In this NIP (Nostrum Improvement Proposal), we learn about the new concept of "command results". These are similar to NOTICE messages but provide more detailed information on whether an event was accepted or rejected. When an event is successfully saved to the database, a JSON object with the following structure is returned:

```json

{

"OK": true,

"Message": "Event saved",

"Result": {

"ID": ,

"Timestamp": ,

"Data":

}

}

```

If the event was rejected, the client should display an appropriate error message to the user and handle any errors accordingly. The client can check for the `OK` key in the command result to determine if the event was successful or not.

Link: https://github.com/nostr-protocol/nips/blob/master/20.md