diff --git a/18.md b/18.md
index 27c5915a..41c94424 100644
--- a/18.md
+++ b/18.md
@@ -25,6 +25,14 @@ quote reposted. The `q` tag ensures quote reposts are not pulled and included
 as replies in threads. It also allows you to easily pull and count all of the
 quotes for a post.
 
+`q` tags should follow the same conventions as NIP 10 `e` tags, with the exception
+of the `mark` argument.
+
+`["q", <event-id>, <relay-url>, <pubkey>]`
+
+Quote reposts MUST include the [NIP-21](21.md) `nevent`, `note`, or `naddr` of the
+event in the content.
+
 ## Generic Reposts
 
 Since `kind 6` reposts are reserved for `kind 1` contents, we use `kind 16`