nips/1078.md

# NIP-1078

## Arbitrary custom app data
`draft` `optional` `author:BlowaterNostr`

## Nostr event

This NIP specifies the use of event kind `1078` which is almost identical to [30078](https://github.com/nostr-protocol/nips/blob/master/78.md) except that it's not a replacible event.

## Some use cases
The reason to not having a 30078 is that some clients want to implement local state changes as [CRDTs](https://crdt.tech/), meaning support cumulative and associative mutations

Cumulative and associative means the order of applying operations doesn't change the final result as long as the same set of operations are applied.

Using regular events can reserve the event/operation history thus the client can recompute the final state easily. [Figma uses CRDT to implement their vector design system.](https://www.figma.com/blog/how-figmas-multiplayer-technology-works/)

## Implementations
For example, in [Blowater](https://blowater.deno.dev), Pin/Unpin Contacts is implemented as regular events to achieve better consistency.

Event set [`Pin Npub X`, `Unpin NpubX`, `Pin Npub Y`] will result in a pin list of `[Y]` no matter how the order is shifted.

Many other operations are best implemented as CRDTs as well.