Originally Posted by
chollie
Actually, there's no clear definition of any of the versions of MI.
FSDs and individual screeners decide which flavors, if any, of MI will be applied at a particular checkpoint or airport at any particular time.
If you know the rules and they are practiced consistently, then the bad guys will get in. That's why even some FFs show up at Pre unprepared - you never know what to expect.
In my case Pre Check was printed on my boarding pass 24 hours before the flight so I doubt that any of the local screeners had any part in the decision. As I said up thread I don't know the mechanism but I suspect it has to do with when a name is submitted for clearance and some factor is arrived at awarding Pre.