23. Period where no lives are chosen.

The exact period of 21 years is the full extent of the perpetuity period in all cases where no life is indicated for the purpose, or where every life indicated has predeceased the testator. Accordingly, limitations vesting in persons possibly unborn at the end of a specific number of years, more than 21 years from the date from which the instrument creating them operates, are invalid1. In certain cases where terms of years exceeding 21 years were settled in trusts for persons in succession whose interests under the trusts were valid with respect to the rule, provisions for recouping