1. "to A, but if X event happens, grantor reserves the right to RENTER and RETAKE"
2. INFINITE (potentially), so long as
- NO BREACH of condition, and
- if breach occurs, until GRANTOR TERMINATES (timely) upon breach of condition
3. Devisable, descendable, an alienable subject to condition
4. RE-ENTRY, or power of TERMINATION (held by grantor)