diff --git a/aerotow.nas b/aerotow.nas
index 8548f05..1105a85 100644
--- a/aerotow.nas
+++ b/aerotow.nas
@@ -12,11 +12,12 @@
 #
 # Constants
 #
-var addon = addons.getAddon("org.flightgear.addons.Aerotow");
+var ADDON = addons.getAddon("org.flightgear.addons.Aerotow");
+var ADDON_NODE_PATH = ADDON.node.getPath();
 var FILENAME_SCENARIO = "aerotown-addon.xml";
 var FILENAME_FLIGHTPLAN = "aerotown-addon-flightplan.xml";
-var PATH_SCENARIO = addon.storagePath ~ "/" ~ FILENAME_SCENARIO;
-var PATH_FLIGHTPLAN = addon.storagePath ~ "/AI/FlightPlans/" ~ FILENAME_FLIGHTPLAN;
+var PATH_SCENARIO = ADDON.storagePath ~ "/" ~ FILENAME_SCENARIO;
+var PATH_FLIGHTPLAN = ADDON.storagePath ~ "/AI/FlightPlans/" ~ FILENAME_FLIGHTPLAN;
 var SCENARIO_ID = "aerotow_addon";
 var SCENARIO_NAME = "Aerotow Add-on";
 var SCENARIO_DESC = "This scenario starts the towing plane at the airport where the pilot with the glider is located. Use Ctrl-o to hook the plane.";
@@ -30,14 +31,14 @@ var g_fpFileHandler = nil; # Handler for wrire flight plan to file
 var g_coord = nil; # Coordinates for flight plan
 var g_heading = nil; # AI plane heading
 var g_altitude = nil; # AI plane altitude
-var g_listeners = [];
+var g_towListeners = [];
 
 #
 # Initialize thermal module
 #
 var init = func () {
     # Listener for ai-model property triggered when the user select a tow aircraft from add-on menu
-    append(g_listeners, setlistener(addon.node.getPath() ~ "/addon-devel/ai-model", func () {
+    append(g_towListeners, setlistener(ADDON_NODE_PATH ~ "/addon-devel/ai-model", func () {
         startAerotow();
     }));
 }
@@ -46,7 +47,7 @@ var init = func () {
 # Uninitialize thermal module
 #
 var uninit = func () {
-    foreach (var listener; g_listeners) {
+    foreach (var listener; g_towListeners) {
         removelistener(listener);
     }
 }
@@ -172,7 +173,7 @@ var isScenarioAdded = func () {
 # Return name of selected aircraft. Possible values: "Cub", "DR400", "c182".
 #
 var getSelectedAircraft = func () {
-    return getprop(addon.node.getPath() ~ "/addon-devel/ai-model") or "Cub";
+    return getprop(ADDON_NODE_PATH ~ "/addon-devel/ai-model") or "Cub";
 }
 
 #
diff --git a/thermal.nas b/thermal.nas
index 3b18a25..6002aa5 100644
--- a/thermal.nas
+++ b/thermal.nas
@@ -12,7 +12,8 @@
 #
 # Constants
 #
-var addon = addons.getAddon("org.flightgear.addons.Aerotow");
+var ADDON = addons.getAddon("org.flightgear.addons.Aerotow");
+var ADDON_NODE_PATH = ADDON.node.getPath();
 
 #
 # Variables
@@ -23,31 +24,35 @@ var g_thermalListeners = [];
 # Initialize thermal module
 #
 var init = func () {
-    append(g_thermalListeners, setlistener(addon.node.getPath() ~ "/addon-devel/add-thermal/distance-m", func () {
+    # Listener for calculate distance from meters to nautical miles.
+    append(g_thermalListeners, setlistener(ADDON_NODE_PATH ~ "/addon-devel/add-thermal/distance-m", func () {
         setprop(
-            addon.node.getPath() ~ "/addon-devel/add-thermal/distance-nm",
-            getprop(addon.node.getPath() ~ "/addon-devel/add-thermal/distance-m") * globals.M2NM
+            ADDON_NODE_PATH ~ "/addon-devel/add-thermal/distance-nm",
+            getprop(ADDON_NODE_PATH ~ "/addon-devel/add-thermal/distance-m") * globals.M2NM
         );
     }));
 
-    append(g_thermalListeners, setlistener(addon.node.getPath() ~ "/addon-devel/add-thermal/strength-fps", func () {
+    # Listener for calculate strength from ft/s to m/s.
+    append(g_thermalListeners, setlistener(ADDON_NODE_PATH ~ "/addon-devel/add-thermal/strength-fps", func () {
         setprop(
-            addon.node.getPath() ~ "/addon-devel/add-thermal/strength-mps",
-            getprop(addon.node.getPath() ~ "/addon-devel/add-thermal/strength-fps") * globals.FPS2KT * globals.KT2MPS
+            ADDON_NODE_PATH ~ "/addon-devel/add-thermal/strength-mps",
+            getprop(ADDON_NODE_PATH ~ "/addon-devel/add-thermal/strength-fps") * globals.FPS2KT * globals.KT2MPS
         );
     }));
 
-    append(g_thermalListeners, setlistener(addon.node.getPath() ~ "/addon-devel/add-thermal/diameter-ft", func () {
+    # Listener for calculate diameter from ft to m.
+    append(g_thermalListeners, setlistener(ADDON_NODE_PATH ~ "/addon-devel/add-thermal/diameter-ft", func () {
         setprop(
-            addon.node.getPath() ~ "/addon-devel/add-thermal/diameter-m",
-            getprop(addon.node.getPath() ~ "/addon-devel/add-thermal/diameter-ft") * globals.FT2M
+            ADDON_NODE_PATH ~ "/addon-devel/add-thermal/diameter-m",
+            getprop(ADDON_NODE_PATH ~ "/addon-devel/add-thermal/diameter-ft") * globals.FT2M
         );
     }));
 
-    append(g_thermalListeners, setlistener(addon.node.getPath() ~ "/addon-devel/add-thermal/height-msl", func () {
+    # Listener for calculate height from ft to m.
+    append(g_thermalListeners, setlistener(ADDON_NODE_PATH ~ "/addon-devel/add-thermal/height-msl", func () {
         setprop(
-            addon.node.getPath() ~ "/addon-devel/add-thermal/height-msl-m",
-            getprop(addon.node.getPath() ~ "/addon-devel/add-thermal/height-msl") * globals.FT2M
+            ADDON_NODE_PATH ~ "/addon-devel/add-thermal/height-msl-m",
+            getprop(ADDON_NODE_PATH ~ "/addon-devel/add-thermal/height-msl") * globals.FT2M
         );
     }));
 }
@@ -68,12 +73,12 @@ var uninit = func () {
 #
 var add = func () {
     var heading = getprop("/orientation/heading-deg") or 0;
-    var distance = getprop(addon.node.getPath() ~ "/addon-devel/add-thermal/distance-m") or 300;
+    var distance = getprop(ADDON_NODE_PATH ~ "/addon-devel/add-thermal/distance-m") or 300;
 
     var position = geo.aircraft_position();
     position.apply_course_distance(heading, distance);
 
-    # Get random layer from 1 do 4
+    # Get random layer from 1 to 4
     var layer = int(rand() * 4) + 1;
 
     var args = props.Node.new({
@@ -81,9 +86,9 @@ var add = func () {
         "model":        "Models/Weather/altocumulus_layer" ~ layer ~ ".xml",
         "latitude":     position.lat(),
         "longitude":    position.lon(),
-        "strength-fps": getprop(addon.node.getPath() ~ "/addon-devel/add-thermal/strength-fps") or 16.0,
-        "diameter-ft":  getprop(addon.node.getPath() ~ "/addon-devel/add-thermal/diameter-ft") or 4000,
-        "height-msl":   getprop(addon.node.getPath() ~ "/addon-devel/add-thermal/height-msl") or 9000,
+        "strength-fps": getprop(ADDON_NODE_PATH ~ "/addon-devel/add-thermal/strength-fps") or 16.0,
+        "diameter-ft":  getprop(ADDON_NODE_PATH ~ "/addon-devel/add-thermal/diameter-ft") or 4000,
+        "height-msl":   getprop(ADDON_NODE_PATH ~ "/addon-devel/add-thermal/height-msl") or 9000,
         "search-order": "DATA_ONLY"
     });