add checkpoint event

1 files changed, 13 insertions, 0 deletions

diff --git a/37.md b/37.md
index 1ade59d..9ef728b 100644
--- a/37.md
+++ b/37.md
@@ -30,6 +30,19 @@ A blanked `.content` means this draft has been deleted by a client but relays st
 
 Tags `e` and `a` identify one or more anchor events, such as parent events on replies.   
 
+## Checkpoints
+`kind:1234` defines checkpoints that belong to a parent `kind:31234` event. These can serve to provide a revision history of a parent event.
+
+```js
+{
+  "kind": 1234,
+  "tags": [
+    ["a", "31234:<pubkey>:<identifier>"]
+  ],
+  "content": nip44Encrypt(JSON.stringify(draft_event)),
+}
+```
+
 ## Relay List for Private Content
 
 Kind `10013` indicates the user's preferred relays to store private events like Drafts. The event MUST include a list of `relay` URLs in private tags. Private tags are JSON Stringified, NIP-44-encrypted to the signer's keys and placed inside the .content of the event.