How many security levels are there in the federal prison system according to the bureau of prisons classification?

I believe the answer is: 5

The first level is called minimum security, where they keep non-violent convicts. The second level is low security, where they keep convicts with minimum violents
The third level is medium security where they store violent criminals with less than 30-years prison time
The fourth level is High security where they store violents offenders that mostly become the target of other inmates.
the fifth level is Administrative Security:  where they stored the convicts that categorized as national threat