The enna (pl. ennuar) is the fundamental social unit of Yivrian society. It may be characterized as a matrilineal, uxorilocal extended family, with elements of a patrilineal system of inheritance mixed in. The enna fulfilled a social and economic role similar to that of the clan or nuclear family, and combining certain attributes of each of them. Yivrian law and custom had very little to say about the rights of individuals; rather, almost all legal and social thought was concerned with relationships between enna.
Fundamental structure of the enna
An enna was a family unit consisting of the following classes of people:
- All females who shared a common living ancestor.
- All men married to such women.
- All children of such women.
As these rules imply, a woman would spend her entire life within the same enna, except for when the Eldest of the enna died and the enna would be reformed beneath a new ancestor. A woman's membership in an enna did not change when she married or had children. A man, on the other hand, would be born into his mother's enna, but would also join his wife's enna when he married. Married men, therefore, would have membership in two ennuar: their mother's, which they were born into, and their wife's, which they joined upon marriage. This dual-membership in different ennuar only applied to men; women did not join their husband's enna, nor did their children belong to the husband's enna. In this sense the enna was matrilineal. The enna was also uxorilocal, meaning that a husband lived with his wife's enna after marriage, leaving the enna of his mother and father.
The following chart shows an idealized family tree indicating the membership in an enna. Women are colored red and men are colored blue. The members of the enna are within green boxes. Men who belonged to the enna but lived with their wives in a different enna are underlined in black.