li>
 </ul>
 <p>
 See <a href="/about/lvs_ref_netter.xml">Netter</a> for more details
 </p>
-<h2>"report_lvs" - Specifies an LVS report for output</h2>
+<a name="report_lvs"/><h2>"report_lvs" - Specifies an LVS report for output</h2>
 <keyword name="report_lvs"/>
-<a name="report_lvs"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>report_lvs([ filename [, long ] ])</tt></li>
 </ul>
@@ -121,27 +121,27 @@ extracted netlist.
 </p><p>
 report_lvs is only effective if a comparison step is included.
 </p>
-<h2>"same_circuits" - Establishes an equivalence between the circuits</h2>
+<a name="same_circuits"/><h2>"same_circuits" - Establishes an equivalence between the circuits</h2>
 <keyword name="same_circuits"/>
-<a name="same_circuits"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>same_circuits(circuit_a, circuit_b)</tt></li>
 </ul>
 <p>
 See <a href="/about/lvs_ref_netter.xml#same_circuits">Netter#same_circuits</a> for a description of that function.
 </p>
-<h2>"same_device_classes" - Establishes an equivalence between the device_classes</h2>
+<a name="same_device_classes"/><h2>"same_device_classes" - Establishes an equivalence between the device_classes</h2>
 <keyword name="same_device_classes"/>
-<a name="same_device_classes"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>same_device_classes(class_a, class_b)</tt></li>
 </ul>
 <p>
 See <a href="/about/lvs_ref_netter.xml#same_device_classes">Netter#same_device_classes</a> for a description of that function.
 </p>
-<h2>"same_nets" - Establishes an equivalence between the nets</h2>
+<a name="same_nets"/><h2>"same_nets" - Establishes an equivalence between the nets</h2>
 <keyword name="same_nets"/>
-<a name="same_nets"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>same_nets(circuit, net_a, net_b)</tt></li>
 <li><tt>same_nets(circuit_a, net_a, circuit_b, net_b)</tt></li>
@@ -149,9 +149,9 @@ See <a href="/about/lvs_ref_netter.xml#same_device_classes">Netter#same_device_c
 <p>
 See <a href="/about/lvs_ref_netter.xml#same_nets">Netter#same_nets</a> for a description of that function.
 </p>
-<h2>"schematic" - Reads the reference netlist</h2>
+<a name="schematic"/><h2>"schematic" - Reads the reference netlist</h2>
 <keyword name="schematic"/>
-<a name="schematic"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>schematic(filename)</tt></li>
 <li><tt>schematic(filename, reader)</tt></li>
@@ -160,9 +160,9 @@ See <a href="/about/lvs_ref_netter.xml#same_nets">Netter#same_nets</a> for a des
 <p>
 See <a href="/about/lvs_ref_netter.xml#schematic">Netter#schematic</a> for a description of that function.
 </p>
-<h2>"tolerance" - Specifies compare tolerances for certain device parameters</h2>
+<a name="tolerance"/><h2>"tolerance" - Specifies compare tolerances for certain device parameters</h2>
 <keyword name="tolerance"/>
-<a name="tolerance"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>tolerance(device_class_name, parameter_name, absolute_tolerance [, relative_tolerance])</tt></li>
 <li><tt>tolerance(device_class_name, parameter_name [, :absolute =&gt; absolute_tolerance] [, :relative =&gt; relative_tolerance])</tt></li>
diff --git a/src/lay/lay/doc/about/lvs_ref_netter.xml b/src/lay/lay/doc/about/lvs_ref_netter.xml
index b4a1c1b94..d3a7923e0 100644
--- a/src/lay/lay/doc/about/lvs_ref_netter.xml
+++ b/src/lay/lay/doc/about/lvs_ref_netter.xml
@@ -43,9 +43,9 @@ end
 </pre>
 </p>
 <h2-index/>
-<h2>"align" - Aligns the extracted netlist vs. the schematic</h2>
+<a name="align"/><h2>"align" - Aligns the extracted netlist vs. the schematic</h2>
 <keyword name="align"/>
-<a name="align"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>align</tt></li>
 </ul>
@@ -68,9 +68,9 @@ are other (explicit) ways to flatten circuits.
 Please note that flattening circuits has some side effects such 
 as loss of details in the cross reference and net layout.
 </p>
-<h2>"compare" - Compares the extracted netlist vs. the schematic</h2>
+<a name="compare"/><h2>"compare" - Compares the extracted netlist vs. the schematic</h2>
 <keyword name="compare"/>
-<a name="compare"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>compare</tt></li>
 </ul>
@@ -85,9 +85,9 @@ corresponding circuits: the unpaired circuit will be flattened then.
 This method will return true, if the netlists are equivalent and false
 otherwise.
 </p>
-<h2>"equivalent_pins" - Marks pins as equivalent</h2>
+<a name="equivalent_pins"/><h2>"equivalent_pins" - Marks pins as equivalent</h2>
 <keyword name="equivalent_pins"/>
-<a name="equivalent_pins"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>equivalent_pins(circuit, pin ...)</tt></li>
 </ul>
@@ -110,9 +110,9 @@ If the netlist provides named pins, names can be used instead of numbers.
 Before this method can be used, a schematic netlist needs to be loaded with
 <a href="#schematic">schematic</a>.
 </p>
-<h2>"join_symmetric_nets" - Joins symmetric nets of selected circuits on the extracted netlist</h2>
+<a name="join_symmetric_nets"/><h2>"join_symmetric_nets" - Joins symmetric nets of selected circuits on the extracted netlist</h2>
 <keyword name="join_symmetric_nets"/>
-<a name="join_symmetric_nets"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>join_symmetric_nets(circuit_filter)</tt></li>
 </ul>
@@ -133,9 +133,9 @@ those circuits for which this feature is required.
 For the symmetry detection, the specified constraints (e.g. tolerances,
 device filters etc.) apply.
 </p>
-<h2>"lvs_data" - Gets the internal <class_doc href="LayoutVsSchematic">LayoutVsSchematic</class_doc> object</h2>
+<a name="lvs_data"/><h2>"lvs_data" - Gets the internal <class_doc href="LayoutVsSchematic">LayoutVsSchematic</class_doc> object</h2>
 <keyword name="lvs_data"/>
-<a name="lvs_data"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>lvs_data</tt></li>
 </ul>
@@ -143,9 +143,29 @@ device filters etc.) apply.
 The <class_doc href="LayoutVsSchematic">LayoutVsSchematic</class_doc> object provides access to the internal details of
 the netter object.
 </p>
-<h2>"max_depth" - Configures the maximum search depth for net match deduction</h2>
+<a name="max_branch_complexity"/><h2>"max_branch_complexity" - Configures the maximum branch complexity for ambiguous net matching</h2>
+<keyword name="max_branch_complexity"/>
+<p>Usage:</p>
+<ul>
+<li><tt>max_branch_complexity(n)</tt></li>
+</ul>
+<p>
+The netlist compare algorithm is basically a backtracing algorithm.
+With ambiguous nets, the algorithm picks possible net pairs and
+tries whether they will make a good match. Following the deduction
+path for this nets may lead to further branches if more ambiguous
+nets are encountered. To avoid combinational explosion, the maximum
+branch complexity is limited to the value configured with this 
+function. The default value is 500 which means not more than
+500 combinations are tried for a single seed pair. For networks
+with inherent ambiguity such as decoders, the complexity
+can be increased at the expense of potentially larger runtimes.
+The runtime penality is roughly proportional to the branch
+complexity.
+</p>
+<a name="max_depth"/><h2>"max_depth" - Configures the maximum search depth for net match deduction</h2>
 <keyword name="max_depth"/>
-<a name="max_depth"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>max_depth(n)</tt></li>
 </ul>
@@ -160,9 +180,9 @@ pursues this "deduction path" in greater depth while with
 smaller values, the algorithm prefers picking nets in a random fashion
 as the seeds for this deduction path. The default value is 8. 
 </p>
-<h2>"max_res" - Ignores resistors with a resistance above a certain value</h2>
+<a name="max_res"/><h2>"max_res" - Ignores resistors with a resistance above a certain value</h2>
 <keyword name="max_res"/>
-<a name="max_res"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>max_res(threshold)</tt></li>
 </ul>
@@ -170,9 +190,9 @@ as the seeds for this deduction path. The default value is 8.
 After using this method, the netlist compare will ignore resistor devices
 with a resistance value above the given threshold (in Farad).
 </p>
-<h2>"min_caps" - Ignores capacitors with a capacitance below a certain value</h2>
+<a name="min_caps"/><h2>"min_caps" - Ignores capacitors with a capacitance below a certain value</h2>
 <keyword name="min_caps"/>
-<a name="min_caps"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>min_caps(threshold)</tt></li>
 </ul>
@@ -180,9 +200,9 @@ with a resistance value above the given threshold (in Farad).
 After using this method, the netlist compare will ignore capacitance devices
 with a capacitance values below the given threshold (in Farad).
 </p>
-<h2>"same_circuits" - Establishes an equivalence between the circuits</h2>
+<a name="same_circuits"/><h2>"same_circuits" - Establishes an equivalence between the circuits</h2>
 <keyword name="same_circuits"/>
-<a name="same_circuits"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>same_circuits(circuit_a, circuit_b)</tt></li>
 </ul>
@@ -197,9 +217,9 @@ other circuit is mapped to "nothing", i.e. ignored.
 Before this method can be used, a schematic netlist needs to be loaded with
 <a href="#schematic">schematic</a>.
 </p>
-<h2>"same_device_classes" - Establishes an equivalence between the device classes</h2>
+<a name="same_device_classes"/><h2>"same_device_classes" - Establishes an equivalence between the device classes</h2>
 <keyword name="same_device_classes"/>
-<a name="same_device_classes"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>same_device_classes(class_a, class_b)</tt></li>
 </ul>
@@ -215,9 +235,9 @@ other device class is mapped to "nothing", i.e. ignored.
 Before this method can be used, a schematic netlist needs to be loaded with
 <a href="#schematic">schematic</a>.
 </p>
-<h2>"same_nets" - Establishes an equivalence between the nets</h2>
+<a name="same_nets"/><h2>"same_nets" - Establishes an equivalence between the nets</h2>
 <keyword name="same_nets"/>
-<a name="same_nets"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>same_nets(circuit, net_a, net_b)</tt></li>
 <li><tt>same_nets(circuit_a, net_a, circuit_b, net_b)</tt></li>
@@ -237,9 +257,9 @@ resolve otherwise.
 Before this method can be used, a schematic netlist needs to be loaded with
 <a href="#schematic">schematic</a>.
 </p>
-<h2>"schematic" - Gets, sets or reads the reference netlist</h2>
+<a name="schematic"/><h2>"schematic" - Gets, sets or reads the reference netlist</h2>
 <keyword name="schematic"/>
-<a name="schematic"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>schematic(filename)</tt></li>
 <li><tt>schematic(filename, reader)</tt></li>
@@ -257,9 +277,9 @@ If no reader is provided, Spice format will be assumed. The reader object is a
 Alternatively, a <class_doc href="Netlist">Netlist</class_doc> object can be given which is obtained from any other
 source.
 </p>
-<h2>"tolerance" - Specifies compare tolerances for certain device parameters</h2>
+<a name="tolerance"/><h2>"tolerance" - Specifies compare tolerances for certain device parameters</h2>
 <keyword name="tolerance"/>
-<a name="tolerance"/><p>Usage:</p>
+<p>Usage:</p>
 <ul>
 <li><tt>tolerance(device_class_name, parameter_name, absolute_tolerance [, relative_tolerance])</tt></li>
 <li><tt>tolerance(device_class_name, parameter_name [, :absolute =&gt; absolute_tolerance] [, :relative =&gt; relative_tolerance])</tt></li>
diff --git a/src/lay/lay/doc/manual/lvs_device_extractors.xml b/src/lay/lay/doc/manual/lvs_device_extractors.xml
index 4af511c2a..b6fdbe30a 100644
--- a/src/lay/lay/doc/manual/lvs_device_extractors.xml
+++ b/src/lay/lay/doc/manual/lvs_device_extractors.xml
@@ -37,7 +37,7 @@
 
   <pre>sheet_rho = 0.5
 model_name = "RES"
-extract_devices(resistor(model_name, sheet_rho), { "R" => res_layer, "C" => cap_layer })</pre>
+extract_devices(resistor(model_name, sheet_rho), { "R" => res_layer, "C" => contact_layer })</pre>
 
   <p>
   The plain resistor offers two terminals which it outputs on "tA" and "tB" terminal layers.
@@ -62,6 +62,13 @@ extract_devices(resistor(model_name, sheet_rho), { "R" => res_layer, "C" => cap_
   <img src="/manual/res_ex_tw.png"/>
   </p>
 
+  <p>
+  <b>Note:</b> The resistance computation is based on a simple approximation. It computes the number 
+  of squares by tracing the perimeter of the "R" polygon. The perimeter length is separated 
+  in parts where the perimeter touches the "C" layer and parts where it does not. The number 
+  of squares is computed from the non-touching length divided by the touching length.
+  </p>
+
   <h2>Capacitor extractors (<a href="/about/drc_ref_global.xml#capacitor">capacitor</a> 
       and <a href="/about/drc_ref_global.xml#capacitor_with_bulk">capacitor_with_bulk</a>)</h2>
 
@@ -119,11 +126,6 @@ extract_devices(capacitor(model_name, area_cap), { "P1" => metal1, "P2" => metal
   <img src="/manual/diode_ex_layout.png"/>
   </p>
 
-  <p>
-  The extractor will compute the capacitance from the area of the 
-  overlap and the capacitance per area (F/µm²) value.
-  </p>
-
   <pre>model_name = "DIODE"
 extract_devices(diode(model_name), { "P" => pplus, "N" => nwell })</pre>