ShortcutLib 1.0.6

ShortcutLib

A zero-dependency .NET library for creating, opening, and editing Windows Shell Link (.lnk) shortcut files in memory.

Features

• Create shortcuts to local files, folders, network shares, and printers
• Open and parse existing .lnk files back into structured options
• Edit existing shortcuts by modifying properties and re-serializing
• Environment variable support (e.g. %windir%\notepad.exe)
• Custom icon, arguments, working directory, and description
• Window style control (normal, maximized, minimized)
• Run as Administrator support
• Hotkey assignment (key + modifier combinations)
• Argument padding to hide command-line arguments in shortcut properties
• Unicode string data support
• Custom file timestamps (creation, access, write)
• Target file size metadata
• Relative path support
• LinkInfo structure (local volume info and network share info)
• Extra data blocks: Console, ConsoleFE, Darwin (MSI), Shim, IconEnvironment, KnownFolder, Tracker, PropertyStore, SpecialFolder, VistaAndAboveIDList
• Unknown extra data block preservation (round-trips unrecognized blocks)
• All 27 LinkFlags from the MS-SHLLINK spec (AllowLinkToLink, ForceNoLinkTrack, etc.)
• FileAttributes enum (ReadOnly, Hidden, System, Encrypted, etc.)
• Network path enhancements (DeviceName, NetworkProviderType)
• LinkInfo Unicode support (0x24 header) for non-ASCII paths, volume labels, and share names
• PropertyStoreBuilder for typed AppUserModelID, ToastActivatorCLSID, PreventPinning, and 30+ additional properties
• PropertyStoreReader for parsing/deserializing property store binary data back into typed entries
• 10 VT types: VT_LPWSTR, VT_BOOL, VT_UI4, VT_CLSID, VT_I2, VT_I4, VT_UI2, VT_I8, VT_UI8, VT_FILETIME, VT_BLOB, VT_LPSTR
• Arbitrary named property support in PropertyStoreBuilder (string, bool, int, uint, DateTime, blob, etc.)
• WinXHasher for computing WinX Power User Menu hashes
• DarwinDescriptor for decoding MSI advertised shortcut descriptors (product/component GUIDs, feature ID)
• TrackerData forensic extraction (MAC address, timestamp from Version 1 UUIDs)
• Named constants: DriveTypes, CsidlFolderIds, VirtualKeys, ConsoleFillAttributes, ConsoleFontFamilies, ShimLayerNames
• ShortcutSanitizer for stripping privacy-sensitive metadata (machine name, MAC address, unknown blocks, etc.)
• Overlay data (post-terminal block data) preservation
• Returns raw byte[] — no COM interop or Windows Shell dependency
• Targets .NET 10

Installation

Add a reference to the ShortcutLib project or install the NuGet package:

dotnet add package ShortcutLib

Usage

Creating Shortcuts

using ShortcutLib;

// Unicode strings with timestamps and file metadata
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Windows\notepad.exe",
    Arguments = "readme.txt",
    Description = "Notepad shortcut",
    WorkingDirectory = @"C:\Windows",
    UseUnicode = true,
    CreationTime = new DateTime(2024, 1, 15, 12, 0, 0, DateTimeKind.Utc),
    AccessTime = DateTime.UtcNow,
    WriteTime = DateTime.UtcNow,
    FileSize = 193536
});

// Shortcut with relative path
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Projects\MyApp\bin\app.exe",
    RelativePath = @".\bin\app.exe"
});

// Shortcut with LinkInfo (local volume)
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Windows\notepad.exe",
    LinkInfo = new LinkInfo
    {
        Local = new LocalPathInfo
        {
            BasePath = @"C:\Windows\notepad.exe",
            DriveType = DriveTypes.Fixed,
            DriveSerialNumber = 0x1234ABCD,
            VolumeLabel = "Windows"
        }
    }
});

// Shortcut with LinkInfo (network share)
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"\\server\share\docs\report.docx",
    LinkInfo = new LinkInfo
    {
        Network = new NetworkPathInfo
        {
            ShareName = @"\\server\share",
            CommonPathSuffix = @"docs\report.docx"
        }
    }
});

// Shortcut with KnownFolder data block
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Windows\notepad.exe",
    KnownFolder = new KnownFolderData
    {
        FolderId = KnownFolderIds.Windows
    }
});

// Shortcut with distributed link tracker
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Windows\notepad.exe",
    Tracker = new TrackerData
    {
        MachineId = "WORKSTATION01",
        VolumeId = Guid.Parse("a1b2c3d4-e5f6-7890-abcd-ef1234567890"),
        ObjectId = Guid.Parse("12345678-9abc-def0-1234-567890abcdef")
    }
});

// Icon with environment variable path
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Windows\notepad.exe",
    IconEnvironmentPath = @"%SystemRoot%\system32\shell32.dll"
});

// Special folder data block
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Windows\notepad.exe",
    SpecialFolder = new SpecialFolderData
    {
        FolderId = CsidlFolderIds.Windows
    }
});

// Console shortcut with display settings
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Windows\System32\cmd.exe",
    Console = new ConsoleData
    {
        ScreenBufferSizeX = 120,
        ScreenBufferSizeY = 9001,
        WindowSizeX = 120,
        WindowSizeY = 30,
        FaceName = "Consolas",
        QuickEdit = true
    },
    ConsoleCodePage = 65001   // UTF-8
});

// MSI advertised shortcut (Darwin data block)
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Windows\notepad.exe",
    DarwinData = "[ProductCode]>Feature>Component"
});

// App compatibility shim
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\OldApp\setup.exe",
    ShimLayerName = ShimLayerNames.WinXPSP3
});

// Explicit file attributes
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Windows\notepad.exe",
    FileAttributes = FileAttributes.Hidden | FileAttributes.System | FileAttributes.Archive
});

// Network share with mapped drive and provider
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"\\server\share\file.txt",
    LinkInfo = new LinkInfo
    {
        Network = new NetworkPathInfo
        {
            ShareName = @"\\server\share",
            CommonPathSuffix = "file.txt",
            DeviceName = "Z:",
            NetworkProviderType = NetworkProviderTypes.Lanman
        }
    }
});

// Typed property store (AppUserModelId for taskbar grouping)
var builder = new PropertyStoreBuilder
{
    AppUserModelId = "MyCompany.MyApp",
    PreventPinning = true
};
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\MyApp\app.exe",
    PropertyStoreData = builder.Build()
});

// PropertyStore with System.Link and named properties
var builder = new PropertyStoreBuilder
{
    AppUserModelId = "MyCompany.MyApp",
    TargetParsingPath = @"C:\MyApp\app.exe",
    ItemTypeText = "Application"
};
builder.AddNamedStringProperty("CustomTag", "MyValue");
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\MyApp\app.exe",
    PropertyStoreData = builder.Build()
});

// Unicode LinkInfo for non-ASCII paths (auto-detects when needed)
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Users\ユーザー\Documents\レポート.docx",
    LinkInfo = new LinkInfo
    {
        Local = new LocalPathInfo
        {
            BasePath = @"C:\Users\ユーザー\Documents\レポート.docx",
            VolumeLabel = "データ"
        }
    }
});

// Force Unicode LinkInfo explicitly
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\test.exe",
    UseUnicodeLinkInfo = true,
    LinkInfo = new LinkInfo
    {
        Local = new LocalPathInfo { BasePath = @"C:\test.exe" }
    }
});

// WinX Power User Menu shortcut (Win+X menu)
byte[] propStore = WinXHasher.BuildPropertyStore(@"C:\Windows\System32\cmd.exe");
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Windows\System32\cmd.exe",
    PropertyStoreData = propStore
});

// Parse property store data from an existing shortcut
ShortcutOptions opts = Shortcut.Open(File.ReadAllBytes("shortcut.lnk"));
if (opts.PropertyStoreData != null)
{
    var entries = PropertyStoreReader.Parse(opts.PropertyStoreData);
    foreach (var entry in entries)
        Console.WriteLine($"{entry.FormatId} PID={entry.PropertyId} Name={entry.Name} Value={entry.Value}");
}

// Decode a Darwin (MSI) descriptor
var darwin = DarwinDescriptor.TryDecode(opts.DarwinData);
if (darwin != null)
{
    Console.WriteLine($"Product: {darwin.ProductCode}");
    Console.WriteLine($"Feature: {darwin.FeatureId}");
    Console.WriteLine($"Component: {darwin.ComponentCode}");
}

// Forensic extraction from TrackerData
if (opts.Tracker != null)
{
    Console.WriteLine($"MAC: {opts.Tracker.ExtractMacAddressString()}");
    Console.WriteLine($"Timestamp: {opts.Tracker.ExtractTimestamp()}");
    Console.WriteLine($"Birth MAC: {opts.Tracker.ExtractBirthMacAddressString()}");
}

// Preserve unknown extra data blocks during round-trip
var parsed = Shortcut.Open(File.ReadAllBytes("shortcut.lnk"));
// Any unrecognized extra data blocks are preserved in UnknownExtraDataBlocks
byte[] roundTripped = Shortcut.Create(parsed);

// Strip privacy-sensitive metadata (machine name, MAC address, unknown blocks, etc.)
byte[] original = File.ReadAllBytes("shortcut.lnk");
byte[] sanitized = ShortcutSanitizer.SanitizeBytes(original);
File.WriteAllBytes("clean.lnk", sanitized);

// Allow shortcut to link to another .lnk file
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Users\Desktop\other.lnk",
    AllowLinkToLink = true
});

// All features combined
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Windows\notepad.exe",
    Arguments = "test.txt",
    Description = "Full-featured shortcut",
    WorkingDirectory = @"C:\Windows",
    IconLocation = @"C:\Windows\notepad.exe",
    WindowStyle = ShortcutWindowStyle.Maximized,
    RunAsAdmin = true,
    HotkeyKey = VirtualKeys.T,
    HotkeyModifiers = HotkeyModifiers.Control | HotkeyModifiers.Alt,
    UseUnicode = true,
    CreationTime = DateTime.UtcNow,
    FileSize = 193536,
    RelativePath = @".\notepad.exe",
    LinkInfo = new LinkInfo
    {
        Local = new LocalPathInfo
        {
            BasePath = @"C:\Windows\notepad.exe",
            VolumeLabel = "C"
        }
    },
    KnownFolder = new KnownFolderData { FolderId = KnownFolderIds.Windows },
    Tracker = new TrackerData
    {
        MachineId = "MYPC",
        VolumeId = Guid.NewGuid(),
        ObjectId = Guid.NewGuid()
    }
});

Opening Shortcuts

Parse an existing .lnk file to inspect or reuse its properties:

using ShortcutLib;

// Read an existing shortcut
byte[] data = File.ReadAllBytes("Notepad.lnk");
ShortcutOptions options = Shortcut.Open(data);

Console.WriteLine(options.Target);           // C:\Windows\notepad.exe
Console.WriteLine(options.Description);      // My Notepad Shortcut
Console.WriteLine(options.WindowStyle);      // Normal
Console.WriteLine(options.RunAsAdmin);       // False

Editing Shortcuts

Modify specific properties of an existing shortcut without rebuilding from scratch:

using ShortcutLib;

byte[] original = File.ReadAllBytes("Notepad.lnk");

// Change target and add arguments
byte[] modified = Shortcut.Edit(original, options =>
{
    options.Target = @"C:\Windows\System32\cmd.exe";
    options.Arguments = "/k echo Hello";
    options.RunAsAdmin = true;
});

File.WriteAllBytes("Admin-CMD.lnk", modified);

// Change window style
byte[] maximized = Shortcut.Edit(original, options =>
{
    options.WindowStyle = ShortcutWindowStyle.Maximized;
});

// Add a hotkey
byte[] withHotkey = Shortcut.Edit(original, options =>
{
    options.HotkeyKey = VirtualKeys.T;
    options.HotkeyModifiers = HotkeyModifiers.Control | HotkeyModifiers.Alt;
});

API

Shortcut.Open

public static ShortcutOptions Shortcut.Open(byte[] data)

Parses a .lnk file's binary content and returns a ShortcutOptions object with all recognized properties populated. Throws ArgumentException if data is too short and FormatException if the header is invalid.

Shortcut.Edit

public static byte[] Shortcut.Edit(byte[] data, Action<ShortcutOptions> modify)

Opens an existing .lnk file, applies the modification callback, and returns the re-serialized result as a new byte array. Unmodified properties are preserved.

Shortcut.Create

public static byte[] Shortcut.Create(ShortcutOptions options)

ShortcutOptions

ShortcutWindowStyle

HotkeyModifiers

Combinable flags for hotkey modifier keys:

Use VirtualKeys constants for HotkeyKey: VirtualKeys.A–VirtualKeys.Z, VirtualKeys.D0–VirtualKeys.D9, VirtualKeys.F1–VirtualKeys.F24, VirtualKeys.NumLock, VirtualKeys.ScrollLock.

LinkInfo

Describes the target's location per [MS-SHLLINK] 2.3. Provide Local, Network, or both.

LocalPathInfo:

NetworkPathInfo:

KnownFolderData

KnownFolderIds

Predefined GUIDs for common known folders (55 constants):

User folders: Desktop, Documents, Downloads, Music, Pictures, Videos, Profile, SavedGames, Contacts, Searches, Favorites, Links, Templates

System: ProgramFiles, ProgramFilesX86, ProgramFilesCommon, ProgramFilesCommonX86, System, SystemX86, Windows, Fonts

Application data: AppData, LocalAppData, LocalAppDataLow, ProgramData

Start menu: StartMenu, Programs, Startup, AdminTools

Common (all-users): CommonStartMenu, CommonPrograms, CommonStartup, CommonDesktopDir, CommonTemplates, CommonAdminTools

Public: UserProfiles, Public, PublicDesktop, PublicDocuments, PublicDownloads, PublicMusic, PublicPictures, PublicVideos

Shell locations: RecycleBin, QuickLaunch, SendTo, Recent, PrintHood, NetHood, Cookies, History, InternetCache, UserProgramFiles

TrackerData

Distributed link tracking service data per [MS-SHLLINK] 2.5.10.

SpecialFolderData

FileAttributes

[Flags] enum for explicit target file attributes:

ReadOnly, Hidden, System, Directory, Archive, Normal, Temporary, SparseFile, ReparsePoint, Compressed, Offline, NotContentIndexed, Encrypted

When ShortcutOptions.FileAttributes is null, attributes are auto-detected from the target path.

ConsoleData

Console display settings for ConsoleDataBlock (signature 0xA0000002, 204 bytes).

NetworkProviderTypes

Well-known WNNC_NET_* constants (45 values): Lanman, Netware, SunPcNfs, Vines, Avid, Docuspace, Mangosoft, Sernet, Riverfront1, Riverfront2, Decorb, Protstor, FjRedir, Distinct, Twins, Rdr2Sample, Csc, ThreeIn1, ExtendNet, Stac, Foxbat, Yahoo, Exifs, Dav, Knoware, ObjectDire, Masfax, HobNfs, Shiva, Ibmal, Lock, TerminalServices, Srt, Quincy, OpenAfs, Avid1, Dfs, Kwnp, Zenworks, DriveOnWeb, VMware, Rsfx, Mfiles, MsNfs, Google

PropertyStoreBuilder

Builds typed MS-PROPSTORE data for ShortcutOptions.PropertyStoreData:

var builder = new PropertyStoreBuilder
{
    AppUserModelId = "MyCompany.MyApp",
    PreventPinning = true,
    ToastActivatorCLSID = Guid.Parse("..."),
    RelaunchCommand = "myapp.exe --relaunch"
};
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\MyApp\app.exe",
    PropertyStoreData = builder.Build()
});

AppUserModel properties (Format ID: 9F4C2855-9CDB-4D7B-82BF-440971C8D266):

System.Link properties (Format ID: B9B4B3FC-2B51-4A42-B5D8-324146AFCF25):

Other storage properties:

Named properties (arbitrary string-keyed name/value pairs):

var builder = new PropertyStoreBuilder();
builder.AddNamedStringProperty("CustomKey", "CustomValue")
       .AddNamedUInt32Property("Count", 42)
       .AddNamedBoolProperty("Enabled", true)
       .AddNamedInt32Property("Status", -1)
       .AddNamedFileTimeProperty("Timestamp", DateTime.UtcNow);

ShortcutSanitizer

Strips privacy-sensitive metadata from shortcut files. LNK files may contain forensic artifacts: machine name and MAC address (TrackerData), file owner and computer name (PropertyStoreData), and unstructured data after the terminal block (OverlayData).

// Sanitize in-place
ShortcutSanitizer.Sanitize(options);

// Or sanitize a raw byte array
byte[] clean = ShortcutSanitizer.SanitizeBytes(File.ReadAllBytes("shortcut.lnk"));

PropertyStoreReader

Parses serialized MS-PROPSTORE binary data back into typed entries:

var entries = PropertyStoreReader.Parse(options.PropertyStoreData);
foreach (var entry in entries)
{
    Console.WriteLine($"FormatId={entry.FormatId} PID={entry.PropertyId} Name={entry.Name}");
    Console.WriteLine($"  VtType={entry.VtType} Value={entry.Value}");
}

Returns a List<PropertyStoreEntry> with each entry containing:

Supported VT types: VT_LPWSTR (31), VT_BOOL (11), VT_UI4 (19), VT_I4 (3), VT_CLSID (72), VT_FILETIME (64), VT_I2 (2), VT_UI2 (18), VT_I8 (20), VT_UI8 (21), VT_BLOB (65), VT_LPSTR (30). Unknown types return the raw bytes as byte[].

WinXHasher

Computes the hash required for Windows 10+ Power User Menu (Win+X) shortcuts:

// Compute hash only
uint hash = WinXHasher.ComputeHash(@"C:\Windows\System32\cmd.exe");

// With arguments
uint hash = WinXHasher.ComputeHash(@"C:\Windows\System32\cmd.exe", "/k echo test");

// Build a complete property store with the hash embedded
byte[] propStore = WinXHasher.BuildPropertyStore(@"C:\Windows\System32\cmd.exe");
byte[] lnk = Shortcut.Create(new ShortcutOptions
{
    Target = @"C:\Windows\System32\cmd.exe",
    PropertyStoreData = propStore
});

// Or use PropertyStoreBuilder for more control
var builder = new PropertyStoreBuilder
{
    WinXHash = WinXHasher.ComputeHash(@"C:\test.exe"),
    AppUserModelId = "MyApp"
};

DarwinDescriptor

Decodes MSI (Windows Installer) Darwin descriptor strings from DarwinDataBlock:

var darwin = DarwinDescriptor.TryDecode(options.DarwinData);
if (darwin != null)
{
    Console.WriteLine($"Product: {darwin.ProductCode}");
    Console.WriteLine($"Feature: {darwin.FeatureId}");
    Console.WriteLine($"Component: {darwin.ComponentCode}");
}

// Encode a GUID to MSI compressed format
string packed = DarwinDescriptor.EncodeCompressedGuid(someGuid);

TrackerData Forensic Methods

Version 1 UUIDs in TrackerData contain embedded MAC addresses and timestamps. These methods extract that forensic information:

var tracker = options.Tracker;
if (tracker != null && tracker.IsObjectIdVersion1())
{
    byte[] mac = tracker.ExtractMacAddress();       // [0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF]
    string macStr = tracker.ExtractMacAddressString(); // "AA:BB:CC:DD:EE:FF"
    DateTime? ts = tracker.ExtractTimestamp();       // UTC timestamp from UUID

    // Birth IDs (original machine that created the file)
    string birthMac = tracker.ExtractBirthMacAddressString();
    DateTime? birthTs = tracker.ExtractBirthTimestamp();
}

RawExtraDataBlock

Unrecognized extra data blocks are preserved during round-trips:

DriveTypes

Drive type constants for LocalPathInfo.DriveType:

Unknown (0), NoRootDir (1), Removable (2), Fixed (3), Remote (4), CDRom (5), RamDisk (6)

CsidlFolderIds

CSIDL folder ID constants for SpecialFolderData.FolderId (45 values):

Desktop, Internet, Programs, Controls, Printers, Personal, Favorites, Startup, Recent, SendTo, RecycleBin, StartMenu, MyMusic, MyVideo, DesktopDirectory, Drives, Network, NetHood, Fonts, Templates, CommonStartMenu, CommonPrograms, CommonStartup, CommonDesktopDirectory, AppData, PrintHood, LocalAppData, CommonAppData, Windows, System, ProgramFiles, MyPictures, Profile, SystemX86, ProgramFilesX86, CommonFiles, CommonFilesX86, CommonTemplates, CommonDocuments, AdminTools, CommonAdminTools, Cookies, History, InternetCache

VirtualKeys

Virtual key code constants for ShortcutOptions.HotkeyKey:

Letters: A–Z (0x41–0x5A) | Digits: D0–D9 (0x30–0x39) | Function keys: F1–F24 (0x70–0x87) | Toggle: NumLock, ScrollLock

ConsoleFillAttributes

Console color flag constants for ConsoleData.FillAttributes and PopupFillAttributes:

ForegroundBlue, ForegroundGreen, ForegroundRed, ForegroundIntensity, BackgroundBlue, BackgroundGreen, BackgroundRed, BackgroundIntensity

ConsoleFontFamilies

Font family and pitch constants for ConsoleData.FontFamily:

Families: DontCare, Roman, Swiss, Modern, Script, Decorative | Pitch: FixedPitch, Vector, TrueType, Device

ShimLayerNames

Common compatibility shim layer names for ShortcutOptions.ShimLayerName:

OS compatibility: Win95, Win98, WinNT4SP5, Win2000, Win2000SP3, WinXPSP1, WinXPSP2, WinXPSP3, WinVistaSP1, WinVistaSP2, Win7RTM, Win8RTM, Win81RTM, Win10RTM

Display: Color256, Resolution640x480, ReducedColorMode, DisableDWM, GdiScalingOff, GdiDpiScaling, HighDpiAware, DpiUnaware, PerProcessSystemDpiForceOn, PerMonitorV2

Behavior: DisableNXShowUI, DisableThemes, RunAsAdmin, ForceDirectDrawEmulation, ElevateCreateProcess, DisableUserCallbackException

Argument Padding

When PadArguments is true, the arguments string is placed at the end of a 31 KB buffer filled with whitespace and control characters (CR, Tab, LF, file/group/record/unit separators, Space). This pushes the actual arguments beyond what the Windows shortcut properties dialog displays, effectively hiding them from casual inspection.

File vs. Directory Detection

The library classifies the target as a file or directory based on its extension length:

• File (FILE_ATTRIBUTE_ARCHIVE): Extension is 1–3 characters (e.g. .exe, .txt, .a)
• Directory (FILE_ATTRIBUTE_DIRECTORY): No extension, or extension longer than 3 characters

Path Handling

• Local paths are split on the first \. The root portion gets a trailing \ (e.g. C:\), the remainder becomes the leaf item.
• Network paths (starting with \\) are split on the last \. The server+share portion is the root, the final component is the leaf.
• Printer links treat the entire target as the root (no leaf item).

Building

dotnet build

Testing

dotnet test

License

MIT