One peculiar thing about the City (in the first two parts of the novel, at least) is that everyone must switch their jobs every once in a while, the job being chosen by a machine based in the person's previous record. The punishment for refusing to change jobs or evading them is being sent to labout on the marshes (as explained by Wan who's had experience with this). As an aside, the mayor seemed to remain the mayor (seemed to me) while other characters changed jobs.
A few questions here: what purpose does this system serve? Is it a part of the Experiment, or something made up by the government? How is it related to the real situation in USSR as it was during Strugatskys' time?