What are the motifs in Gulag: A History by Anne Applebaum?

The camps were also characterized by a great deal of inconsistency. One of the places that this is demonstrated is in the arrests and sentences of individuals. As Applebaum points out, one individual might be arrested and sentenced to one of the Gulag camps, while another person arrested for the same thing would be sent into exile. Some foreigners were arrested, and others were not. The secret police also seem to have varied how they picked up arrestees. In some of the mass executions, prisoners were chosen at random for death, while in others certain prisoners were specifically targeted.