diff --git a/09.md b/09.md
index e174865..a0c1ec6 100644
--- a/09.md
+++ b/09.md
@@ -53,7 +53,7 @@ For example:
 
 The above event requests the deletation of all text notes and reactions from a user.
 
-A kind 5 MUST NOT contain a `f` tag beside other tags, or multiple `f` tags in one event.
+A kind 5 MUST NOT contain a `f` tag beside other tags, or multiple `f` tags in one event. The `"authors"` field of filter should be implicit.
 
 ### Usages
 
@@ -76,3 +76,7 @@ Relays MAY validate that a deletion request event only references events that ha
 ## Deletion Request of a Deletion Request
 
 Publishing a deletion request event against a deletion request has no effect.  Clients and relays are not obliged to support "unrequest deletion" functionality.
+
+## Protection for a Deletion Request
+
+if the deletion request is intended to be applied in a set of limited relays, clients can send them as protected events and expect other relays to don't execute them in sync or broadcasting.