Privileged
The installer sets this variable to a nonzero value if the installer runs under an account with elevated privileges; it is set to 0 if the account does not have elevated privileges. This only applies to Windows NT-based systems (Windows NT4, 2000, XP, 2003, Vista, 2008, and later); on Windows 9x-based systems (Windows 95, 98, and Me), this variable is always set to a nonzero value because all users have unrestricted access on those systems.
Usage
You can refer to this variable as <Privileged>. In conditional expressions you can omit the brackets and simply use Privileged as a test for elevated privileges.