diff --git a/src/libse/Common/Settings.cs b/src/libse/Common/Settings.cs
index a8f118b96..6a85915c6 100644
--- a/src/libse/Common/Settings.cs
+++ b/src/libse/Common/Settings.cs
@@ -833,6 +833,7 @@ namespace Nikse.SubtitleEdit.Core.Common
         public string TimedTextItunesTimeCodeFormat { get; set; }
         public string TimedTextItunesStyleAttribute { get; set; }
         public string TimedTextImsc11TimeCodeFormat { get; set; }
+        public string TimedTextImsc11FileExtension { get; set; }
 
 
         public int FcpFontSize { get; set; }
@@ -921,6 +922,7 @@ $HorzAlign          =   Center
             TimedTextItunesTimeCodeFormat = "Frames";
             TimedTextItunesStyleAttribute = "tts:fontStyle";
             TimedTextImsc11TimeCodeFormat = "hh:mm:ss.ms";
+            TimedTextImsc11FileExtension = ".xml";
 
             FcpFontSize = 18;
             FcpFontName = "Lucida Grande";
@@ -7523,6 +7525,18 @@ $HorzAlign          =   Center
                     settings.SubtitleSettings.TimedTextItunesStyleAttribute = subNode.InnerText;
                 }
 
+                subNode = node.SelectSingleNode("TimedTextImsc11TimeCodeFormat");
+                if (subNode != null)
+                {
+                    settings.SubtitleSettings.TimedTextImsc11TimeCodeFormat = subNode.InnerText;
+                }
+
+                subNode = node.SelectSingleNode("TimedTextImsc11FileExtension");
+                if (subNode != null)
+                {
+                    settings.SubtitleSettings.TimedTextImsc11FileExtension = subNode.InnerText;
+                }
+
                 subNode = node.SelectSingleNode("FcpFontSize");
                 if (subNode != null)
                 {
@@ -12219,6 +12233,8 @@ $HorzAlign          =   Center
                 textWriter.WriteElementString("TimedTextItunesBottomExtent", settings.SubtitleSettings.TimedTextItunesBottomExtent);
                 textWriter.WriteElementString("TimedTextItunesTimeCodeFormat", settings.SubtitleSettings.TimedTextItunesTimeCodeFormat);
                 textWriter.WriteElementString("TimedTextItunesStyleAttribute", settings.SubtitleSettings.TimedTextItunesStyleAttribute);
+                textWriter.WriteElementString("TimedTextImsc11TimeCodeFormat", settings.SubtitleSettings.TimedTextImsc11TimeCodeFormat);
+                textWriter.WriteElementString("TimedTextImsc11FileExtension", settings.SubtitleSettings.TimedTextImsc11FileExtension);
                 textWriter.WriteElementString("FcpFontSize", settings.SubtitleSettings.FcpFontSize.ToString(CultureInfo.InvariantCulture));
                 textWriter.WriteElementString("FcpFontName", settings.SubtitleSettings.FcpFontName);
                 textWriter.WriteElementString("Cavena890StartOfMessage", settings.SubtitleSettings.Cavena890StartOfMessage);
diff --git a/src/libse/SubtitleFormats/TimedTextImsc11.cs b/src/libse/SubtitleFormats/TimedTextImsc11.cs
index c2980f0cf..4b7d65253 100644
--- a/src/libse/SubtitleFormats/TimedTextImsc11.cs
+++ b/src/libse/SubtitleFormats/TimedTextImsc11.cs
@@ -12,7 +12,6 @@ namespace Nikse.SubtitleEdit.Core.SubtitleFormats
     /// </summary>
     public class TimedTextImsc11 : SubtitleFormat
     {
-        public override string Extension => ".xml";
         public override string Name => "Timed Text IMSC 1.1";
 
         private static string GetXmlStructure()
@@ -46,6 +45,8 @@ namespace Nikse.SubtitleEdit.Core.SubtitleFormats
 ".Replace('\'', '"');
         }
 
+        public override string Extension => Configuration.Settings.SubtitleSettings.TimedTextImsc11FileExtension;
+
         public override bool IsMine(List<string> lines, string fileName)
         {
             if (fileName != null && !(fileName.EndsWith(Extension, StringComparison.OrdinalIgnoreCase) || fileName.EndsWith(".xml", StringComparison.OrdinalIgnoreCase)))
diff --git a/src/ui/Forms/TimedTextPropertiesIms11.Designer.cs b/src/ui/Forms/TimedTextPropertiesIms11.Designer.cs
index b08d2e0c1..90dd51ce0 100644
--- a/src/ui/Forms/TimedTextPropertiesIms11.Designer.cs
+++ b/src/ui/Forms/TimedTextPropertiesIms11.Designer.cs
@@ -1,6 +1,6 @@
 namespace Nikse.SubtitleEdit.Forms
 {
-    partial class TimedTextPropertiesIms11
+    sealed partial class TimedTextPropertiesIms11
     {
         /// <summary>
         /// Required designer variable.
diff --git a/src/ui/Forms/TimedTextPropertiesIms11.cs b/src/ui/Forms/TimedTextPropertiesIms11.cs
index b7fd66b23..ffc05dba4 100644
--- a/src/ui/Forms/TimedTextPropertiesIms11.cs
+++ b/src/ui/Forms/TimedTextPropertiesIms11.cs
@@ -8,7 +8,7 @@ using System.Xml;
 
 namespace Nikse.SubtitleEdit.Forms
 {
-    public partial class TimedTextPropertiesIms11 : PositionAndSizeForm
+    public sealed partial class TimedTextPropertiesIms11 : PositionAndSizeForm
     {
         private readonly Subtitle _subtitle;
         private readonly XmlDocument _xml;
@@ -21,6 +21,8 @@ namespace Nikse.SubtitleEdit.Forms
             UiUtil.FixFonts(this);
             Application.DoEvents();
 
+            Text = string.Format(LanguageSettings.Current.Main.Menu.File.FormatXProperties, new TimedTextImsc11().Name);
+
             _subtitle = subtitle;
             var notAvailable = "[" + LanguageSettings.Current.General.NotAvailable + "]";
             comboBoxDropMode.Items[0] = notAvailable;
@@ -126,7 +128,7 @@ namespace Nikse.SubtitleEdit.Forms
                 }
             }
 
-            var ext = Configuration.Settings.SubtitleSettings.TimedText10FileExtension;
+            var ext = Configuration.Settings.SubtitleSettings.TimedTextImsc11FileExtension;
             comboBoxFileExtensions.SelectedIndex = 0;
             for (var index = 0; index < comboBoxFileExtensions.Items.Count; index++)
             {
@@ -313,7 +315,7 @@ namespace Nikse.SubtitleEdit.Forms
 
             Configuration.Settings.SubtitleSettings.TimedTextImsc11TimeCodeFormat = comboBoxTimeCodeFormat.SelectedItem.ToString();
 
-            var currentTimedTextExt = Configuration.Settings.SubtitleSettings.TimedText10FileExtension;
+            var currentTimedTextExt = Configuration.Settings.SubtitleSettings.TimedTextImsc11FileExtension;
             var newTimedTextExt = comboBoxFileExtensions.SelectedItem.ToString();
             if (currentTimedTextExt != newTimedTextExt)
             {
@@ -325,7 +327,7 @@ namespace Nikse.SubtitleEdit.Forms
                     Configuration.Settings.General.FavoriteSubtitleFormats = favoriteFormats.Replace(currentTimedTextWithExt, newTimedTextWithExt);
                 }
 
-                Configuration.Settings.SubtitleSettings.TimedText10FileExtension = newTimedTextExt;
+                Configuration.Settings.SubtitleSettings.TimedTextImsc11FileExtension = newTimedTextExt;
             }
 
             DialogResult = DialogResult.OK;