C# Definition:

[Flags]
enum ACCESS_MASK : uint
{
     DELETE = 0x00010000,
     READ_CONTROL = 0x00020000,
     WRITE_DAC = 0x00040000,
     WRITE_OWNER = 0x00080000,
     SYNCHRONIZE = 0x00100000,

     STANDARD_RIGHTS_REQUIRED = 0x000f0000,

     STANDARD_RIGHTS_READ = 0x00020000,
     STANDARD_RIGHTS_WRITE = 0x00020000,
     STANDARD_RIGHTS_EXECUTE = 0x00020000,

     STANDARD_RIGHTS_ALL = 0x001f0000,

     SPECIFIC_RIGHTS_ALL = 0x0000ffff,

     ACCESS_SYSTEM_SECURITY = 0x01000000,

     MAXIMUM_ALLOWED = 0x02000000,

     GENERIC_READ = 0x80000000,
     GENERIC_WRITE = 0x40000000,
     GENERIC_EXECUTE = 0x20000000,
     GENERIC_ALL = 0x10000000,

     DESKTOP_READOBJECTS = 0x00000001,
     DESKTOP_CREATEWINDOW = 0x00000002,
     DESKTOP_CREATEMENU = 0x00000004,
     DESKTOP_HOOKCONTROL = 0x00000008,
     DESKTOP_JOURNALRECORD = 0x00000010,
     DESKTOP_JOURNALPLAYBACK = 0x00000020,
     DESKTOP_ENUMERATE = 0x00000040,
     DESKTOP_WRITEOBJECTS = 0x00000080,
     DESKTOP_SWITCHDESKTOP = 0x00000100,

     WINSTA_ENUMDESKTOPS = 0x00000001,
     WINSTA_READATTRIBUTES = 0x00000002,
     WINSTA_ACCESSCLIPBOARD = 0x00000004,
     WINSTA_CREATEDESKTOP = 0x00000008,
     WINSTA_WRITEATTRIBUTES = 0x00000010,
     WINSTA_ACCESSGLOBALATOMS = 0x00000020,
     WINSTA_EXITWINDOWS = 0x00000040,
     WINSTA_ENUMERATE = 0x00000100,
     WINSTA_READSCREEN = 0x00000200,

     WINSTA_ALL_ACCESS = 0x0000037f
}

VB Definition:

Enum ACCESS_MASK
   TODO
End Enum

Notes:

This is NOT a complete enum. Access masks have 16 bits of standard rights, and 16 bits of specific rights, that are different depending on the type of object they are applied to. Included in this enum are rights for the Desktop object and Window Station objects.