Token_privileges ?

Please tell me the meaning of TOKEN_PRIVILEGES & LUID structures or the links where I can find their details. I have come across these terms in many places in this forum. I know these are used with Win NT systems. But don't know what they mean. I have also used SECURITY_ATTRIBUTES which I believe sets the rights of the person in the WinNt system. Please help.

I am enclosing the structure details below :

Private Type LUID
UsedPart As Long
IgnoredForNowHigh32BitPart As Long
End Type

Private Type LUID_AND_ATTRIBUTES
TheLuid As LUID
Attributes As Long
End Type
Private Type TOKEN_PRIVILEGES
PrivilegeCount As Long
TheLuid As LUID
Attributes As Long
End Type
Private Type SECURITY_ATTRIBUTES
nLength As Long
lpSecurityDescriptor As Long
bInheritHandle As Long
End Type