diff --git a/100.md b/100.md
index adb5115..3a0a0e0 100644
--- a/100.md
+++ b/100.md
@@ -61,6 +61,17 @@ Optionally, clients CAN prevent the sending of events signed by a locked user, a
 
 For the key thief, this is easily avoidable by using another client or developing a custom one, which is why it is defined as an optional feature in this NIP. However, any difficulty in the illicit use of a key will be welcomed.
 
+### NIP-42 Usage
+
+Relays that support _Authentication of clients to relays_ ([NIP-42](./42.md)) must take into account that a user has been blocked when a client attempts to authenticate via the `AUTH` message. When a client attempts to authenticate by sending a `kind: 22242` event for a user that has been blocked, the relays will respond with an `OK` message indicating in the 3rd parameter the value `false`, and the 4th parameter will use the prefix `blocked`. For example:
+
+- `["OK", "b1a649ebe8...", false, "blocked: you have been blocked"]`
+
+Additionally, relays must close existing subscriptions for that user to prevent the client from receiving events they are no longer authorized to receive. This will be done through the `CLOSE` message, using the prefix `blocked` in the 3rd parameter.
+
+- `["CLOSED", "sub1", "blocked: you have been blocked"]`
+
+
 ### Considerations
 
 1. Once a user is locked, **this action is irreversible**, so the keys would remain locked in the Relays and clients that implement this NIP forever.