Software engineers who attend Microsoft's annual Windows Hardware Engineering Conference later this month could get their first taste of a new Windows user permissions model that could change the way thousands of programs are developed and run. But as the company prepares for the final Longhorn development push, questions remain about its plans for a new user privileges model called Least-Privilege User Account, or LUA.

Microsoft claims that LUA will make life tougher for hackers and virus writers by limiting access to administrator permissions on Windows systems. But the company has been mum in recent months about its plans for implementing LUA in Longhorn, and it is considering incentives to encourage adoption of LUA (pronounced "Loo-ah") by skeptical ISVs (independent software vendors), including a new logo program for LUA compliance, according to interviews with ISVs and industry experts. Least permissions is a principle of computer security that recommends giving software applications and their users no more privileges on an operating system than are absolutely necessary.