# 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.