NIP-10

On "e" and "p" tags in Text Events (kind 1).

draft optional author:unclebobmartin

Abstract

This NIP describes how to use "e" and "p" tags in text events, especially those that are replies to other text events. It helps clients thread the replies into a tree rooted at the original event.

Positional "e" tags (DEPRECATED)

This scheme is in common use; but should be considered deprecated.

["e", <event-id>, <relay-url>] as per NIP-01.

Where:

• <event-id> is the id of the event being referenced.
• <relay-url> is the URL of a recommended relay associated with the reference. Many clients treat this field as optional.

The positions of the "e" tags within the event denote specific meanings as follows:

• No "e" tag:
  This event is not a reply to, nor does it refer to, any other event.

• One "e" tag:
  ["e", <id>]: The id of the event to which this event is a reply.

• Two "e" tags: ["e", <root-id>], ["e", <reply-id>]
<root-id> is the id of the event at the root of the reply chain. <reply-id> is the id of the article to which this event is a reply.

• Many "e" tags: ["e", <root-id>] ["e", <mention-id>], ..., ["e", <reply-id>]
  There may be any number of <mention-ids>. These are the ids of events which may, or may not be in the reply chain. They are citings from this event. root-id and reply-id are as above.

This scheme is deprecated because it creates ambiguities that are difficult, or impossible to resolve when an event references another but is not a reply.

Marked "e" tags (PREFERRED)

["e", <event-id>, <relay-url>, <marker>]

Where:

• <event-id> is the id of the event being referenced.
• <relay-url> is the URL of a recommended relay associated with the reference. Clients SHOULD add a valid <relay-URL> field, but may instead leave it as "".
• <marker> is optional and if present is one of "reply", "root", or "mention".

Those marked with "reply" denote the id of the reply event being responded to. Those marked with "root" denote the root id of the reply thread being responded to. For top level replies (those replying directly to the root event), only the "root" marker should be used. Those marked with "mention" denote a quoted or reposted event id.

A direct reply to the root of a thread should have a single marked "e" tag of type "root".

This scheme is preferred because it allows events to mention others without confusing them with <reply-id> or <root-id>.

The "p" tag

Used in a text event contains a list of pubkeys used to record who is involved in a reply thread.

When replying to a text event E the reply event's "p" tags should contain all of E's "p" tags as well as the "pubkey" of the event being replied to.

Example: Given a text event authored by a1 with "p" tags [p1, p2, p3] then the "p" tags of the reply should be [a1, p1, p2, p3] in no particular order.