diff --git a/doc/function/new_card.txt b/doc/function/new_card.txt
index c61630c8..ff20ea65 100644
--- a/doc/function/new_card.txt
+++ b/doc/function/new_card.txt
@@ -7,7 +7,7 @@ Creates a new [[type:card]] object. The card is not automatically added to a set
 
 The argument is a map from card field names to values, for example @new_card([name: "My Card"])@ creates a card with the name @"My Card"@, and all other fields at their default value.
 
-The map can also contain the following built-in keys: notes, id, linked_card_1 to linked_card_4, linked_relation_1 to linked_relation_4, stylesheet, and styling_data. For styling_data, the value must itself be a map from styling field names to values. Be sure to define a stylesheet before styling_data.
+The map can also contain the following built-in keys: notes, id, linked_card_1 to linked_card_4, linked_relation_1 to linked_relation_4, stylesheet, styling_data, and extra_data. For styling_data and extra_data, the value must itself be a map from field names to values. Be sure to define a stylesheet before these.
 
 NOTE: you should use underscores instead of spaces in field names.
 
diff --git a/src/data/field.cpp b/src/data/field.cpp
index 168b9f04..e0f5c4fc 100644
--- a/src/data/field.cpp
+++ b/src/data/field.cpp
@@ -40,7 +40,6 @@ Field::~Field() {}
 
 void Field::initDependencies(Context& ctx, const Dependency& dep) const {
   sort_script.initDependencies(ctx, dep);
-  import_script.initDependencies(ctx, dep);
 }
 
 IMPLEMENT_REFLECTION(Field) {
diff --git a/src/data/format/clipboard.cpp b/src/data/format/clipboard.cpp
index 7f6a1031..6574cfbc 100644
--- a/src/data/format/clipboard.cpp
+++ b/src/data/format/clipboard.cpp
@@ -62,9 +62,9 @@ wxDataFormat CardsDataObject::format = _("application/x-mse-cards");
 
 CardsDataObject::CardsDataObject(const SetP& set, const vector<CardP>& cards) {
   // set the stylesheet, so when deserializing we know whos style options we are reading
-  bool* has_styling = new bool[cards.size()];
+  vector<bool> has_styling;
   for (size_t i = 0 ; i < cards.size() ; ++i) {
-    has_styling[i] = cards[i]->has_styling && !cards[i]->stylesheet;
+    has_styling.push_back(cards[i]->has_styling && !cards[i]->stylesheet);
     if (has_styling[i]) {
       cards[i]->stylesheet = set->stylesheet;
     }
@@ -78,7 +78,6 @@ CardsDataObject::CardsDataObject(const SetP& set, const vector<CardP>& cards) {
     }
   }
   SetFormat(format);
-  delete [] has_styling;
 }
 
 CardsDataObject::CardsDataObject() {
diff --git a/src/data/keyword.hpp b/src/data/keyword.hpp
index 5888a853..afd5a73a 100644
--- a/src/data/keyword.hpp
+++ b/src/data/keyword.hpp
@@ -91,11 +91,11 @@ public:
   Keyword() : fixed(false), valid(false) {}
   
   String                keyword;    ///< The keyword, only for human use
-  String                rules;    ///< Rules/explanation
-  String                match;    ///< String to match, <atom-param> tags are used for parameters
-  vector<KeywordParamP> parameters;  ///< The types of parameters
-  StringScript          reminder;    ///< Reminder text of the keyword
-  String                mode;      ///< Mode of use, can be used by scripts (only gives the name)
+  String                rules;      ///< Rules/explanation
+  String                match;      ///< String to match, <atom-param> tags are used for parameters
+  vector<KeywordParamP> parameters; ///< The types of parameters
+  StringScript          reminder;   ///< Reminder text of the keyword
+  String                mode;       ///< Mode of use, can be used by scripts (only gives the name)
   /// Regular expression to match and split parameters, automatically generated.
   /** The regex has exactly 2 * parameters.size() + 1 captures (excluding the entire match, caputure 0),
    *  captures 1,3,... capture the plain text of the match string
diff --git a/src/data/pack.cpp b/src/data/pack.cpp
index 18d83daa..0e184a30 100644
--- a/src/data/pack.cpp
+++ b/src/data/pack.cpp
@@ -94,7 +94,7 @@ bool PackType::update(Context& ctx) {
 
 bool PackItem::update(Context& ctx) {
   return amount.update(ctx)
-       | weight.update(ctx);
+      || weight.update(ctx);
 }
 
 
diff --git a/src/data/set.hpp b/src/data/set.hpp
index e6b24af7..0775953f 100644
--- a/src/data/set.hpp
+++ b/src/data/set.hpp
@@ -50,7 +50,7 @@ public:
   /// The values on the fields of the set
   /** The indices should correspond to the set_fields in the Game */
   IndexMap<FieldP, ValueP> data;
-  /// Extra values for specitic stylesheets, indexed by stylesheet name
+  /// Extra values for specific stylesheets, indexed by stylesheet name
   DelayedIndexMaps<FieldP,ValueP> styling_data;
   vector<CardP>            cards;             ///< The cards in the set
   vector<KeywordP>         keywords;          ///< Additional keywords used in this set
diff --git a/src/gui/add_json_window.cpp b/src/gui/add_json_window.cpp
index 414c0c10..c17df358 100644
--- a/src/gui/add_json_window.cpp
+++ b/src/gui/add_json_window.cpp
@@ -19,10 +19,11 @@
 #include <data/stylesheet.hpp>
 #include <data/action/set.hpp>
 #include <gui/add_json_window.hpp>
+#include <script/functions/json.hpp>
 #include <script/functions/construction_helper.hpp>
 #include <wx/statline.h>
-#include <boost/json/src.hpp>
 #include <boost/json.hpp>
+#include <boost/json/src.hpp>
 
 // ----------------------------------------------------------------------------- : AddJSON
 
@@ -63,54 +64,6 @@ AddJSONWindow::AddJSONWindow(Window* parent, const SetP& set, bool sizer)
   }
 }
 
-static ScriptValueP json_to_script(boost::json::value& jv) {
-  if (jv == nullptr) return script_nil;
-  else if (jv.is_null()) return script_nil;
-  else if (jv.is_bool()) return to_script(jv.get_bool());
-  else if (jv.is_double()) return to_script(jv.get_double());
-  else if (jv.is_int64()) {
-    int integer = jv.get_int64();
-    return to_script(integer);
-  }
-  else if (jv.is_uint64()) {
-    int integer = jv.get_uint64();
-    return to_script(integer);
-  }
-  else if (jv.is_string()) {
-    std::string stdstring = boost::json::value_to<std::string>(jv);
-    String wxstring(stdstring.c_str(), wxConvUTF8);
-    return to_script(wxstring);
-  }
-  else if (jv.is_array()) {
-    boost::json::array array = jv.get_array();
-    ScriptCustomCollectionP result = make_intrusive<ScriptCustomCollection>();
-    for (int i = 0; i < array.size(); ++i) {
-      boost::json::value jvalue = array[i];
-      ScriptValueP value = json_to_script(jvalue);
-      result->value.push_back(value);
-    }
-    return result;
-  }
-  else if (jv.is_object()) {
-    boost::json::object object = jv.get_object();
-    ScriptCustomCollectionP result = make_intrusive<ScriptCustomCollection>();
-    for (auto it = object.begin(); it != object.end(); ++it) {
-      boost::json::string_view jview = it->key();
-      std::string_view stdview = std::string_view(jview.data(), jview.size());
-      std::string stdstring = { stdview.begin(), stdview.end() };
-      String key(stdstring.c_str(), wxConvUTF8);
-      boost::json::value jvalue = it->value();
-      ScriptValueP value = json_to_script(jvalue);
-      result->key_value[key] = value;
-    }
-    return result;
-  }
-  else {
-    queue_message(MESSAGE_ERROR, _ERROR_("add card json unknown type"));
-    return script_nil;
-  }
-}
-
 void AddJSONWindow::setJSONType() {
   int sel = json_type->GetSelection();
   if (sel == json_type->GetCount() - 1) { // Custom type
@@ -210,7 +163,7 @@ void AddJSONWindow::onBrowseFiles(wxCommandEvent&) {
     auto& card = card_array[i].as_object();
     for (int h = 0; h < headers_out.size(); ++h) {
       auto& value = card[headers_out[h].ToStdString()];
-      row.push_back(json_to_script(value));
+      row.push_back(json_to_mse(value, set.get()));
     }
     table_out.push_back(row);
   }
diff --git a/src/gui/set/cards_panel.cpp b/src/gui/set/cards_panel.cpp
index 77e59072..5c1d2019 100644
--- a/src/gui/set/cards_panel.cpp
+++ b/src/gui/set/cards_panel.cpp
@@ -102,36 +102,32 @@ CardsPanel::CardsPanel(Window* parent, int id)
 }
 
 void CardsPanel::updateCardCounts() {
-  if (counts) {
-    if (card_list && set) {
-      int selected = card_list->GetSelectedItemCount();
-      int filtered = card_list->GetItemCount();
-      int total = set->cards.size();
+  if (counts && card_list && set) {
+    int selected = card_list->GetSelectedItemCount();
+    int filtered = card_list->GetItemCount();
+    int total = set->cards.size();
 
-      if (
-            selected_cards_count == selected
-        &&  filtered_cards_count == filtered
-        &&  total_cards_count == total
-      ) return;
+    if (
+          selected_cards_count == selected
+      &&  filtered_cards_count == filtered
+      &&  total_cards_count == total
+      &&  !counts->GetLabel().empty()
+    ) return;
 
-      selected_cards_count = selected;
-      filtered_cards_count = filtered;
-      total_cards_count = total;
+    selected_cards_count = selected;
+    filtered_cards_count = filtered;
+    total_cards_count = total;
 
-      if (filtered == total) {
-        counts->SetLabel(_TOOL_2_("card counts 2",
-          wxString::Format(wxT("%i"), selected),
-          wxString::Format(wxT("%i"), total)));
-      }
-      else {
-        counts->SetLabel(_TOOL_3_("card counts 3",
-          wxString::Format(wxT("%i"), selected),
-          wxString::Format(wxT("%i"), filtered),
-          wxString::Format(wxT("%i"), total)));
-      }
-      
-    } else {
-      counts->SetLabel(_(""));
+    if (filtered == total) {
+      counts->SetLabel(_TOOL_2_("card counts 2",
+        wxString::Format(wxT("%i"), selected),
+        wxString::Format(wxT("%i"), total)));
+    }
+    else {
+      counts->SetLabel(_TOOL_3_("card counts 3",
+        wxString::Format(wxT("%i"), selected),
+        wxString::Format(wxT("%i"), filtered),
+        wxString::Format(wxT("%i"), total)));
     }
   }
 }
diff --git a/src/script/functions/basic.cpp b/src/script/functions/basic.cpp
index 7d4f97b2..bd0fc336 100644
--- a/src/script/functions/basic.cpp
+++ b/src/script/functions/basic.cpp
@@ -11,6 +11,8 @@
 #include <util/version.hpp>
 #include <script/functions/functions.hpp>
 #include <script/functions/util.hpp>
+#include <script/functions/construction_helper.hpp>
+#include <script/functions/json.hpp>
 #include <util/tagged_string.hpp>
 #include <util/spec_sort.hpp>
 #include <util/error.hpp>
@@ -21,6 +23,8 @@
 #include <random>
 #include <wx/filename.h>
 #include <wx/stdpaths.h>
+#include <wx/wfstream.h>
+#include <boost/json.hpp>
 
 
 // ----------------------------------------------------------------------------- : Debugging
@@ -257,6 +261,24 @@ SCRIPT_FUNCTION(to_code) {
   SCRIPT_RETURN(input->toCode());
 }
 
+SCRIPT_FUNCTION(to_json) {
+  SCRIPT_PARAM_C(ScriptValueP, input);
+  SCRIPT_PARAM_C(Set*, set);
+  SCRIPT_PARAM_DEFAULT(bool, pretty_print, true);
+  boost::json::value jv = mse_to_json(input, set);
+
+  queue_message(MESSAGE_ERROR, json_pretty_print(jv));
+
+  if (pretty_print) return to_script(json_pretty_print(jv));
+  else              return to_script(json_ugly_print(jv));
+}
+
+SCRIPT_FUNCTION(from_json) {
+  SCRIPT_PARAM_C(ScriptValueP, input);
+  SCRIPT_PARAM_C(Set*, set);
+  return json_to_mse(input, set);
+}
+
 SCRIPT_FUNCTION(type_name) {
   SCRIPT_PARAM_C(ScriptValueP, input);
   SCRIPT_RETURN(input->typeName());
@@ -818,6 +840,8 @@ void init_script_basic_functions(Context& ctx) {
   ctx.setVariable(_("to_color"),             script_to_color);
   ctx.setVariable(_("to_date"),              script_to_date);
   ctx.setVariable(_("to_code"),              script_to_code);
+  ctx.setVariable(_("to_json"),              script_to_json);
+  ctx.setVariable(_("from_json"),            script_from_json);
   ctx.setVariable(_("type_name"),            script_type_name);
   ctx.setVariable(_("make_map"),             script_make_map);
   ctx.setVariable(_("get_card_styling"),     script_get_card_styling);
diff --git a/src/script/functions/construction.cpp b/src/script/functions/construction.cpp
index 75aad5ef..1beddffb 100644
--- a/src/script/functions/construction.cpp
+++ b/src/script/functions/construction.cpp
@@ -37,9 +37,9 @@ SCRIPT_FUNCTION(new_card) {
     if (key == script_nil) continue;
     String key_name = key->toString();
     // check if the given value is for a built-in field
-    if (set_builtin_container(game, new_card, value, key_name, ignore_field_not_found)) continue;
+    if (set_builtin_container(*game, new_card, value, key_name, ignore_field_not_found)) continue;
     // find the field value (container) that corresponds to the given value
-    Value* container = get_container(game, new_card, key_name, ignore_field_not_found);
+    Value* container = get_card_field_container(*game, new_card->data, key_name, ignore_field_not_found);
     if (container == nullptr) continue;
     FieldP field = container->fieldP;
     // if the field has a construction script, set the value and card context variables to be the given value and this card, run script
@@ -59,9 +59,9 @@ SCRIPT_FUNCTION(new_card) {
           if (script_key == script_nil) continue;
           String script_key_name = script_key->toString();
           // check if the script value is for a built-in field
-          if (set_builtin_container(game, new_card, script_value, script_key_name, ignore_field_not_found)) continue;
+          if (set_builtin_container(*game, new_card, script_value, script_key_name, ignore_field_not_found)) continue;
           // find the field value that corresponds to the script value
-          Value* script_container = get_container(game, new_card, script_key_name, ignore_field_not_found);
+          Value* script_container = get_card_field_container(*game, new_card->data, script_key_name, ignore_field_not_found);
           if (script_container == nullptr) continue;
           // set the field value to the script value
           set_container(script_container, script_value, script_key_name);
@@ -94,9 +94,9 @@ SCRIPT_FUNCTION(new_card) {
         if (script_key == script_nil) continue;
         String script_key_name = script_key->toString();
         // check if the script value is for a built-in field
-        if (set_builtin_container(game, new_card, script_value, script_key_name, ignore_field_not_found)) continue;
+        if (set_builtin_container(*game, new_card, script_value, script_key_name, ignore_field_not_found)) continue;
         // find the field value that corresponds to the script value
-        Value* script_container = get_container(game, new_card, script_key_name, ignore_field_not_found);
+        Value* script_container = get_card_field_container(*game, new_card->data, script_key_name, ignore_field_not_found);
         if (script_container == nullptr) continue;
         // set the field value to the script value
         set_container(script_container, script_value, script_key_name);
diff --git a/src/script/functions/construction_helper.hpp b/src/script/functions/construction_helper.hpp
index 7b9f9b33..38c64176 100644
--- a/src/script/functions/construction_helper.hpp
+++ b/src/script/functions/construction_helper.hpp
@@ -4,6 +4,8 @@
 //| License:      GNU General Public License 2 or later (see file COPYING)     |
 //+----------------------------------------------------------------------------+
 
+#pragma once
+
 // ----------------------------------------------------------------------------- : Includes
 
 #include <util/prec.hpp>
@@ -12,33 +14,46 @@
 #include <data/field/package_choice.hpp>
 #include <data/field/color.hpp>
 #include <data/field/image.hpp>
+#include <data/field/symbol.hpp>
 #include <data/action/set.hpp>
 #include <data/game.hpp>
 #include <data/set.hpp>
 #include <data/stylesheet.hpp>
 #include <data/card.hpp>
-#include <util/error.hpp>
 
 // ----------------------------------------------------------------------------- : Helper functions
 
-static Value* get_container(GameP& game, CardP& card, String key_name, bool ignore_field_not_found) {
+inline static Value* get_card_field_container(Game& game, IndexMap<FieldP, ValueP>& map, String& key_name, bool ignore_field_not_found) {
   // find value container to update
-  IndexMap<FieldP, ValueP>::const_iterator value_it = card->data.find(key_name);
-  if (value_it == card->data.end()) {
+  IndexMap<FieldP, ValueP>::const_iterator it = map.find(key_name);
+  if (it == map.end()) {
     // look among alternate names
-    map<String, String>::iterator alt_name_it = game->card_fields_alt_names.find(unified_form(key_name));
-    if (alt_name_it != game->card_fields_alt_names.end()) {
-      value_it = card->data.find(alt_name_it->second);
+    std::map<String, String>::iterator alt_name_it = game.card_fields_alt_names.find(unified_form(key_name));
+    if (alt_name_it != game.card_fields_alt_names.end()) {
+      it = map.find(alt_name_it->second);
     }
   }
-  if (value_it == card->data.end()) {
+  if (it == map.end()) {
     if (ignore_field_not_found) return nullptr;
-    throw ScriptError(_ERROR_1_("no field with name", key_name));
+    throw ScriptError(_ERROR_2_("no field with name", _TYPE_("card"), key_name));
   }
-  return value_it->get();
+  return it->get();
 }
 
-static void set_container(Value* container, ScriptValueP& value, String key_name) {
+inline static Value* get_container(IndexMap<FieldP, ValueP>& map, String& type, String& key_name, bool ignore_field_not_found) {
+  // find value container to update
+  IndexMap<FieldP, ValueP>::const_iterator it = map.find(key_name);
+  if (it == map.end()) {
+    it = map.find(key_name.Lower());
+    if (it == map.end()) {
+      if (ignore_field_not_found) return nullptr;
+      throw ScriptError(_ERROR_2_("no field with name", _TYPE_V_(type), key_name));
+    }
+  }
+  return it->get();
+}
+
+inline static void set_container(Value* container, ScriptValueP& value, String key_name) {
   // set the given value into the container
   if (TextValue* tvalue = dynamic_cast<TextValue*>(container)) {
     tvalue->value = value->toString();
@@ -53,23 +68,36 @@ static void set_container(Value* container, ScriptValueP& value, String key_name
     cvalue->value = value->toColor();
   }
   else if (ImageValue* ivalue = dynamic_cast<ImageValue*>(container)) {
-    wxFileName fname(static_cast<ExternalImage*>(value.get())->toString());
-    ivalue->filename = LocalFileName::fromReadString(fname.GetName(), "");
+    if (ExternalImage* image = dynamic_cast<ExternalImage*>(value.get())) {
+      wxFileName fname(image->toString());
+      ivalue->filename = LocalFileName::fromReadString(fname.GetName(), "");
+    } else if (value->type() == SCRIPT_STRING) {
+      ivalue->filename = LocalFileName::fromReadString(value->toString(), "");
+    } else {
+      throw ScriptError(_ERROR_1_("cant set image value", key_name));
+    }
+  }
+  else if (SymbolValue* svalue = dynamic_cast<SymbolValue*>(container)) {
+    if (value->type() == SCRIPT_STRING) {
+      svalue->filename = LocalFileName::fromReadString(value->toString(), "");
+    } else {
+      throw ScriptError(_ERROR_1_("cant set symbol value", key_name));
+    }
   }
   else {
-    throw ScriptError(_ERROR_1_("can't set value", key_name));
+    throw ScriptError(_ERROR_1_("cant set value", key_name));
   }
 }
 
-static bool set_builtin_container(GameP& game, CardP& card, ScriptValueP& value, String key_name, bool ignore_field_not_found) {
+inline static bool set_builtin_container(const Game& game, CardP& card, ScriptValueP& value, String key_name, bool ignore_field_not_found) {
   // check if the given value is for a built-in field, if found set it and return true
   key_name = unified_form(key_name);
   if (key_name == _("notes") || key_name == _("note")) {
     card->notes = value->toString();
     return true;
   } else if (key_name == _("style") || key_name == _("stylesheet") || key_name == _("template")) {
-    if (trim(value->toString()) != wxEmptyString) {
-      card->stylesheet = StyleSheet::byGameAndName(*game, value->toString());
+    if (!trim(value->toString()).empty()) {
+      card->stylesheet = StyleSheet::byGameAndName(game, value->toString());
       if (card->stylesheet) card->styling_data.init(card->stylesheet->styling_fields);
     }
     return true;
@@ -110,35 +138,34 @@ static bool set_builtin_container(GameP& game, CardP& card, ScriptValueP& value,
   //  card->linked_relation_4 = value->toString();
   //  return true;
   //}
-  else if (key_name == _("styling_data")   || key_name == _("style_data")   || key_name == _("stylesheet_data")   || key_name == _("template_data") || key_name == _("styling")
-        || key_name == _("styling_fields") || key_name == _("style_fields") || key_name == _("stylesheet_fields") || key_name == _("template_fields")) {
+  else if          (key_name == _("styling_data")   || key_name == _("style_data")   || key_name == _("stylesheet_data")   || key_name == _("template_data") || key_name == _("styling")
+                 || key_name == _("styling_fields") || key_name == _("style_fields") || key_name == _("stylesheet_fields") || key_name == _("template_fields")
+                 || key_name == _("extra_data")     || key_name == _("extra_fields") || key_name == _("extra_card_data")   || key_name == _("extra_card_fields")) {
+    bool is_extra = key_name == _("extra_data")     || key_name == _("extra_fields") || key_name == _("extra_card_data")   || key_name == _("extra_card_fields");
+    String type = is_extra ? _("extra") : _("styling");
     if (value->type() != SCRIPT_COLLECTION) {
-      throw ScriptError(_ERROR_("styling data not map"));
+      throw ScriptError(_ERROR_1_("styling data not map", type));
     }
-    ScriptValueP value_it = value->makeIterator();
-    ScriptValueP value_key;
-    while (ScriptValueP value_value = value_it->next(&value_key)) {
-      assert(value_key);
-      if (value_key == script_nil) continue;
-      String value_key_name = value_key->toString();
-      IndexMap<FieldP, ValueP>::const_iterator style_it = card->styling_data.find(value_key_name);
-      if (style_it == card->styling_data.end()) {
-        style_it = card->styling_data.find(value_key_name.Lower());
-        if (style_it == card->styling_data.end()) {
-          if (!ignore_field_not_found) throw ScriptError(_ERROR_1_("no style field with name", value_key_name));
-          continue;
-        }
-      }
-      Value* value_container = style_it->get();
-      set_container(value_container, value_value, value_key_name);
-      card->has_styling = true;
+    if (!card->stylesheet) {
+      throw ScriptError(_ERROR_1_("styling data without stylesheet", type));
+    }
+    IndexMap<FieldP, ValueP>& data = is_extra ? card->extraDataFor(*card->stylesheet) : card->styling_data;
+    ScriptValueP it = value->makeIterator();
+    ScriptValueP key;
+    while (ScriptValueP value = it->next(&key)) {
+      assert(key);
+      if (key == script_nil) continue;
+      String key_name = key->toString();
+      Value* container = get_container(data, type, key_name, ignore_field_not_found);
+      set_container(container, value, key_name);
+      if (!is_extra) card->has_styling = true;
     }
     return true;
   }
   return false;
 }
 
-static bool check_table_headers(GameP& game, std::vector<String>& headers, const String& file_extension, String& missing_fields_out) {
+inline static bool check_table_headers(GameP& game, std::vector<String>& headers, const String& file_extension, String& missing_fields_out) {
   if (headers.empty()) {
     queue_message(MESSAGE_ERROR, _("Empty headers given"));
     return false;
@@ -176,7 +203,7 @@ static bool check_table_headers(GameP& game, std::vector<String>& headers, const
   return true;
 }
 
-static bool cards_from_table(SetP& set, vector<String>& headers, std::vector<std::vector<ScriptValueP>>& table, bool ignore_field_not_found, const String& file_extension, vector<CardP>& cards_out) {
+inline static bool cards_from_table(SetP& set, vector<String>& headers, std::vector<std::vector<ScriptValueP>>& table, bool ignore_field_not_found, const String& file_extension, vector<CardP>& cards_out) {
   // ensure table is square
   int count = headers.size();
   for (int y = 0; y < table.size(); ++y) {
@@ -212,5 +239,3 @@ static bool cards_from_table(SetP& set, vector<String>& headers, std::vector<std
   if (ctx_ignore) ctx.setVariable("ignore_field_not_found", ctx_ignore);
   return true;
 }
-
-
diff --git a/src/script/functions/json.hpp b/src/script/functions/json.hpp
new file mode 100644
index 00000000..52b07ed1
--- /dev/null
+++ b/src/script/functions/json.hpp
@@ -0,0 +1,596 @@
+//+----------------------------------------------------------------------------+
+//| Description:  Magic Set Editor - Program to make Magic (tm) cards          |
+//| Copyright:    (C) Twan van Laarhoven and the other MSE developers          |
+//| License:      GNU General Public License 2 or later (see file COPYING)     |
+//+----------------------------------------------------------------------------+
+
+#pragma once
+
+// ----------------------------------------------------------------------------- : Includes
+
+#include <util/prec.hpp>
+#include <data/set.hpp>
+#include <data/card.hpp>
+#include <data/pack.hpp>
+#include <data/format/clipboard.hpp>
+#include <script/functions/construction_helper.hpp>
+#include <boost/json.hpp>
+#include <sstream>
+#include <wx/sstream.h>
+
+
+// All this isn't great, but it will do for now. Idealy you would create JsonWriter and JsonReader classes
+// that inherit from Writer and Reader, and just have a switch to go from normal mode to JSON mode...
+
+
+// ----------------------------------------------------------------------------- : JSON to String
+
+inline static void pretty_print(std::ostream& os, boost::json::value const& jv, std::string* indent = nullptr)
+{
+  std::string indent_;
+  if(! indent)
+    indent = &indent_;
+  switch(jv.kind())
+  {
+  case boost::json::kind::object:
+  {
+    os << "{\n";
+    indent->append(4, ' ');
+    auto const& obj = jv.get_object();
+    if(! obj.empty())
+    {
+      auto it = obj.begin();
+      for(;;)
+      {
+        os << *indent << boost::json::serialize(it->key()) << " : ";
+        pretty_print(os, it->value(), indent);
+        if(++it == obj.end())
+          break;
+        os << ",\n";
+      }
+    }
+    os << "\n";
+    indent->resize(indent->size() - 4);
+    os << *indent << "}";
+    break;
+  }
+
+  case boost::json::kind::array:
+  {
+    os << "[\n";
+    indent->append(4, ' ');
+    auto const& arr = jv.get_array();
+    if(! arr.empty())
+    {
+      auto it = arr.begin();
+      for(;;)
+      {
+        os << *indent;
+        pretty_print( os, *it, indent);
+        if(++it == arr.end())
+          break;
+        os << ",\n";
+      }
+    }
+    os << "\n";
+    indent->resize(indent->size() - 4);
+    os << *indent << "]";
+    break;
+  }
+
+  case boost::json::kind::string:
+  {
+    os << boost::json::serialize(jv.get_string());
+    break;
+  }
+
+  case boost::json::kind::uint64:
+  case boost::json::kind::int64:
+  case boost::json::kind::double_:
+    os << jv;
+    break;
+
+  case boost::json::kind::bool_:
+    if(jv.get_bool())
+      os << "true";
+    else
+      os << "false";
+    break;
+
+  case boost::json::kind::null:
+    os << "null";
+    break;
+  }
+
+  if(indent->empty())
+    os << "\n";
+}
+
+inline static String json_pretty_print(boost::json::value const& jv, std::string* indent = nullptr) {
+  std::ostringstream stream;
+  pretty_print(stream, jv, indent);
+  String string = wxString(stream.str().c_str());
+  return string;
+}
+
+inline static String json_ugly_print(boost::json::value const& jv) {
+  String string = wxString(boost::json::serialize(jv).c_str());
+  return string;
+}
+
+// ----------------------------------------------------------------------------- : JSON to MSE
+
+inline static ScriptValueP json_to_mse(boost::json::value& jv, Set* set);
+
+template <typename T>
+static void read(T& out, boost::json::object& jv, const char value_name[]) {
+  if (!jv.contains(value_name)) return;
+  else {
+    wxStringInputStream stream = {_("")};
+    Reader reader(stream, nullptr, _(""));
+    reader.setValue(wxString(jv[value_name].as_string().c_str()));
+    reader.handle(out);
+  }
+}
+
+// templates don't work with enums? are you kidding me with this language?
+static void read(PackSelectType& out, boost::json::object& jv, const char value_name[]) {
+  if (!jv.contains(value_name)) return;
+  else {
+    wxStringInputStream stream = {_("")};
+    Reader reader(stream, nullptr, _(""));
+    reader.setValue(wxString(jv[value_name].as_string().c_str()));
+    reader.handle(out);
+  }
+}
+
+inline static PackItemP json_to_mse_pack_item(boost::json::object& jv) {
+  PackItemP pack_item = make_intrusive<PackItem>();
+  read(pack_item->name,   jv, "name");
+  read(pack_item->amount, jv, "amount");
+  read(pack_item->weight, jv, "weight");
+  return pack_item;
+}
+
+inline static PackTypeP json_to_mse_pack_type(boost::json::object& jv) {
+  PackTypeP pack_type = make_intrusive<PackType>();
+  read(pack_type->name,       jv, "name");
+  read(pack_type->enabled,    jv, "enabled");
+  read(pack_type->selectable, jv, "selectable");
+  read(pack_type->summary,    jv, "summary");
+  read(pack_type->select,     jv, "select");
+  if (jv.contains("items") && jv["items"].is_array()) {
+    boost::json::array pack_itemsv = jv["items"].as_array();
+    for (int i = 0; i < pack_itemsv.size(); i++) {
+      boost::json::object pack_itemv = pack_itemsv[i].as_object();
+      pack_type->items.emplace_back(json_to_mse_pack_item(pack_itemv));
+    }
+  }
+  return pack_type;
+}
+
+inline static KeywordP json_to_mse_keyword(boost::json::object& jv) {
+  KeywordP keyword = make_intrusive<Keyword>();
+  read(keyword->keyword,  jv, "keyword");
+  read(keyword->match,    jv, "match");
+  read(keyword->reminder, jv, "reminder");
+  read(keyword->rules,    jv, "rules");
+  read(keyword->mode,     jv, "mode");
+  return keyword;
+}
+
+inline static CardP json_to_mse_card(boost::json::object& jv, Set* set) {
+  CardP card = make_intrusive<Card>(*set->game);
+  read(card->time_created,                     jv, "time_created");
+  read(card->time_modified,                    jv, "time_modified");
+  read(card->notes,                            jv, "notes");
+  //read(card->uid,                              jv, "uid");
+  //read(card->linked_card_1,                    jv, "linked_card_1");
+  //read(card->linked_card_2,                    jv, "linked_card_2");
+  //read(card->linked_card_3,                    jv, "linked_card_3");
+  //read(card->linked_card_4,                    jv, "linked_card_4");
+  //read(card->linked_relation_1,                jv, "linked_relation_1");
+  //read(card->linked_relation_2,                jv, "linked_relation_2");
+  //read(card->linked_relation_3,                jv, "linked_relation_3");
+  //read(card->linked_relation_4,                jv, "linked_relation_4");
+  // card fields
+  if (jv.contains("data") && jv["data"].is_object()) {
+    boost::json::object datav = jv["data"].as_object();
+    for (auto it = datav.begin(); it != datav.end(); ++it) {
+      String key_name = wxString(it->key_c_str());
+      Value* container = get_card_field_container(*set->game, card->data, key_name, false);
+      ScriptValueP value = json_to_mse(it->value(), set);
+      set_container(container, value, key_name);
+    }
+  }
+  // stylesheet
+  if (jv.contains("stylesheet")) card->stylesheet = StyleSheet::byGameAndName(*set->game, wxString(jv["stylesheet"].as_string().c_str()));
+  if (card->stylesheet) {
+    // styling fields
+    card->styling_data.init(card->stylesheet->styling_fields);
+    if (jv.contains("styling_data") && jv["styling_data"].is_object()) {
+      boost::json::object datav = jv["styling_data"].as_object();
+      for (auto it = datav.begin(); it != datav.end(); ++it) {
+        String key_name = wxString(it->key_c_str());
+        Value* container = get_container(card->styling_data, wxString("styling"), key_name, false);
+        ScriptValueP value = json_to_mse(it->value(), set);
+        set_container(container, value, key_name);
+        card->has_styling = true;
+      }
+    }
+    // extra card fields
+    if (jv.contains("extra_data") && jv["extra_data"].is_object()) {
+      boost::json::object datav = jv["extra_data"].as_object();
+      for (auto it = datav.begin(); it != datav.end(); ++it) {
+        StyleSheetP& stylesheet = StyleSheet::byGameAndName(*set->game, it->key_c_str());
+        if (!stylesheet) continue;
+        IndexMap<FieldP, ValueP>& stylesheet_data = card->extraDataFor(*stylesheet);
+        boost::json::object stylesheet_datav = it->value().as_object();
+        for (auto stylesheet_it = stylesheet_datav.begin(); stylesheet_it != stylesheet_datav.end(); ++stylesheet_it) {
+          String key_name = wxString(stylesheet_it->key_c_str());
+          Value* container = get_container(stylesheet_data, wxString("extra card"), key_name, false);
+          ScriptValueP value = json_to_mse(stylesheet_it->value(), set);
+          set_container(container, value, key_name);
+        }
+      }
+    }
+  }
+  return card;
+}
+
+inline static SetP json_to_mse_set(boost::json::object& jv) {
+  if (!jv.contains("game")) {
+    throw ScriptError(_ERROR_("json set without game"));
+  }
+  if (!jv.contains("stylesheet")) {
+    throw ScriptError(_ERROR_("json set without stylesheet"));
+  }
+  GameP& game = Game::byName(wxString(jv["game"].as_string().c_str()));
+  StyleSheetP& stylesheet = StyleSheet::byGameAndName(*game, wxString(jv["stylesheet"].as_string().c_str()));
+  SetP& set = make_intrusive<Set>(stylesheet);
+  // set fields
+  if (jv.contains("set_info") && jv["set_info"].is_object()) {
+    boost::json::object datav = jv["set_info"].as_object();
+    for (auto it = datav.begin(); it != datav.end(); ++it) {
+      String key_name = wxString(it->key_c_str());
+      Value* container = get_container(set->data, wxString("set"), key_name, false);
+      ScriptValueP value = json_to_mse(it->value(), set.get());
+      set_container(container, value, key_name);
+    }
+  }
+  // styling
+  if (jv.contains("styling") && jv["styling"].is_object()) {
+    boost::json::object datav = jv["styling"].as_object();
+    for (auto it = datav.begin(); it != datav.end(); ++it) {
+      StyleSheetP& stylesheet = StyleSheet::byGameAndName(*set->game, it->key_c_str());
+      if (!stylesheet) continue;
+      IndexMap<FieldP, ValueP>& stylesheet_data = set->stylingDataFor(*stylesheet);
+      boost::json::object stylesheet_datav = it->value().as_object();
+      for (auto stylesheet_it = stylesheet_datav.begin(); stylesheet_it != stylesheet_datav.end(); ++stylesheet_it) {
+        String key_name = wxString(stylesheet_it->key_c_str());
+        Value* container = get_container(stylesheet_data, wxString("styling"), key_name, false);
+        ScriptValueP value = json_to_mse(stylesheet_it->value(), set.get());
+        set_container(container, value, key_name);
+      }
+    }
+  }
+  // cards
+  if (jv.contains("cards") && jv["cards"].is_array()) {
+    boost::json::array cardsv = jv["cards"].as_array();
+    for (int i = 0; i < cardsv.size(); i++) {
+      boost::json::object cardv = cardsv[i].as_object();
+      set->cards.emplace_back(json_to_mse_card(cardv, set.get()));
+    }
+  }
+  // keywords
+  if (jv.contains("keywords") && jv["keywords"].is_array()) {
+    boost::json::array keywordsv = jv["keywords"].as_array();
+    for (int i = 0; i < keywordsv.size(); i++) {
+      boost::json::object keywordv = keywordsv[i].as_object();
+      set->keywords.emplace_back(json_to_mse_keyword(keywordv));
+    }
+  }
+  // pack types
+  if (jv.contains("pack_types") && jv["pack_types"].is_array()) {
+    boost::json::array pack_typesv = jv["pack_types"].as_array();
+    for (int i = 0; i < pack_typesv.size(); i++) {
+      boost::json::object pack_typev = pack_typesv[i].as_object();
+      set->pack_types.emplace_back(json_to_mse_pack_type(pack_typev));
+    }
+  }
+  return set;
+}
+
+inline static ScriptValueP json_to_mse(boost::json::value& jv, Set* set) {
+  if (jv == nullptr) return script_nil;
+  else if (jv.is_null()) return script_nil;
+  else if (jv.is_bool()) return to_script(jv.get_bool());
+  else if (jv.is_double()) return to_script(jv.get_double());
+  else if (jv.is_int64()) {
+    int integer = jv.get_int64();
+    return to_script(integer);
+  }
+  else if (jv.is_uint64()) {
+    int integer = jv.get_uint64();
+    return to_script(integer);
+  }
+  else if (jv.is_string()) {
+    std::string stdstring = boost::json::value_to<std::string>(jv);
+    String wxstring(stdstring.c_str(), wxConvUTF8);
+    return to_script(wxstring);
+  }
+  else if (jv.is_array()) {
+    boost::json::array array = jv.get_array();
+    ScriptCustomCollectionP result = make_intrusive<ScriptCustomCollection>();
+    for (int i = 0; i < array.size(); ++i) {
+      boost::json::value jvalue = array[i];
+      ScriptValueP value = json_to_mse(jvalue, set);
+      result->value.push_back(value);
+    }
+    return result;
+  }
+  else if (jv.is_object()) {
+    boost::json::object object = jv.get_object();
+    if (object.contains("mse_object_type")) {
+      boost::json::string mse_object_type = object["mse_object_type"].as_string();
+      if (mse_object_type == "set")       return make_intrusive<ScriptObject<SetP>>     (json_to_mse_set(object));
+      if (mse_object_type == "card")      return make_intrusive<ScriptObject<CardP>>    (json_to_mse_card(object, set));
+      if (mse_object_type == "keyword")   return make_intrusive<ScriptObject<KeywordP>> (json_to_mse_keyword(object));
+      if (mse_object_type == "pack_type") return make_intrusive<ScriptObject<PackTypeP>>(json_to_mse_pack_type(object));
+      if (mse_object_type == "pack_item") return make_intrusive<ScriptObject<PackItemP>>(json_to_mse_pack_item(object));
+      queue_message(MESSAGE_ERROR, _ERROR_("json unknown type") + _("(") + wxString(mse_object_type.c_str()) + _(")"));
+      return script_nil;
+    }
+    ScriptCustomCollectionP result = make_intrusive<ScriptCustomCollection>();
+    for (auto it = object.begin(); it != object.end(); ++it) {
+      boost::json::string_view jview = it->key();
+      std::string_view stdview = std::string_view(jview.data(), jview.size());
+      std::string stdstring = { stdview.begin(), stdview.end() };
+      String key(stdstring.c_str(), wxConvUTF8);
+      boost::json::value jvalue = it->value();
+      ScriptValueP value = json_to_mse(jvalue, set);
+      result->key_value[key] = value;
+    }
+    return result;
+  }
+  else {
+    queue_message(MESSAGE_ERROR, _ERROR_("json unknown type"));
+    return script_nil;
+  }
+}
+inline static ScriptValueP json_to_mse(String& string, Set* set) {
+  try {
+    boost::system::error_code ec;
+    boost::json::parse_options options;
+    options.allow_invalid_utf8 = true;
+    boost::json::value jv = boost::json::parse(string.ToStdString(), ec, {}, options);
+    if(ec) queue_message(MESSAGE_ERROR, _ERROR_("json cant parse") + _("\n\n") + ec.message());
+    return json_to_mse(jv, set);
+  }
+  catch (...) {
+    queue_message(MESSAGE_ERROR, _ERROR_("json cant parse"));
+    return script_nil;
+  }
+}
+inline static ScriptValueP json_to_mse(ScriptValueP& sv, Set* set) {
+  try {
+    String string = sv->toString();
+    return json_to_mse(string, set);
+  }
+  catch (...) {
+    queue_message(MESSAGE_ERROR, _ERROR_("json cant convert"));
+    return script_nil;
+  }
+}
+
+// ----------------------------------------------------------------------------- : MSE to JSON
+
+template <typename T>
+static void write(boost::json::object& out, const String& name, T& value) {
+  wxStringOutputStream stream;
+  Writer writer(stream);
+  writer.indentation = -1000;
+  writer.handle(name, value);
+  String string = stream.GetString();
+  if (!string.empty()) {
+    if (string.StartsWith(name + ":")) string = string.substr(name.length() + 1).Trim(false);
+    if (string.EndsWith("\n")) string = string.substr(0, string.length() - 1);
+    out.emplace(name.ToStdString(), string);
+  }
+}
+
+static void write(boost::json::object& out, const String& name, IndexMap<FieldP, ValueP>& map) {
+  boost::json::object indexmapv;
+  for (IndexMap<FieldP, ValueP>::iterator it = map.begin(); it != map.end(); ++it) {
+    write(indexmapv, (*it)->fieldP->name, *it);
+  }
+  if (!indexmapv.empty()) out.emplace(name.ToStdString(), indexmapv);
+}
+
+static void write(boost::json::object& out, const String& name, DelayedIndexMaps<FieldP,ValueP>& map) {
+  boost::json::object delayedindexmapv;
+  for (auto it = map.data.begin() ; it != map.data.end() ; ++it) {
+    write(delayedindexmapv, it->first, it->second->read_data);
+  }
+  if (!delayedindexmapv.empty()) out.emplace(name.ToStdString(), delayedindexmapv);
+}
+
+inline static boost::json::object mse_to_json(PackItemP& item) {
+  boost::json::object itemv;
+  itemv.emplace("mse_object_type", "pack_item");
+  write(itemv, "name",   item->name);
+  write(itemv, "amount", item->amount);
+  write(itemv, "weight", item->weight);
+  return itemv;
+}
+
+inline static boost::json::object mse_to_json(PackTypeP& pack) {
+  boost::json::object packv;
+  packv.emplace("mse_object_type", "pack_type");
+  write(packv, "name",       pack->name);
+  write(packv, "enabled",    pack->enabled);
+  write(packv, "selectable", pack->selectable);
+  write(packv, "summary",    pack->summary);
+  write(packv, "select",     pack->select);
+  write(packv, "filter",     pack->filter);
+  boost::json::array itemsv;
+  for (auto item : pack->items) {
+    itemsv.emplace_back(mse_to_json(item));
+  }
+  packv.emplace("items", itemsv);
+  return packv;
+}
+
+inline static boost::json::object mse_to_json(KeywordP& keyword) {
+  boost::json::object keywordv;
+  keywordv.emplace("mse_object_type", "keyword");
+  write(keywordv, "keyword",  keyword->keyword);
+  write(keywordv, "match",    keyword->match);
+  write(keywordv, "reminder", keyword->reminder);
+  write(keywordv, "rules",    keyword->rules);
+  write(keywordv, "mode",     keyword->mode);
+  return keywordv;
+}
+
+inline static boost::json::object mse_to_json(CardP& card, Set* set) {
+  boost::json::object cardv;
+  cardv.emplace("mse_object_type", "card");
+  // built-in values
+  write(cardv, "time_created",      card->time_created);
+  write(cardv, "time_modified",     card->time_modified);
+  write(cardv, "notes",             card->notes);
+  //write(cardv, "uid",               card->uid);
+  //write(cardv, "linked_card_1",     card->linked_card_1);
+  //write(cardv, "linked_card_2",     card->linked_card_2);
+  //write(cardv, "linked_card_3",     card->linked_card_3);
+  //write(cardv, "linked_card_4",     card->linked_card_4);
+  //write(cardv, "linked_relation_1", card->linked_relation_1);
+  //write(cardv, "linked_relation_2", card->linked_relation_2);
+  //write(cardv, "linked_relation_3", card->linked_relation_3);
+  //write(cardv, "linked_relation_4", card->linked_relation_4);
+  // card fields
+  write(cardv, "data",              card->data);
+  // stylesheet
+  bool change_stylesheet = set && !card->stylesheet;
+  if (change_stylesheet) {
+    card->stylesheet = set->stylesheet;
+  }
+  if (card->stylesheet) {
+    write(cardv, "stylesheet",         card->stylesheet);
+    write(cardv, "stylesheet_version", card->stylesheet->version);
+    // extra card fields
+    write(cardv, "extra_data",         card->extra_data);
+  }
+  // style
+  write(cardv, "has_styling",       card->has_styling);
+  if (card->has_styling) {
+    write(cardv, "styling_data",       card->styling_data);
+  }
+  // restore stylesheet
+  if (change_stylesheet) {
+    card->stylesheet = StyleSheetP();
+  }
+  // done
+  return cardv;
+}
+
+inline static boost::json::object mse_to_json(Set* set) {
+  boost::json::object setv;
+  setv.emplace("mse_object_type",    "set");
+  // built-in values
+  write(setv, "mse_version",        set->fileVersion());
+  write(setv, "game",               set->game);
+  write(setv, "game_version",       set->game->version);
+  write(setv, "stylesheet",         set->stylesheet);
+  write(setv, "stylesheet_version", set->stylesheet->version);
+  // set fields
+  write(setv, "set_info",           set->data);
+  // styling
+  write(setv, "styling",            set->styling_data);
+  // cards
+  boost::json::array cardsv;
+  for (auto card : set->cards) {
+    cardsv.emplace_back(mse_to_json(card, set));
+  }
+  setv.emplace("cards", cardsv);
+  // keywords
+  boost::json::array keywordsv;
+  for (auto keyword : set->keywords) {
+    keywordsv.emplace_back(mse_to_json(keyword));
+  }
+  if (!keywordsv.empty()) setv.emplace("keywords", keywordsv);
+  // pack types
+  boost::json::array pack_typesv;
+  for (auto pack_type : set->pack_types) {
+    pack_typesv.emplace_back(mse_to_json(pack_type));
+  }
+  if (!pack_typesv.empty()) setv.emplace("pack_types", pack_typesv);
+  // done
+  return setv;
+}
+
+inline static boost::json::value mse_to_json(ScriptValueP& sv, Set* set) {
+  ScriptType type = sv->type();
+  // special types
+  if (ScriptObject<PackItemP>* i = dynamic_cast<ScriptObject<PackItemP>*>(sv.get())) return mse_to_json(i->getValue());
+  if (ScriptObject<PackTypeP>* t = dynamic_cast<ScriptObject<PackTypeP>*>(sv.get())) return mse_to_json(t->getValue());
+  if (ScriptObject<KeywordP>*  k = dynamic_cast<ScriptObject<KeywordP>*> (sv.get())) return mse_to_json(k->getValue());
+  if (ScriptObject<CardP>*     c = dynamic_cast<ScriptObject<CardP>*>    (sv.get())) return mse_to_json(c->getValue(), set);
+  if (ScriptObject<SetP>*      z = dynamic_cast<ScriptObject<SetP>*>     (sv.get())) return mse_to_json(z->getValue().get());
+  if (ScriptObject<Set*>*      s = dynamic_cast<ScriptObject<Set*>*>     (sv.get())) return mse_to_json(s->getValue());
+
+  // primitive types
+  if (type == SCRIPT_NIL)      return boost::json::value(nullptr);
+  if (type == SCRIPT_INT)      return boost::json::value(sv->toInt());
+  if (type == SCRIPT_DOUBLE)   return boost::json::value(sv->toDouble());
+  if (type == SCRIPT_BOOL)     return boost::json::value(sv->toBool());
+  if (type == SCRIPT_STRING)   return boost::json::value(sv->toString());
+  if (type == SCRIPT_REGEX)    return boost::json::value(sv->toString());
+  if (type == SCRIPT_COLOR)    return boost::json::value(format_color(sv->toColor()));
+  if (type == SCRIPT_DATETIME) return boost::json::value(sv->toDateTime().FormatISOCombined(' '));
+  if (type == SCRIPT_COLLECTION) {
+    ScriptCustomCollection* custom = dynamic_cast<ScriptCustomCollection*>(sv.get());
+    if (custom) {
+      if (custom->value.size() > 0) {
+        boost::json::array array;
+        for (int i = 0; i < custom->value.size(); i++) {
+          array.emplace_back(mse_to_json(custom->value[i], set));
+        }
+        return array;
+      } else if (custom->key_value.size() > 0) {
+        boost::json::object object;
+        map<String, ScriptValueP>::iterator it;
+        for (it = custom->key_value.begin(); it != custom->key_value.end(); it++) {
+          object.emplace(it->first.ToStdString(), mse_to_json(it->second, set));
+        }
+        return object;
+      }
+    } else {
+      ScriptConcatCollection* concat = dynamic_cast<ScriptConcatCollection*>(sv.get());
+      if (concat) {
+        boost::json::value a = mse_to_json(concat->getA(), set);
+        boost::json::value b = mse_to_json(concat->getB(), set);
+        if (a.is_array() && b.is_array()) {
+          boost::json::array array_a = a.get_array();
+          boost::json::array array_b = b.get_array();
+          for (int i = 0; i < array_b.size(); i++) {
+            array_a.emplace_back(array_b[i]);
+          }
+          return array_a;
+        } else if (a.is_object() && b.is_object()) {
+          boost::json::object object_a = a.get_object();
+          boost::json::object object_b = b.get_object();
+          for (auto it = object_b.begin(); it != object_b.end(); ++it) {
+            object_a.emplace(it->key(), it->value());
+          }
+          return object_a;
+        } else {
+          queue_message(MESSAGE_ERROR, _ERROR_("json cant concat"));
+          return boost::json::value(nullptr);
+        }
+      }
+    }
+  }
+  queue_message(MESSAGE_ERROR, _ERROR_1_("json unknown script type", sv->typeName()));
+  return boost::json::value(nullptr);
+}
diff --git a/src/script/to_value.hpp b/src/script/to_value.hpp
index a52a563a..21ea2c26 100644
--- a/src/script/to_value.hpp
+++ b/src/script/to_value.hpp
@@ -223,7 +223,10 @@ public:
   inline ScriptConcatCollection(ScriptValueP a, ScriptValueP b) : a(a), b(b) {}
   ScriptValueP getMember(const String& name) const override;
   ScriptValueP getIndex(int index) const override;
-  ScriptValueP makeIterator() const override;
+  ScriptValueP makeIterator() const override;
+  ScriptValueP getA() { return a; }
+  ScriptValueP getB() { return b; }
+
   int itemCount() const override { return a->itemCount() + b->itemCount(); }
   /// Collections can be compared by comparing pointers
   CompareWhat compareAs(String&, void const*& compare_ptr) const override {
diff --git a/src/util/index_map.hpp b/src/util/index_map.hpp
index 600ed68e..5798d996 100644
--- a/src/util/index_map.hpp
+++ b/src/util/index_map.hpp
@@ -149,8 +149,8 @@ public:
   IndexMap<Key,Value>& get(const String& name, const vector<Key>& init_with);
   /// Clear the delayed index map
   void clear();
-private:
   map<String, intrusive_ptr<DelayedIndexMapsData<Key,Value>>> data;
+private:
   friend class Reader;
   friend class Writer;
   friend class GetDefaultMember;
diff --git a/src/util/io/reader.hpp b/src/util/io/reader.hpp
index 51e0876e..155b5e90 100644
--- a/src/util/io/reader.hpp
+++ b/src/util/io/reader.hpp
@@ -118,6 +118,9 @@ public:
   inline Packaged* getPackage() const { return package; }
   
   String addLocale(String);
+
+  /// Set the value that will be returned by the next getValue() call (may mess up the state of the reader)
+  inline void setValue(const String& value) { state = UNHANDLED; previous_value = value; };
 
 private:
   // --------------------------------------------------- : Data
diff --git a/src/util/io/writer.cpp b/src/util/io/writer.cpp
index e984b34e..901bf90b 100644
--- a/src/util/io/writer.cpp
+++ b/src/util/io/writer.cpp
@@ -16,6 +16,12 @@
 using boost::tribool;
 
 // ----------------------------------------------------------------------------- : Writer
+
+Writer::Writer(OutputStream& output)
+  : indentation(0)
+  , output(output)
+  , stream(output, wxEOL_UNIX, wxMBConvUTF8())
+{}
 
 Writer::Writer(OutputStream& output, Version file_app_version)
   : indentation(0)
diff --git a/src/util/io/writer.hpp b/src/util/io/writer.hpp
index 7a223637..dfc8a7e5 100644
--- a/src/util/io/writer.hpp
+++ b/src/util/io/writer.hpp
@@ -25,8 +25,9 @@ DECLARE_POINTER_TYPE(StyleSheet);
 class Writer {
 public:
   /// Construct a writer that writes to the given output stream
+  Writer(OutputStream& output);
   Writer(OutputStream& output, Version file_app_version);
-  
+
   /// Tell the reflection code we are not reading
   static constexpr bool isReading = false;
   static constexpr bool isWriting = true;
@@ -72,11 +73,11 @@ public:
   // special behaviour
   void handle(const GameP&);
   void handle(const StyleSheetP&);
-  
-private:
-  // --------------------------------------------------- : Data
+  
   /// Indentation of the current block
   int indentation;
+private:
+  // --------------------------------------------------- : Data
   /// Blocks opened to which nothing has been written
   vector<const Char*> pending_opened;
   
diff --git a/src/util/locale.hpp b/src/util/locale.hpp
index 93476aff..d6e97503 100644
--- a/src/util/locale.hpp
+++ b/src/util/locale.hpp
@@ -76,6 +76,7 @@ String tr(const String&, const String& subcat, const String& key, DefaultLocaleF
 #define _TITLE_(s)   tr(LOCALE_CAT_TITLE,     _(s))
 /// A localized string for type names in scripts
 #define _TYPE_(s)    tr(LOCALE_CAT_TYPE,      _(s))
+#define _TYPE_V_(s)  tr(LOCALE_CAT_TYPE,        s )
 /// A localized string for action names
 #define _ACTION_(s)  tr(LOCALE_CAT_ACTION,    _(s))
 /// A localized string for error messages