NIP-40: Event expiration
An expiration tag limits how long a relay should serve an event. The exact expiry second is already expired.
Implementation
The Coax relay checks expiration during admission and queries. Its store retains expired replacement heads so older versions do not return.
Example
The shared relay expiration predicate runs at explicit fixture times. No event is published or deleted.
What remains
Expiration is not a deletion guarantee, and a relay cannot erase copies held elsewhere.