# On `e` and `p` tags in Text Events (kind 1).
### A recommendation for clients.

The following seems to be the conventions that are used by `Branle`, `Damus`, and `more-speech` for referencing
events and authors when building a reply.  These conventions help clients build event threads, and alert authors of
replies.

## Definitions:  
 * A reply chain is the list of events from the root event to a specific reply.  
 * A reply thread is the tree of events consisting of all replies beginning at the root.
 * An event id is a 32 byte number in lower-case hexidecimal.

## The `e` tag
Used in a text event contains a single event id.  ["e", "`hex-number`"]  

 * 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.

## 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 with `p` tags P, the replying event's `p` tags should contain P as well as the pubkey of the 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.