Carl's class, required to pick one of three permanent specialties on the sixth floor.
When Carl enters the Specialization booth, the screen informs him that his class, Compensated Anarchist, is required to pick a specialty, that he will have three choices, that the choice is permanent, that a random one will be applied if he does not choose, and that he retains all previous class upgrades.
The three branches offered are Revolutionary, Guerilla, and Agent Provocateur — roughly the fighting, traps, and explosives options Carl and Mordecai had predicted. All three carry an unexpected stat point boost, and none of them add penalties to the other two. Carl ends the chapter as a level 47 Agent Provocateur.
Carl's base class throughout the crawl, now permanently branched.
Also appears in books you've already read — spoiler-safe to their endings: