One of the central devices for attempting to keep property together and provide for family continuity was the fideicommissum, which was a trust adapted from elements of Roman law. Fideicommissum combined substitution of heirs in agnation, so male lines did not die out, with prohibition of alienation of key family properties extra familiam (making them effectively inalienable). Legal experts had difficulties allowing the Roman fideicommissum, limited to four generations, to endure indefinitely, so they demanded some precise language in testaments of other instruments that established fideicommissa, including clear statement of a testator's intent that property not leave the family, which was at least seen as a laudable goal of legal property management.