Added LVS tests, updated doc.

src/lay/lay/doc/manual/lvs_compare.xml

@@ -236,13 +236,7 @@ tolerance("NMOS", "L", :absolute => 0.05, :relative => 0.01)</pre>
 
   <p>
   This has two effects: first, the "L" parameter is written into the Spice output netlist and second, it is compare against
-  the schematic "L" parameter, provided that one is given in the netlist. No compare happens if no "L" parameter is present in the
-  netlist. 
-  </p>
-
-  <p>
-  This behavior is overridden by a "tolerance" or "ignore_parameter" specification for that parameter or if a customer
-  device comparer is installed.
+  the schematic "L" parameter.
   </p>
 
   <p>
@@ -252,8 +246,10 @@ tolerance("NMOS", "L", :absolute => 0.05, :relative => 0.01)</pre>
   <pre>disable_parameter("RES", "R")</pre>
 
   <p>
-  As this will make the parameter to disappear from the netlist, it's often more useful to use "ignore_parameter" instead
-  which has the same effect on the compare step, but will keep it in the netlist.
+  This behavior is overridden by a "tolerance" or "ignore_parameter" specification for that parameter or if a customer
+  device comparer is installed. Netlisting is affected only for the elementary devices (R, C and L) and any Spice writer
+  delegate can choose to ignore the primary flag. A custom device comparer may also ignore this flag. 
+  So after all, enabling or disabling a parameter is not a strong concept but rather a hint.
   </p>
 
   <h2>Pin swapping</h2>

src/lvs/lvs/built-in-macros/_lvs_engine.rb

@@ -191,13 +191,13 @@ module LVS
 
     # %LVS%
     # @name enable_parameter
-    # @brief Specifies whether to enable a parameter from a given device class for the netlisting and default compare
+    # @brief Specifies whether to enable a parameter from a given device class for netlisting and default compare
     # @synopsis enable_parameter(device_class_name, parameter_name)
     # See \Netter#enable_parameter for a description of that function.
 
     # %LVS%
     # @name disable_parameter
-    # @brief Specifies whether to disable a parameter from a given device class for the netlisting and default compare
+    # @brief Specifies whether to disable a parameter from a given device class for netlisting and default compare
     # @synopsis disable_parameter(device_class_name, parameter_name)
     # See \Netter#disable_parameter for a description of that function.
 

src/lvs/lvs/built-in-macros/_lvs_netter.rb

@@ -201,18 +201,24 @@ module LVS
     # @name enable_parameter
     # @brief Indicates whether to enable a specific parameter for a given device
     # @synopsis enable_parameter(device_class_name, parameter_name)
-    # Enabling a parameter has two effects: first the parameter is netlisted and second
-    # the parameter is compared in the netlist compare - provided it is given in the schematic.
-    # Setting a tolerance or using a custom device comparer will override the last rule.
+    # The parameter is made "primary" which enables further applications - e.g. it is netlisted
+    # for some elements which normally would suppress additional parameters and the parameter
+    # is compared in the default device compare scheme during netlist matching.
+    # Enabling a parameter is rather a hint for the system and the effects can be controlled
+    # by other means, so this is not a strong concept. For example, once a \tolerance is 
+    # specified for a parameter, the "primary" flag of the parameter is not considered anymore.
+    # The inverse the this function is \disable_parameter.
 
     # %LVS%
     # @name disable_parameter
     # @brief Indicates whether to disable a specific parameter for a given device
     # @synopsis disable_parameter(device_class_name, parameter_name)
-    # Disabling a parameter has two effects: first the parameter is not netlisted and second
-    # the parameter is compared in the netlist compare - provided it is given in the schematic.
-    # Setting a tolerance or using a custom device comparer will override the last rule.
-    # To disable a parameter for compare only, \ignore_parameter can be used.
+    # Disabling a parameter is the inverse of \enable_parameter. Disabling a parameter will
+    # reset the "primary" flag of the parameter. This has several effects - e.g. the parameter will not be 
+    # used in device compare during netlist matching by default. This is not a strong concept but rather
+    # a hint for the system. Disabling a parameter for netlist compare without side effects
+    # is possible with the \ignore_parameter function. In the same way, \tolerance will enable a parameter for
+    # netlist compare regardless of the "primary" status of the parameter.
 
     [ :enable_parameter, :disable_parameter ].each do |mn|
       eval <<"CODE"

src/lvs/unit_tests/lvsSimpleTests.cc

@@ -261,3 +261,10 @@ TEST(28_BlackBoxDevicesWithBlank)
   run_test (_this, "bbdevices5b", "bbdevices5.gds");
   run_test (_this, "bbdevices6b", "bbdevices6.gds");
 }
+
+TEST(29_DeviceCombineAndTolerances)
+{
+  run_test (_this, "res_combine1", "res_combine.gds");
+  run_test (_this, "res_combine2", "res_combine.gds");
+  run_test (_this, "res_combine3", "res_combine.gds");
+}