This could be guaranteed by installing a "fideicommissum". Roman law had a well-developed concept of the trust ("fideicommissum") created by wills. They are derived from "fideicommissum", a legal institution in Roman law. An analogy exists between uses and a usufructus (usufruct) or the bequest of a fideicommissum. They restricted liberation of slaves, but could be partly evaded by the "fideicommissum". The practical informality and flexibility of "fideicommissum" is described in "Institutes", 2.23.2. The surrounding property is one of the few remaining in Sweden still held as "fideicommissum". This of course did not apply for the "fideicommissum" and with such could be evaded. Most important, the "fideicommissum" enabled transferring property by will to those excluded from inheriting.