added a third option to approve replaceable events.

172.md

@@ -80,7 +80,7 @@ The post-approval event MUST include `a` tags of the communities the moderator i
 
 It's recommended that multiple moderators approve posts to avoid deleting them from the community when a moderator is removed from the owner's list. In case the full list of moderators must be rotated, the new moderator set must sign new approvals for posts in the past or the community will restart. The owner can also periodically copy and re-sign of each moderator's approval events to make sure posts don't dissapear with moderators. 
 
-Replaceable events can be submitted for approval in two ways: (i) by their `e` tag if moderators want to approve each individual change to the repleceable event or (ii) by the `a` tag if the moderator trusts the original post author to not modify the event beyond community rules. 
+Post Approvals of replaceable events can be created in three ways: (i) by tagging the replaceable event as an `e` tag if moderators want to approve each individual change to the repleceable event; (ii) by tagging the replaceable event as an `a` tag if the moderator authorizes the replaceable event author to make changes without additional approvals and (iii) by tagging the replaceable event with both its `e` and `a` tag which empowers clients to display the original and updated versions of the event, with appropriate remarks in the UI. Since relays are instructed to delete old versions of a replaceable event, the `.content` of an `e`-approval MUST have the specific version of the event or Clients might not be able to find that version of the content anywhere.
 
 Clients SHOULD evaluate any non-`34550:*` `a` tag as posts to be included in all `34550:*` `a` tags.