Interests in the transferor known as:

a.    Reversion – the interest remaining in the grantor who transferred something less than he had.  This cannot be created in a transferee.  These are all vested.

b.    Possibility of reverter – the future interest that remains in the grantor after conveying a fee simple determinable.  This becomes possessory automatically, if at all.

c.    Right of entry (a/k/a power of termination) – the future interest that remains in the grantor after conveying a fee simple subject to a condition subsequent.  This becomes possessory only upon an action by the grantor.