diff --git a/PortableExecutable/MenuHeader.cs b/PortableExecutable/MenuHeader.cs
index 9a7b7fb..b58f17a 100644
--- a/PortableExecutable/MenuHeader.cs
+++ b/PortableExecutable/MenuHeader.cs
@@ -3,23 +3,10 @@
 namespace SabreTools.Models.PortableExecutable
 {
     /// <summary>
-    /// Contains version information for the menu resource. The structure definition provided
-    /// here is for explanation only; it is not present in any standard header file.
+    /// Common base class for menu item types
     /// </summary>
     /// <see href="https://learn.microsoft.com/en-us/windows/win32/menurc/menuheader"/>
+    /// <see href="https://learn.microsoft.com/en-us/windows/win32/menurc/menuex-template-header"/>
     [StructLayout(LayoutKind.Sequential)]
-    public sealed class MenuHeader
-    {
-        /// <summary>
-        /// The version number of the menu template. This member must be equal to zero to indicate
-        /// that this is an RT_MENU created with a standard menu template.
-        /// </summary>
-        public ushort Version;
-
-        /// <summary>
-        /// The size of the menu template header. This value is zero for menus you create with a
-        /// standard menu template.
-        /// </summary>
-        public ushort HeaderSize;
-    }
+    public abstract class MenuHeader { }
 }
diff --git a/PortableExecutable/MenuHeaderExtended.cs b/PortableExecutable/MenuHeaderExtended.cs
index 9fbdc25..a0bc8fc 100644
--- a/PortableExecutable/MenuHeaderExtended.cs
+++ b/PortableExecutable/MenuHeaderExtended.cs
@@ -8,7 +8,7 @@ namespace SabreTools.Models.PortableExecutable
     /// </summary>
     /// <see href="https://learn.microsoft.com/en-us/windows/win32/menurc/menuex-template-header"/>
     [StructLayout(LayoutKind.Sequential)]
-    public sealed class MenuHeaderExtended
+    public sealed class MenuHeaderExtended : MenuHeader
     {
         /// <summary>
         /// The template version number. This member must be 1 for extended menu templates.
diff --git a/PortableExecutable/MenuItem.cs b/PortableExecutable/MenuItem.cs
index 847d5a5..74853e9 100644
--- a/PortableExecutable/MenuItem.cs
+++ b/PortableExecutable/MenuItem.cs
@@ -1,9 +1,12 @@
-namespace SabreTools.Models.PortableExecutable
+using System.Runtime.InteropServices;
+
+namespace SabreTools.Models.PortableExecutable
 {
     /// <summary>
     /// Common base class for menu item types
     /// </summary>
     /// <see href="https://learn.microsoft.com/en-us/windows/win32/menurc/normalmenuitem"/>
     /// <see href="https://learn.microsoft.com/en-us/windows/win32/menurc/popupmenuitem"/>
+    [StructLayout(LayoutKind.Sequential)]
     public abstract class MenuItem { }
 }
diff --git a/PortableExecutable/MenuResource.cs b/PortableExecutable/MenuResource.cs
index cfa3083..9412a83 100644
--- a/PortableExecutable/MenuResource.cs
+++ b/PortableExecutable/MenuResource.cs
@@ -9,32 +9,14 @@
     /// <see href="https://learn.microsoft.com/en-us/windows/win32/menurc/resource-file-formats"/>
     public sealed class MenuResource
     {
-        #region Menu header
-
         /// <summary>
         /// Menu header structure
         /// </summary>
         public MenuHeader? MenuHeader { get; set; }
 
-        /// <summary>
-        /// Menu extended header structure
-        /// </summary>
-        public MenuHeaderExtended? ExtendedMenuHeader { get; set; }
-
-        #endregion
-
-        #region Menu items
-
         /// <summary>
         /// Menu items
         /// </summary>
         public MenuItem?[]? MenuItems { get; set; }
-
-        /// <summary>
-        /// Extended menu items
-        /// </summary>
-        public MenuItemExtended?[]? ExtendedMenuItems { get; set; }
-
-        #endregion
     }
 }
diff --git a/PortableExecutable/NormalMenuHeader.cs b/PortableExecutable/NormalMenuHeader.cs
new file mode 100644
index 0000000..af7b8c4
--- /dev/null
+++ b/PortableExecutable/NormalMenuHeader.cs
@@ -0,0 +1,25 @@
+using System.Runtime.InteropServices;
+
+namespace SabreTools.Models.PortableExecutable
+{
+    /// <summary>
+    /// Contains version information for the menu resource. The structure definition provided
+    /// here is for explanation only; it is not present in any standard header file.
+    /// </summary>
+    /// <see href="https://learn.microsoft.com/en-us/windows/win32/menurc/menuheader"/>
+    [StructLayout(LayoutKind.Sequential)]
+    public sealed class NormalMenuHeader: MenuHeader
+    {
+        /// <summary>
+        /// The version number of the menu template. This member must be equal to zero to indicate
+        /// that this is an RT_MENU created with a standard menu template.
+        /// </summary>
+        public ushort Version;
+
+        /// <summary>
+        /// The size of the menu template header. This value is zero for menus you create with a
+        /// standard menu template.
+        /// </summary>
+        public ushort HeaderSize;
+    }
+}