(a) estates pur autre vie, whether there is or is not a special occupant and whether they are corporeal or incorporeal hereditaments,

(b) contingent, executory or other future interest in real or personal property, whether the testator is or is not ascertained as the person or one of the persons in whom those interests may respectively become vested, and whether he is entitled to them under the instrument by which they were respectively created or under a disposition of them by deed or will, and

(c) rights of entry.