123vier on Nostr: #[0]

quoting nevent1q…lrhw

NIP-3 specifies how to use OpenTimestamps to timestamp events, proving they existed prior to a point in time: https://github.com/nostr-protocol/nips/blob/master/03.md

But it may also be useful to prove events were created _after_ a point in time. The easiest way to do that would be to add a tag with a recent block hash to every event you create.