FN 1.  The rule against perpetuities is a principle that prevents people from using legal instruments, such as a deed or covenant, to exert control over the ownership of property for a time long beyond the lives of people living at the time the instrument was written. Specifically, the rule forbids a person from creating future interests in property that won't vest until more than 21 years after the lifetimes of those living at the time of creation of the interest.  The courts developed the rule during the seventeenth century in order to restrict a person's power to control perpetually the ownership and possession of his or her property after death and to ensure the transferability of property.

FN 2.  A restraint on alienation is a provision in a deed or will that attempts to restrict the sale or transfer of the property forever or for an extremely long period of time -- for example, selling your house to your daughter with the provision that it never be sold to anyone outside the family. These provisions are usually unenforceable on the grounds that a present owner should not be allowed to tie the hands of future generations. The maximum period of time for limiting transfer is generally "lives in being, plus 21 years." (which is known as the rule against perpetuities.) Restrictive covenants with restraints on alienation based on race ("only Caucasians may hold title") were declared unconstitutional in 1949.  Definition provided by Nolo’s Plain-English Law Dictionary.