Bitcoin Time-Locks Two locking dimensions: absolute (lock until time/block T) and relative (lock for N blocks/seconds after parent confirms). Absolute time-lock — field + CLTV opcode (4 bytes, in tx): - → tx is valid immediately. - → tx valid only at/after block height N. - → tx valid only at/after unix timestamp. For to be enforced, at least one input must have . CLTV (BIP65) aborts the script if . Doesn't pop the value, so follows. Use case: scheduled payment that becomes valid after a date. MTP rule (BIP113) When comparing time-based ( ) lock against block timestamps, use median time past…