diff --git a/src/db/db/dbLayoutToNetlistFormatDefs.h b/src/db/db/dbLayoutToNetlistFormatDefs.h
index 6c7f4f3fe..bea7dbd60 100644
--- a/src/db/db/dbLayoutToNetlistFormatDefs.h
+++ b/src/db/db/dbLayoutToNetlistFormatDefs.h
@@ -79,7 +79,10 @@ namespace db
  *    circuit(<name> [circuit-def]) - circuit (cell) [short key: X]
  *
  *  [class]:
- *    class(<name> <template> [template-def])  - a device class definition (template: RES,CAP,...) [short key: K]
+ *    class(<name> <template> <full-specs>? [template-def])  - a device class definition (template: RES,CAP,...) [short key: K]
+ *                                    "fill_specs" is an optional value (0 or 1), indicating that all parameters and terminals
+ *                                    are listed. For "1", the reader will remove all specs from the template before rebuilding
+ *                                    them.
  *
  *  [device]:
  *    device(<name> <class> [device-abstract-terminal|any]*)
@@ -158,8 +161,8 @@ namespace db
  *    [template-param|template-terminal|any]*
  *
  *  [template-param]:
- *    param(<name> <primary>? <default-value>*)    - defines a template parameter [short key: E]
- *                                    ('primary' is a value: 0 or 1)
+ *    param(<name> <primary> <default-value>)    - defines a template parameter [short key: E]
+ *                                    ('primary' is a value: 0 or 1, 'default_value' is a float)
  *
  *  [template-terminal]:
  *    terminal(<name>)              - defines a terminal [short key: T]
diff --git a/src/db/db/dbLayoutToNetlistReader.cc b/src/db/db/dbLayoutToNetlistReader.cc
index ac18e9bf9..43b3850bd 100644
--- a/src/db/db/dbLayoutToNetlistReader.cc
+++ b/src/db/db/dbLayoutToNetlistReader.cc
@@ -391,6 +391,9 @@ void LayoutToNetlistStandardReader::read_netlist (db::Netlist *netlist, db::Layo
       read_word_or_quoted (class_name);
       read_word_or_quoted (templ_name);
 
+      int full_specs = 0;
+      try_read_int (full_specs);
+
       if (netlist->device_class_by_name (class_name) != 0) {
         throw tl::Exception (tl::to_string (tr ("Duplicate definition of device class: ")) + class_name);
       }
@@ -407,6 +410,13 @@ void LayoutToNetlistStandardReader::read_netlist (db::Netlist *netlist, db::Layo
         dc = dct->create ();
       }
 
+      //  start with tabula rasa on "full specs"
+      if (full_specs != 0) {
+        dc->clear_equivalent_terminal_ids ();
+        dc->clear_parameter_definitions ();
+        dc->clear_terminal_definitions ();
+      }
+
       dc->set_name (class_name);
       netlist->add_device_class (dc);
 
diff --git a/src/db/db/dbLayoutToNetlistWriter.cc b/src/db/db/dbLayoutToNetlistWriter.cc
index df2499492..092e998bb 100644
--- a/src/db/db/dbLayoutToNetlistWriter.cc
+++ b/src/db/db/dbLayoutToNetlistWriter.cc
@@ -294,11 +294,29 @@ void std_writer_impl<Keys>::write_device_class (TokenizedOutput &stream, const d
   TokenizedOutput out (stream, Keys::class_key);
   out << tl::to_word_or_quoted_string (cls->name ()) << tl::to_word_or_quoted_string (temp_name);
 
+  //  we need to issue all specs if some are deleted
+  bool full_specs = false;
+
+  const std::vector<DeviceParameterDefinition> &pd_temp = temp_class->parameter_definitions ();
+  for (auto p = pd_temp.begin (); p != pd_temp.end () && ! full_specs; ++p) {
+    full_specs = ! cls->has_parameter_with_name (p->name ());
+  }
+
+  const std::vector<DeviceTerminalDefinition> &td_temp = temp_class->terminal_definitions ();
+  for (auto t = td_temp.begin (); t != td_temp.end () && ! full_specs; ++t) {
+    full_specs = ! cls->has_terminal_with_name (t->name ());
+  }
+
+  //  new token: indicates that all specs will be listed
+  if (full_specs) {
+    out << tl::to_string (1);
+  }
+
   bool any_def = false;
 
   const std::vector<DeviceParameterDefinition> &pd = cls->parameter_definitions ();
-  for (std::vector<DeviceParameterDefinition>::const_iterator p = pd.begin (); p != pd.end (); ++p) {
-    if (! temp_class->has_parameter_with_name (p->name ()) || !same_parameter (*p, *temp_class->parameter_definition (temp_class->parameter_id_for_name (p->name ())))) {
+  for (auto p = pd.begin (); p != pd.end (); ++p) {
+    if (full_specs || ! temp_class->has_parameter_with_name (p->name ()) || !same_parameter (*p, *temp_class->parameter_definition (temp_class->parameter_id_for_name (p->name ())))) {
       if (! any_def) {
         out << endl;
       }
@@ -308,8 +326,8 @@ void std_writer_impl<Keys>::write_device_class (TokenizedOutput &stream, const d
   }
 
   const std::vector<DeviceTerminalDefinition> &td = cls->terminal_definitions ();
-  for (std::vector<DeviceTerminalDefinition>::const_iterator t = td.begin (); t != td.end (); ++t) {
-    if (! temp_class->has_terminal_with_name (t->name ())) {
+  for (auto t = td.begin (); t != td.end (); ++t) {
+    if (full_specs || ! temp_class->has_terminal_with_name (t->name ())) {
       if (! any_def) {
         out << endl;
       }