C# Definition:

struct GUID {
   public TODO;
}

VB Definition:

    <StructLayout(LayoutKind.Sequential)> _
    Private Structure GUID
    Dim a As Integer
    Dim b As Short
    Dim c As Short
    <MarshalAs(UnmanagedType.ByValArray, SizeConst:=7)> _
    Dim d() As Byte
    End Structure

User-Defined Field Types:

None.

Notes:

You should use System.Guid instead.