C# Definition:

[Flags]
public 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:

<Flags()> _
Public Enum ACCESS_MASK : Uint32
    DELETE = &H10000
    READ_CONTROL = &H20000
    WRITE_DAC = &H40000
    WRITE_OWNER = &H80000
    SYNCHRONIZE = &H100000

    STANDARD_RIGHTS_REQUIRED = &HF0000

    STANDARD_RIGHTS_READ = &H20000
    STANDARD_RIGHTS_WRITE = &H20000
    STANDARD_RIGHTS_EXECUTE = &H20000

    STANDARD_RIGHTS_ALL = &H1F0000

    SPECIFIC_RIGHTS_ALL = &HFFFF

    ACCESS_SYSTEM_SECURITY = &H1000000

    MAXIMUM_ALLOWED = &H2000000

    GENERIC_READ = &H80000000
    GENERIC_WRITE = &H40000000
    GENERIC_EXECUTE = &H20000000
    GENERIC_ALL = &H10000000

    DESKTOP_READOBJECTS = &H1
    DESKTOP_CREATEWINDOW = &H2
    DESKTOP_CREATEMENU = &H4
    DESKTOP_HOOKCONTROL = &H8
    DESKTOP_JOURNALRECORD = &H10
    DESKTOP_JOURNALPLAYBACK = &H20
    DESKTOP_ENUMERATE = &H40
    DESKTOP_WRITEOBJECTS = &H80
    DESKTOP_SWITCHDESKTOP = &H100

    WINSTA_ENUMDESKTOPS = &H1
    WINSTA_READATTRIBUTES = &H2
    WINSTA_ACCESSCLIPBOARD = &H4
    WINSTA_CREATEDESKTOP = &H8
    WINSTA_WRITEATTRIBUTES = &H10
    WINSTA_ACCESSGLOBALATOMS = &H20
    WINSTA_EXITWINDOWS = &H40
    WINSTA_ENUMERATE = &H100
    WINSTA_READSCREEN = &H200

    WINSTA_ALL_ACCESS = &H37F
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.