In Kilrathi society I understand that there are two main types of Kilrathi, Thrak'hra (the high-born), and Kilrah'hra (the low-born). Are Thrak'hra the only ones that are found in organized clans, or do Kilrah'hra have their own clans? What is a Kilrah'hra's role in Kilrathi society? Are they allowed to join the military, or are they serfs of sort to Thrak'hra lords?