diff --git a/51.md b/51.md
index 55834352..a8a54c35 100644
--- a/51.md
+++ b/51.md
@@ -152,6 +152,25 @@ Some clients have used these lists in the past, but they should work on transiti
 }
 ```
 
+### Link Safety
+
+A kind `10099` replaceable event for storing user domain preferences.
+
+```jsonc
+{
+  "kind": 10099,
+  "content": "",
+  "tags": [
+    ["d", "domain_lists"], // identifier 
+    ["white", "nostr.build"],
+    ["white", "void.cat"],
+    ["black", "malicious-site.net"],
+    ["black", "scam-domain.com"]
+    ["unknown", "ask"]  // Options: "load" | "block" | "ask"
+  ]
+}
+```
+
 ## Encryption process pseudocode
 
 ```scala