Dynastic stewardship of a single house.
Where the other groups measure invention or capital, this one measures duration. Its members did not create a category; they kept one house at a level, across generations, until continuity itself became the product.
The time spans here are unlike anything else in the Library. The Zengoro Hōshi line runs from 718. The Sacher entries cover a marriage, a widowhood and a reinvention of Viennese hospitality. The Seiler dynasty made Zermatt reachable and then habitable. The Sersale family has held one Positano house for three generations. Andrea Kracht and Innegrit Volkhardt run houses their families have run for a century.
The group includes owner-general-managers because in a single-house dynasty the two roles are frequently the same person, standing in the lobby of the building they own.
What the group does not settle: continuity is not the same as quality, and a family that holds a house for a century can also hold it still. Several entries record the generation that had to break with its inheritance to save it.