diff --git a/42.md b/42.md
index 07a04864..8c70de49 100644
--- a/42.md
+++ b/42.md
@@ -20,19 +20,19 @@ A relay may want to require clients to authenticate to access restricted resourc
 
 ### New client-relay protocol messages
 
-This NIP defines a new message, `AUTH`, which relays can send when they support authentication and clients can send to relays when they want to authenticate. When sent by relays, the message is of the following form:
+This NIP defines a new message, `AUTH`, which relays CAN send when they support authentication and clients can send to relays when they want to authenticate. When sent by relays the message has the following form:
 
 ```json
 ["AUTH", <challenge-string>]
 ```
 
-And, when sent by clients, of the following form:
+And, when sent by clients, the following form:
 
 ```json
 ["AUTH", <signed-event-json>]
 ```
 
-`AUTH` messages sent by clients should be answered with an `OK` message, like any `EVENT` message.
+`AUTH` messages sent by clients MUST be answered with an `OK` message, like any `EVENT` message.
 
 ### Canonical authentication event