diff --git a/pk3DS/3DS/SMDH.cs b/pk3DS/3DS/SMDH.cs
new file mode 100644
index 0000000..f933596
--- /dev/null
+++ b/pk3DS/3DS/SMDH.cs
@@ -0,0 +1,188 @@
+using System;
+using System.Drawing;
+using System.IO;
+using System.Text;
+
+namespace CTR
+{
+    // System Menu Data Header
+    class SMDH
+    {
+        public uint Magic;
+        public ushort Version;
+        public ushort Reserved2;
+        public ApplicationInfo[] AppInfo = new ApplicationInfo[16];
+        public ApplicationSettings AppSettings;
+        public ulong Reserved8;
+        public SmallIcon SmallIcon;
+        public LargeIcon LargeIcon;
+
+        public SMDH(byte[] data)
+        {
+            Read(new BinaryReader(new MemoryStream(data)));
+        }
+        public SMDH(string path)
+        {
+            Read(new BinaryReader(File.OpenRead(path)));
+        }
+        public void Read(BinaryReader br)
+        {
+            // Check to see if the first 4 bytes (magic) is valid.
+            if (br.BaseStream.Length != 0x36C0 || (Magic = br.ReadUInt32()) != 0x48444D53)
+                return; // Abort
+
+            Version = br.ReadUInt16();
+            Reserved2 = br.ReadUInt16();
+
+            for (int i = 0; i < 16; i++)
+                AppInfo[i] = new ApplicationInfo(br);
+
+            AppSettings = new ApplicationSettings(br);
+            Reserved8 = br.ReadUInt64();
+            SmallIcon = new SmallIcon(br);
+            LargeIcon = new LargeIcon(br);
+        }
+        public byte[] Write()
+        {
+            using (var ms = new MemoryStream())
+            using (var bw = new BinaryWriter(ms))
+            {
+                bw.Write(Magic);
+                bw.Write(Version);
+                bw.Write(Reserved2);
+                for (int i = 0; i < 16; i++) AppInfo[i].Write(bw);
+                AppSettings.Write(bw);
+                bw.Write(Reserved8);
+                SmallIcon.Write(bw);
+                LargeIcon.Write(bw);
+                return ms.ToArray();   
+            }
+        }
+    }
+
+    // Thanks to Gericom for EveryFileExplorer's SMDH.cs as a basis for the object code (and AppSettings enumeration)
+    class ApplicationInfo
+    {
+        public String ShortDescription; //0x80
+        public String LongDescription; //0x100
+        public String Publisher; //0x80
+        public ApplicationInfo(BinaryReader br)
+        {
+            ShortDescription = Encoding.Unicode.GetString(br.ReadBytes(0x80)).TrimEnd('\0');
+            LongDescription = Encoding.Unicode.GetString(br.ReadBytes(0x100)).TrimEnd('\0');
+            Publisher = Encoding.Unicode.GetString(br.ReadBytes(0x80)).TrimEnd('\0');
+        }
+        public void Write(BinaryWriter bw)
+        {
+            bw.Write(Encoding.Unicode.GetBytes(ShortDescription.PadRight(64, '\0')));
+            bw.Write(Encoding.Unicode.GetBytes(LongDescription.PadRight(64, '\0')));
+            bw.Write(Encoding.Unicode.GetBytes(Publisher.PadRight(64, '\0')));
+        }
+    }
+
+    class ApplicationSettings
+    {
+        public byte[] GameRatings; //0x10
+        public RegionLockoutFlags RegionLockout;
+        public UInt32 MatchMakerID;
+        public UInt64 MatchMakerBITID;
+        public AppSettingsFlags Flags;
+        public UInt16 EULAVersion;
+        public UInt16 Reserved;
+        public Single AnimationDefaultFrame;
+        public UInt32 StreetPassID;
+        
+        public enum RegionLockoutFlags : uint
+        {
+            Japan = 0x01,
+            NorthAmerica = 0x02,
+            Europe = 0x04,
+            Australia = 0x08,
+            China = 0x10,
+            Korea = 0x20,
+            Taiwan = 0x40
+        }
+        public enum AppSettingsFlags : uint
+        {
+            Visible = 1,
+            AutoBoot = 2,
+            Allow3D = 4,
+            ReqAcceptEULA = 8,
+            AutoSaveOnExit = 16,
+            UsesExtendedBanner = 32,
+            ReqRegionGameRating = 64,
+            UsesSaveData = 128,
+            RecordUsage = 256,
+            DisableSDSaveBackup = 512
+        }
+        public ApplicationSettings(BinaryReader br)
+        {
+            GameRatings = br.ReadBytes(0x10);
+            RegionLockout = (RegionLockoutFlags)br.ReadUInt32();
+            MatchMakerID = br.ReadUInt32();
+            MatchMakerBITID = br.ReadUInt64();
+            Flags = (AppSettingsFlags)br.ReadUInt32();
+            EULAVersion = br.ReadUInt16();
+            Reserved = br.ReadUInt16();
+            AnimationDefaultFrame = br.ReadSingle();
+            StreetPassID = br.ReadUInt32();
+        }
+        public void Write(BinaryWriter bw)
+        {
+            bw.Write(GameRatings, 0, 0x10);
+            bw.Write((uint)RegionLockout);
+            bw.Write(MatchMakerID);
+            bw.Write(MatchMakerBITID);
+            bw.Write((uint)Flags);
+            bw.Write(EULAVersion);
+            bw.Write(Reserved);
+            bw.Write(AnimationDefaultFrame);
+            bw.Write(StreetPassID);
+        }
+    }
+
+    class SmallIcon // 24x24
+    {
+        public Bitmap Icon;
+        public byte[] Bytes;
+        public SmallIcon(BinaryReader br)
+        {
+            Bytes = br.ReadBytes(0x480);
+            Icon = BCLIM.getIMG(24, 24, Bytes, 0x5);
+        }
+        public void Write(BinaryWriter bw)
+        {
+            bw.Write(Bytes);
+        }
+        public bool ChangeIcon(Bitmap img)
+        {
+            if (img.Width != Icon.Width || img.Height != Icon.Height) return false;
+            Icon = img;
+            Bytes = BCLIM.getPixelData(Icon, 0x5);
+            return true;
+        }
+    }
+
+    class LargeIcon // 48x48
+    {
+        public Bitmap Icon;
+        public byte[] Bytes;
+        public LargeIcon(BinaryReader br)
+        {
+            Bytes = br.ReadBytes(0x2000);
+            Icon = BCLIM.getIMG(48, 48, Bytes, 0x5);
+        }
+        public void Write(BinaryWriter bw)
+        {
+            bw.Write(Bytes);
+            Bytes = BCLIM.getPixelData(Icon, 0x5);
+        }
+        public bool ChangeIcon(Bitmap img)
+        {
+            if (img.Width != Icon.Width || img.Height != Icon.Height) return false;
+            Icon = img;
+            Bytes = BCLIM.getPixelData(Icon, 0x5);
+            return true;
+        }
+    }
+}
diff --git a/pk3DS/pk3DS.csproj b/pk3DS/pk3DS.csproj
index c732edb..2d1b3b6 100644
--- a/pk3DS/pk3DS.csproj
+++ b/pk3DS/pk3DS.csproj
@@ -54,6 +54,7 @@
     <Compile Include="3DS\DARC.cs" />
     <Compile Include="3DS\ETC1.cs" />
     <Compile Include="3DS\Exheader.cs" />
+    <Compile Include="3DS\SMDH.cs" />
     <Compile Include="3DS\LZSS.cs" />
     <Compile Include="3DS\mini.cs" />
     <Compile Include="3DS\NCCH.cs" />